1983-gwynne.pdf: “Beetles On The Bottle: Male Buprestids Mistake Stubbies For Females (Coleoptera)”, (1983-02-01; ):
Male Julodimorpha bakewelli White were observed attempting to copulate with beer bottles. Colour and reflection of tubercles on the bottle glass are suggested as causes for attraction and release of sexual behaviour.
1992-rogers.pdf: “How a Publicity Blitz Created The Myth of Subliminal Advertising”, (1992-12-01; ):
[‘Subliminal advertising’ was the Cambridge Analytica of the 1950s.] In September 1957, I began what to me was a serious study of contemporary applied psychology at Hofstra College in Hempstead, Long Island. At exactly the same time, in nearby New York City, an unemployed market researcher named James M. Vicary made a startling announcement based on research in high-speed photography later popularized by Eastman Kodak Company.
His persuasive sales pitch was that consumers would comprehend information projected at 1/ 60,000th of a second, although they could not literally “see” the flash. And he sent a news release to the major media announcing his “discovery”.
…And, as a follow-up, toward the end of 1957 Vicary invited 50 reporters to a film studio in New York where he projected some motion picture footage, and claimed that he had also projected a subliminal message. He then handed out another of his well written and nicely printed news releases claiming that he had actually conducted major research on how an invisible image could cause people to buy something even if they didn’t want to.
The release said that in an unidentified motion picture theater a “scientific test” had been conducted in which 45,699 persons unknowingly had been exposed to 2 advertising messages projected subliminally on alternate nights. One message, the release claimed, had advised the moviegoers to “Eat Popcorn” while the other had read “Drink Coca-Cola.”
…Vicary swore that the invisible advertising had increased sales of popcorn an average of 57.5%, and increased the sales of Coca-Cola an average of 18.1%. No explanation was offered for the difference in size of the percentages, no allowance was made for variations in attendance, and no other details were provided as to how or under what conditions the purported tests had been conducted. Vicary got off the hook for his lack of specificity by stating that the research information formed part of his patent application for the projection device, and therefore must remain secret. He assured the media, however, that what he called “sound statistical controls” had been employed in the theater test. At least as importantly, too, he had observed the proven propagandist’s ploy of using odd numbers, and also including a decimal in a percentage. The figures 57.5 and 18.1% rang with a clear tone of Truth.
…When I learned of Vicary’s claim, I made the short drive to Fort Lee to learn first-hand about his clearly remarkable experiment.
The size of that small-town theater suggested it should have taken considerably longer than 6 weeks to complete a test of nearly 50,000 movie patrons. But even more perplexing was the response of the theater manager to my eager questioning. He declared that no such test had ever been conducted at his theater.
There went my term paper for my psychology class.
Soon after my disappointment, Motion Picture Daily reported that the same theater manager had sworn to one of its reporters that there had been no effect on refreshment stand patronage, whether a test had been conducted or not—a rather curious form of denial, I think.
…Technological Impossibility: Vicary also informed the reporters that subliminal advertising would have its “biggest initial impact” on the television medium.
When I learned of this, I visited the engineering section of RCA…I was assured by their helpful and knowledgeable engineering liaison man that, because of the time required for an electron beam to scan the surface of a television picture tube, and the persistence of the phosphor glow, it was technologically impossible to project a television image faster than the human eye could perceive.
“In a nighttime scene on television, watch the way the image of a car’s headlights lingers; that’s called comet-tailing”, the engineer explained. “See how long it takes before the headlights fade away.” Clearly there was no way that even the slower tachistoscope speeds of 1/3,000th of a second that Vicary had begun talking about in early 1958 could work on contemporary television.
…It has been estimated he collected retainer and consulting fees from America’s largest advertisers totaling some $34.16$4.51958 million—about $51.46$22.51992 million in today’s dollars.
Then, some time in June 1958, Mr. Vicary disappeared from the New York marketing scene, reportedly leaving no bank accounts, no clothes in his closet, and no hint as to where he might have gone. The big advertisers, apparently ashamed of having been fooled by such an obvious scam, have said nothing since about subliminal advertising, except to deny that they have ever used it.
2012-plotnick.pdf: “At the Interface: The Case of the Electric Push Button, 1880–1923”, (2012-10-01; ):
[JSTOR Today discussion:
The doorbell. The intercom. The elevator. Once upon a time, beginning in the late 19th century, pushing the button that activated such devices was a strange new experience. The electric push button, the now mundane-seeming interface between human and machine, was originally a spark for wonder, anxiety, and social transformation.
As media studies scholar Rachel Plotnick details, people worried that the electric push button would make human skills atrophy. They wondered if such devices would seal off the wonders of technology into a black box: “effortless, opaque, and therefore unquestioned by consumers.” Today, you’d probably have to schedule an electrician to fix what some children back then knew how to make: electric bells, buttons, and buzzers.
“Some believed that users should creatively interrogate these objects and learn how they worked as part of a broader electrical education”, Plotnick explains. “Others…suggested that pushing buttons could help users to avoid complicated and laborious technological experiences. These approaches reflected different groups’ attempts at managing fears of electricity.”
… Between 1880 and 1920, hundreds of patent applications were made for “electric buttons” or “push-buttons.”
At the end of the 19th century, many laypeople had a “working knowledge not only of electricity, but also of the buttons they pushed and the relationship between the 2”, according to Plotnick. Those who promoted electricity and sold electrical devices, however, wanted push-button interfaces to be “simplistic and worry-free.” They thought the world needed less thinking though and tinkering, and more automatic action. “You press the button, we do the rest”—the Eastman Company’s famous slogan for Kodak cameras—could be taken as the slogan for an entire way of life.
Ultimately, the idea that electricity was a kind of magic would triumph over a more hands-on, demystifying approach.
Plotnick quotes an educator and activist from 1916 lamenting that pushing a button “seems to relieve one of any necessity for responsibility about what goes on behind the button.” That resonates now, more than a century later, when technology is even more complicated and even more intimately entwined with our lives. The “black box” reigns supreme.]
“The Sisyphean Cycle of Technology Panics”, (2020-06-30):
Widespread concerns about new technologies—whether they be novels, radios, or smartphones—are repeatedly found throughout history. Although tales of past panics are often met with amusement today, current concerns routinely engender large research investments and policy debate. What we learn from studying past technological panics, however, is that these investments are often inefficient and ineffective. What causes technological panics to repeatedly reincarnate? And why does research routinely fail to address them? To answer such questions, I examined the network of political, population, and academic factors driving the Sisyphean cycle of technology panics. In this cycle, psychologists are encouraged to spend time investigating new technologies, and how they affect children and young people, to calm a worried population. Their endeavor, however, is rendered ineffective because of the lack of a theoretical baseline; researchers cannot build on what has been learned researching past technologies of concern. Thus, academic study seemingly restarts for each new technology of interest, which slows down the policy interventions necessary to ensure technologies are benefiting society. In this article, I highlight how the Sisyphean cycle of technology panics stymies psychology’s positive role in steering technological change and the pervasive need for improved research and policy approaches to new technologies.
[Keywords: digital-technology use, social media, screen time, well-being, adolescents]
2018-hendry.pdf: “The Contemporary Evolution of Fitness”, (2018-01-01; ):
The rate of evolution of population mean fitness informs how selection acting in contemporary populations can counteract environmental change and genetic degradation (mutation, gene flow, drift, recombination). This rate influences population increases (e.g., range expansion), population stability (e.g., cryptic eco-evolutionary dynamics), and population recovery (i.e., evolutionary rescue). We review approaches for estimating such rates, especially in wild populations. We then review empirical estimates derived from two approaches: mutation accumulation (MA) and additive genetic variance in fitness (IAw). MA studies inform how selection counters genetic degradation arising from deleterious mutations, typically generating estimates of <1% per generation. IAw studies provide an integrated prediction of proportional change per generation, nearly always generating estimates of <20% and, more typically, <10%. Overall, considerable, but not unlimited, evolutionary potential exists in populations facing detrimental environmental or genetic change. However, further studies with diverse methods and species are required for more robust and general insights.
2015-polderman.pdf: “Meta-analysis of the heritability of human traits based on fifty years of twin studies”, (2015-05-18; ):
Despite a century of research on complex traits in humans, the relative importance and specific nature of the influences of genes and environment on human traits remain controversial. We report a meta-analysis of twin correlations and reported variance components for 17,804 traits from 2,748 publications including 14,558,903 partly dependent twin pairs, virtually all published twin studies of complex traits. Estimates of heritability cluster strongly within functional domains, and across all traits the reported heritability is 49%. For a majority (69%) of traits, the observed twin correlations are consistent with a simple and parsimonious model where twin resemblance is solely due to additive genetic variation. The data are inconsistent with substantial influences from shared environment or non-additive genetic variation. This study provides the most comprehensive analysis of the causes of individual differences in human traits thus far and will guide future gene-mapping efforts. All the results can be visualized using the MaTCH webtool.
2006-nettle.pdf: “The evolution of personality variation in humans and other animals”, (2006-09-01; ):
A comprehensive evolutionary framework for understanding the maintenance of heritable behavioral variation in humans is yet to be developed. Some evolutionary psychologists have argued that heritable variation will not be found in important, fitness-relevant characteristics because of the winnowing effect of natural selection. This article propounds the opposite view. Heritable variation is ubiquitous in all species, and there are a number of frameworks for understanding its persistence. The author argues that each of the Big Five dimensions of human personality can be seen as the result of a trade-off between different fitness costs and benefits. As there is no unconditionally optimal value of these trade-offs, it is to be expected that genetic diversity will be retained in the population.
“The Evolutionary Genetics of Personality”, (2007-04-27):
Genetic influences on personality differences are ubiquitous, but their nature is not well understood. A theoretical framework might help, and can be provided by evolutionary genetics.
We assess three evolutionary genetic mechanisms that could explain geneticin personality differences: selective neutrality, mutation-selection balance, and balancing selection. Based on evolutionary genetic theory and empirical results from behaviour genetics and personality psychology, we conclude that selective neutrality is largely irrelevant, that mutation-selection balance seems best at explaining genetic in intelligence, and that balancing selection by environmental heterogeneity seems best at explaining genetic in personality traits. We propose a general model of heritable personality differences that conceptualises intelligence as fitness components and personality traits as individual reaction norms of genotypes across environments, with different fitness consequences in different environmental niches. We also discuss the place of mental health in the model.
This evolutionary genetic framework highlights the role of gene-environment interactions in the study of personality, yields new insight into the person-situation-debate and the structure of personality, and has practical implications for both quantitative and molecular genetic studies of personality.
[Keywords: evolutionary psychology, personality differences, behaviour genetics, intelligence, personality traits, gene-environment interactions, mutation load, mutation-selection balance, mutational cross-section, epistasis, frequency-dependent selection]
“The Evolutionary Genetics of Personality Revisited”, (2016-02):
- Evolutionary forces that maintain genetic in traits can be inferred from their genetic architecture and fitness correlates.
- A substantial amount of new data on the genomics and reproductive success associated with personality traits and intelligence has recently become available.
- Intelligence differences seem to have been selected for robustness against mutations.
- Human tendencies to select, create and adapt to environments might support the maintenance of personality traits through balancing selection.
Like all human individual differences, personality traits and intelligence are substantially heritable. From an evolutionary perspective, this poses the question what evolutionary forces maintain their genetic variation. Information about the genetic architecture and associations with evolutionary fitness permit inferences about these evolutionary forces. As our understanding of the genomics of personality and its associations with reproductive success have grown considerably in recent years, it is time to revisit this question. While mutations clearly affect the very low end of the intelligence continuum, individual differences in the normal intelligence range seem to be surprisingly robust against mutations, suggesting that they might have been canalized to withstand such perturbations. Most personality traits, by contrast, seem to be neither neutral to selection nor under consistent directional or stabilizing selection. Instead evidence is in line with balancing selection acting on personality traits, probably supported by human tendencies to seek out, construct and adapt to fitting environments.
2010-kelly-whattechnologywants-ch11-lessonsofamishhackers.pdf: “What Technology Wants: Chapter 11, Lessons of AMish Hackers”, Kevin Kelly
- Triangulation across the results from genetically informative designs supports the existence of causal effects of exercise on mental health as well as residual confounding by genetic factors that independently influence participation in regular exercise and mental health outcomes.
- A model explaining the heritability of voluntary exercise behaviour in terms of genetic moderation of its positive mental health effects can explain how causal effects co-exist with genetic pleiotropy.
- The model calls for further research with strategies that use genomic information to improve the success of interventions on regular exercise behaviour.
Regular exercise is associated with mental health throughout the life course but the chain-of-causality underlying this association remains contested. I review results from genetically informative designs that examine causality, including the discordant monozygotic twin design, multivariate genetic models, Mendelian Randomization, and stratification on polygenic risk scores. Triangulation across the results from these and the standard designs for causal inference (RCT, prospective studies) in the extant literature supports the existence of causal effects of exercise on mental health as well as residual confounding by genetic factors that independently influence participation in regular exercise and mental health outcomes. I present an update of our earlier model for the genetic determinants of voluntary exercise behaviour. The model allows causal effects of regular exercise on mental health to co-exist with genetic pleiotropy through differences in the genetic sensitivity to the mental health benefits of exercise. The model encourages research on strategies that use genomic information to improve the success of interventions on regular exercise behaviour.
[Keywords: twin study, Mendelian randomization, polygenic risk score, exercise psychology, personalized medicine]
2020-xu.pdf: “Analysis of genetic and environmental correlation between leisure activities and cognitive function in aging Chinese twins”, (2020-12-09; ):
Objective: Leisure activity has been shown to be beneficial to mental health and cognitive aging. The biological basis of the correlation is, however, poorly understood. This study aimed at exploring the genetic and environmental impacts on correlation between leisure activities and cognitive function in the Chinese middle-aged and old-aged twins.
Methods: Cognition measured using a screening test (Montreal Cognitive Assessment, MoCA) and leisure activities including intellectual and social activity were investigated on 379 complete twin pairs of middle-aged and old-aged twins. Univariate and bivariate twin models were fitted to estimate the genetic and environmental components in theirand covariance.
Results: Moderate heritability was estimated for leisure activities and cognition (0.44–0.53) but insignificant for social activity. Common environmental factors accounted for about 0.36 of the total statistically-significant unique environmental correlation (rE = 0.12).to social activity with no statistically-significant contribution to leisure activity, intellectual activity and cognition. Unique environmental factors displayed moderate contributions (0.47–0.64) to leisure activities and cognition. Bivariate analysis showed highly and positively between leisure activities and cognition (rg = 0.80–0.96). Besides, intellectual activity and cognition presented low but
Conclusions: Genetic factor had the moderate contribution to leisure activities and cognition. Cognitive function was highly genetically related to leisure activities. Intellectual activity and cognitive function may share some unique environmental basis.
[Keywords: Classical twin method,, cognitive function, intellectual activity, social activity, leisure activities]
2014-deryakulu.pdf: “Genetic and environmental influences on problematic Internet use: A twin study”, Deniz Deryakulu, Ömer Faruk Ursavaş
2015-vink.pdf: “Heritability of compulsive Internet use in adolescents”, Jacqueline M. Vink, Toos C. E. M. Beijsterveldt, Charlotte Huppertz, Meike Bartels, Dorret I. Boomsma
2017-hahn.pdf: “Internet addiction and its facets: The role of genetics and the relation to self-directedness”, Elisabeth Hahn, Martin Reuter, Frank M. Spinath, Christian Montag
2014-li.pdf: “A Twin Study of Problematic Internet Use: Its Heritability and Genetic Association With Effortful Control”, (2014-08-01; ):
Our goal was to estimate genetic and environmental sources of influence on adolescent problematic internet use, and whether these individual differences can be explained by effortful control, an important aspect of self-regulation. A sample of 825 pairs of Chinese adolescent twins and their parents provided reports of problematic internet use and effortful control. Univariate analysis revealed that genetic factors explained 58–66% ofin problematic internet use, with the rest explained by non-shared environmental factors. Sex difference was found, suggesting boys’ problematic internet use was more influenced by genetic influences than girls’ problematic internet use. Bivariate analysis indicated that effortful control accounted for a modest portion of the genetic and non-shared environmental variance in problematic internet use among girls. In contrast, among boys, effortful control explained between 6% (parent report) and 20% (self-report) of in problematic internet use through overlapping genetic pathways. Adolescent problematic internet use is heritable, and poor effortful control can partly explain adolescent problematic internet use, with effects stronger for boys. Implications for future research are discussed.
Excessive internet use has been linked to psychopathology. Therefore, understanding the genetic and environmental risks underpinning internet use and their relation to psychopathology is important. This study aims to explore the genetic and environmental etiology of internet use measures and their associations with internalizing disorders and substance use disorders. The sample included 2,059 monozygotic (MZ) and dizygotic (DZ) young adult twins from the Brisbane Longitudinal Twin Study (BLTS). Younger participants reported more frequent internet use, while women were more likely to use the internet for interpersonal communication. Familial aggregation in ‘frequency of internet use’ was entirely explained by additive genetic factors accounting for 41% of the . Familial aggregation in ‘frequency of use after 11 pm’, ‘using the internet to contact peers’, and ‘using the internet primarily to access social networking sites’ was attributable to varying combinations of additive genetic and shared environmental factors. In terms of psychopathology, there were no statistically-significant associations between internet use measures and major depression (MD), but there were positive statistically-significant associations between ‘frequency of internet use’ and ‘frequency of use after 11 pm’ with social phobia (SP). ‘Using the internet to contact peers’ was positively associated with alcohol abuse, whereas ‘using the internet to contact peers’ and ‘using the internet primarily to access social networking sites’ were negatively associated with cannabis use disorders and nicotine symptoms. Individual differences in internet use can be attributable to varying degrees of genetic and environmental risks. Despite some associations of small effect, variation in internet use appears mostly unrelated to psychopathology.
Online media use has become an increasingly important behavioral domain over the past decade. However, studies into the etiology of individual differences in media use have focused primarily on pathological use. Here, for the first time, we test the genetic influences on online media use in a UK representative sample of 16 year old twins, who were assessed on time spent on educational (n = 2,585 twin pairs) and entertainment websites (n = 2,614 twin pairs), time spent gaming online (n = 2,635 twin pairs), and Facebook use (n = 4,333 twin pairs). Heritability was substantial for all forms of online media use, ranging from 34% for educational sites to 37% for entertainment sites and 39% for gaming. Furthermore, genetics accounted for 24% of thein Facebook use. Our results support an active model of the environment, where young people choose their online engagements in line with their genetic propensities.
2012-kirzinger.pdf: “Genetic and Environmental Influences on Media Use and Communication Behaviors”, (2014-04-01; ):
A great deal of scholarly work has explored the motivations behind media consumption and other various communication traits. However, little research has investigated the sources of these motivations and virtually no research considers their potential genetic underpinnings. Drawing on the field of behavior genetics, we use a classical twin design study to examine the genetic and environmental influences on nine communication behaviors. Our findings indicate a substantial portion of the totalin media habits can be attributed to genes, as much as one-third of the in some instances. Mass communication scholars would benefit by paying closer attention to heritability when thinking about the causes as well as the consequences of media traits in contemporary society.
2012-miller.pdf: “The heritability and genetic correlates of mobile phone use: a twin study of consumer behavior”, (2012-01-01; ):
There has been almost no overlap between behavior genetics and consumer behavior research, despite each field’s importance in understanding society. In particular, both have neglected to study genetic influences on consumer adoption and usage of new technologies—even technologies as important as the mobile phone, now used by 5.8 out of 7.0 billion people on earth. To start filling this gap, we analyzed self-reported mobile phone use, intelligence, and personality traits in two samples of Australian teenaged twins (mean ages 14.2 and 15.6 years), totaling 1,036 individuals. ACE modeling using Mx software showed substantial heritabilities for how often teens make voice calls (.60 and .34 in samples 1 and 2, respectively) and for how often they send text messages (.53 and. 50). Shared family environment—including neighborhood, social class, parental education, and parental income (i.e., the generosity of calling plans that parents can afford for their teens)—had much weaker effects. Multivariate modeling based on cross-twin, cross-trait correlations showed negative between talking/texting frequency and intelligence (around –.17), and positive genetic correlations between talking/texting frequency and extraversion (about .20 to .40). Our results have implications for assessing the risks of mobile phone use such as radiofrequency field (RF) exposure and driving accidents, for studying adoption and use of other emerging technologies, for understanding the genetic architecture of the cognitive and personality traits that predict consumer behavior, and for challenging the common assumption that consumer behavior is shaped entirely by culture, media, and family environment.
Although music is a universal feature of human culture, little is known about its origins and functions. A prominent theory of music evolution is the sexual selection hypothesis, which proposes that music evolved as a signal of genetic quality to potential mates. The hypothesis offers several empirically testable predictions. First, musically skilled and active individuals should have greater mating success than less-skilled individuals. Second, if musical ability functions as an indicator of genetic quality, it is expected to be associated with other traits putatively related to genetic quality. Third, associations as per the first and second predictions are expected to be at least partly due to overlapping genetic influences. We tested these predictions in a large genetically informative sample of 10,975 Swedish twin individuals aged between 27 and 54 years (M = 40.1, SD = 7.7), using musical aptitude and music achievement as measures of musical ability. To assess mating success we examined number of sex-partners, age of first intercourse, sociosexuality, and number of offspring. General intelligence, simple reaction time, and height were used to investigate relationships with traits putatively related to genetic quality. Twin modeling showed moderate genetic influences on musical aptitude for both sexes (heritability estimates were 38% for males and 51% for females). Music achievement was also moderately influenced by genetic influences in males (heritability = 57%), but the genetic influences were low and nonsignificant for females (heritability = 9%). Contrary to predictions, the majority of phenotypic associations between musical ability and music achievement with mating success were nonsignificant or in the other direction, with those with greater musical ability scoring lower on the measures of mating success. Genetic correlations between these measures were also nonsignificant. Most correlations of musical aptitude and music achievement with genetic quality measures were , including correlations with general intelligence, simple reaction time, and, in females, height (but only for aptitude). However, only the correlation between musical aptitude and general intelligence in men was statistically-significantly driven by overlapping genetic influences. Our findings provide little support for a role of sexual selection in the evolution of musical ability. Alternative explanations and limitations are discussed.
2015-butkovic.pdf: “Personality related traits as predictors of music practice: Underlying environmental and genetic influences”, Ana Butkovic, Fredrik Ullén, Miriam A. Mosing
“Musical Aptitude Is Associated with AVPR1A-Haplotypes”, (2009-05-20):
Artistic creativity forms the basis of music culture and music industry. Composing, improvising and arranging music are complex creative functions of the human brain, which biological value remains unknown. We hypothesized that practicing music is social communication that needs musical aptitude and even creativity in music. In order to understand the neurobiological basis of music in human evolution and communication we analyzed polymorphisms of the arginine vasopressin receptor 1A (AVPR1A), serotonin transporter (SLC6A4), catecol-O-methyltranferase (COMT), dopamine receptor D2 (DRD2) and tyrosine hydroxylase 1 (TPH1), genes associated with social bonding and cognitive functions in 19 Finnish families (n = 343 members) with professional musicians and/or active amateurs. All family members were tested for musical aptitude using the auditory structuring ability test (Karma Music test; KMT) and Carl Seashores tests for pitch (SP) and for time (ST). Data on creativity in music (composing, improvising and/or arranging music) was surveyed using a web-based questionnaire. Here we show for the first time that creative functions in music have a strong genetic component (h2 = 0.84; composing h2 = 0.40; arranging h2 = 0.46; improvising h2 = 0.62) in Finnish multigenerational families. We also show that high music test scores are statistically-significantly associated with creative functions in music (p < 0.0001). We discovered an overall haplotype association with AVPR1A gene (markers RS1 and RS3) and KMT (p = 0.0008; corrected p = 0.00002), SP (p = 0.0261; corrected p = 0.0072) and combined music test scores (COMB) (p = 0.0056; corrected p = 0.0006). AVPR1A haplotype AVR+RS1 further suggested a positive association with ST (p = 0.0038; corrected p = 0.00184) and COMB (p = 0.0083; corrected p = 0.0040) using haplotype-based association test HBAT. The results suggest that the neurobiology of music perception and production is likely to be related to the pathways affecting intrinsic attachment behavior.
[Note that the candidate-gene hits here are highly dubious.]
1954-cattell.pdf: “Musical Preferences and Personality Diagnosis: I. A Factorization of One Hundred and Twenty Themes”, (1954; ):
Probably the first sustained attempt to explore the value of music as therapy was made by a group of psychiatrists at the Walter Reed Hospital, during World War II, under the stimulus of the large number of psychiatric casualties requiring treatment. This first pragmatic approach has fortunately been developed into a more permanent research organization by one of the participants, Miss Paperte, in her creation of the Music Research Foundation. The present article proposes to review very briefly the nascent research in this area and to set out the results of a 3-year research project supported partly by the Music Research Foundation and partly by the Graduate School of the University of Illinois.
…The aim of the research report in this and 2 succeeding articles9, 10, sustained partly by the author’s own research resources and partly by the Bonfils Fellowship and other assistance from the Musical Research Foundation, has been to investigate relations between musical choice and personality, in normal and pathological subjects. Secondarily, it aims to produce a music choice test for personality diagnosis11.
…A preliminary list of 200 musical excerpts, from different periods, countries, and styles was tried out with about 50 students and was cut down to 120 by eliminating any piece which seemed very similar to any other or which for some peculiar reason of instrument or period was deemed likely to be unreliable. We then arranged for a skilled pianist to record the 120 excerpts on piano, since we wished to eliminate any chance effects which might be due to cultural attachments of the subjects to particular instruments.
…Factorization of like and dislike reactions to 120 musical excerpts by a population of 196 “normal” men and women in early maturity has yielded 12 factors, 8 of which are confirmed by 2 independent rotations of the material, one more moderately confirmed, and 3 awaiting further research.
Although the definition and soundness of simple structure for these factors is of a high order, little attempt has been made here to infer their nature from the particular association of musical likes and dislikes connected with them, though in some cases “hunches” indicated by the data are mentioned. Our general hypothesis that these independent dimensions of choice will turn out to be personality and temperament factors rather than patterns of specific musical content or school seems sufficiently sustained.
Research leading to more extensive interpretation of the psychological meaning of the factors should be possible now that I.P.A.T. has made the above excerpts available on a single, 12 ins. long-playing record11. Our own interpretations will wait on our use of this instrument in research directed to relating these factors to measured personality factors and pathological syndromes.
2010-hatemi.pdf: “Not by Twins Alone: Using the Extended Family Design to Investigate Genetic Influence on Political Beliefs”, (2020-07-01; ):
Variance components estimates of political and social attitudes suggest a substantial level of genetic influence, but the results have been challenged because they rely on data from twins only. In this analysis, we include responses from parents and nontwin full siblings of twins, account for measurement error by using a panel design, and estimate genetic and environmental by maximum-likelihood structural equation modeling. By doing so, we address the central concerns of critics, including that the twin-only design offers no verification of either the equal environments or random mating assumptions. Moving beyond the twin-only design leads to the conclusion that for most political and social attitudes, genetic influences account for an even greater proportion of individual differences than reported by studies using more limited data and more elementary estimation techniques. These findings make it increasingly difficult to deny that—however indirectly—genetics plays a role in the formation of political and social attitudes.
2011-conway.pdf: “The Biological Roots of Complex Thinking: Are Heritable Attitudes More Complex?”, (2011-02-01; ):
Are highly heritable attitudes more or less complex than less heritable attitudes? Over 2,000 participant responses on topics varying in heritability were coded for overall integrative complexity and its 2 subcomponents (dialectical complexity and elaborative complexity). Across different heritability sets drawn from 2 separate prior twin research programs, the present results yielded a consistent pattern: Heritability was always statistically-significantly positively correlated with integrative complexity. Further analyses of the subcomponents suggested that the manner in which complexity was expressed differed by topic type: For societal topics, heritable attitudes were more likely to be expressed in dialectically complex terms, whereas for personally involving topics, heritable attitudes were more likely to be expressed in elaboratively complex terms. Most of these relationships remained even when controlling for measurements of attitude strength. The authors discuss the genetic roots of complex versus simple attitudes, implications for understanding attitude development more broadly, and the contribution of these results to previous work on both heritability and complexity.
2014-piffer.pdf: “Heritability of Creative Achievement”, (2014-05-08; ):
Although creative achievement is a subject of much attention to lay people, the origin of individual differences in creative accomplishments remain poorly understood.
This study examined genetic and environmental influences on creative achievement in an adult sample of 338 twins (mean age = 26.3 years; SD = 6.6 years). Twins completed the Creative Achievement Questionnaire (CAQ) that assesses observable creative accomplishments in various domains. The CAQ includes Artistic Creative Achievement (ACA), Scientific Creative Achievement (SCA), and the Total Creative Achievement (TCA) scales.
Across all 3 scales, monozygotic twin correlations were consistently and substantially higher than dizygotic twin correlations, suggesting the importance of genetic influences on creative achievements. Heritability estimates for the 3 scales ranged from 43% to 67%, with the remainingbeing attributable to nonshared environmental influences plus measurement error. The effects of shared environmental factors were negligible.
These results were in contrast with those of early twin studies of creativity, which yielded aamount of shared family environmental influences. Discrepancies in findings between this study and investigations may be due in part to the differences in ages of twins and measures.
Creativity is the tendency to generate or recognize ideas, alternatives, or possibilities. Following a study on the genetic contribution to working in a creative profession, based on polygenic score analysis, we report the total heritability of this trait in a large sample of adult twins and their siblings registered with the Netherlands Twin Register. Data from 6755 twins and 1817 siblings were analyzed using genetic structural equation modeling. Working in a creative profession is relatively rare in our sample (2.6% of twins and 3.2% of siblings). Twin correlations (identical 0.68 and fraternal 0.40) commended a model with additive genetic factors (full model estimate 0.56), shared (full model estimate 0.12), and unique environmental factors (full model estimate 0.32). Genetic model fitting resulted in a best-fitting model existing of additive genetic factors and unique environmental factors, resulting in a heritability of 0.70.
Political participation (POP), social participation (SOP), and political interest (PI) are important indicators of social status and social inequality. Previous studies on related trait differences yielded genetic and environmental contributions. However, focusing on adult samples, classical twin designs, and convenience samples often restricts parameter estimation and generalizability, and limits the understanding of age differences. We investigated sources of in POP, SOP, and PI in late adolescence and early adulthood with an extended twin family design (ETFD). We analyzed data from over 2,000 representative German twin families. Individual environments not shared by family members reflected the major source of for all variables, but genetic influences were also pronounced. Genetic effects were mostly higher for young adults, whereas effects of twins’ shared environment were in adolescence. Our study deepens the understanding of the interplay between genetic and environmental factors in shaping differences in young persons’ integration in society.
2020-york.pdf: “Exploring Genetic Contributions to News Use Motives and Frequency of News Consumption: A Study of Identical and Fraternal Twins”, (2020-05-27; ):
Prior research conducted within the Uses and Gratifications paradigm has considered the contribution of numerous background social and psychological characteristics to motives for media use and media consumption patterns. In this study, we explore the extent to which far more fundamental characteristics—genes—explain, in part, motives to use news media and frequency of news use. Utilizing original data collected on identical and fraternal twins (n = 334), we find that latent genetic traits explain a nontrivial amount of CNN.in two unique news use motives, surveillance and entertainment, as well as frequency of consumption across multiple news sources. Genetic traits were particularly influential in explaining the frequency of using sources commonly characterized as ideological, such as Fox News and
1993-lykken.pdf: “Heritability of interests: a twin study”, (1993; ):
The authors administered inventories of vocational and recreational interests and talents to 924 pairs of twins who had been reared together and to 92 pairs separated in infancy and reared apart. Factor analysis of all 291 items yielded 39 identifiable factors and 11 superfactors. The data indicated that about 50% of interests (about two thirds of the stable variance) was associated with genetic variation. The authors show that heritability can be conservatively estimated from the within-pair correlations of adult monozygotic twins reared together. Evidence for nonadditive genetic effects on interests may explain why heritability estimates based on family studies are so much lower. The authors propose a model in which precursor traits of aptitude and personality, in part genetically determined, guide the development of interests through the mechanisms of gene-environment correlation and interaction.
Dogs were the first domesticated animal and, according to the archaeological evidence, have had a close relationship with humans for at least 15,000 years. Today, dogs are common pets in our society and have been linked to increased well-being and improved health outcomes in their owners. A dog in the family during childhood is associated with ownership in adult life. The underlying factors behind this association could be related to experiences or to genetic influences. We aimed to investigate the heritability of dog ownership in a large twin sample including all twins in the Swedish Twin Registry born between 1926 and 1996 and alive in 2006. Information about dog ownership was available from 2001 to 2016 from national dog registers. The final data set included 85,542 twins from 50,507 twin pairs with known zygosity, where information on both twins were available in 35,035 pairs. Structural equation modeling was performed to estimate additive genetic effects (the heritability), common/shared environmental, and unique/non-shared environmental effects. We found that additive genetic factors largely contributed to dog ownership, with heritability estimated at 57% for females and 51% for males. An effect of shared environmental factors was only observed in early adulthood. In conclusion, we show a strong genetic contribution to dog ownership in adulthood in a large twin study. We see two main implications of this finding: (1) genetic variation may have contributed to our ability to domesticate dogs and other animals and (2) potential pleiotropic effects of genetic variation affecting dog ownership should be considered in studies examining health impacts of dog ownership.
There is growing evidence that pet ownership and human-animal interaction (HAI) have benefits for human physical and psychological well-being. However, there may be pre-existing characteristics related to patterns of pet ownership and interactions with pets that could potentially bias results of research on HAI. The present study uses a behavioral genetic design to estimate the degree to which genetic and environmental factors contribute to individual differences in frequency of play with pets among adult men. Participants were from the ongoing longitudinal Vietnam Era Twin Study of Aging (VETSA), a population-based sample of 1,237 monozygotic (MZ) and dizygotic (DZ) twins aged 51–60 years. Results demonstrate that MZ twins have higher correlations than DZ twins on frequency of pet play, suggesting that genetic factors play a role in individual differences in interactions with pets. Structural equation modeling revealed that, according to the best model, genetic factors accounted for as much as 37% of the in pet play, although the majority of (63-71%) was due to environmental factors that are unique to each twin. Shared environmental factors, which would include childhood exposure to pets, overall accounted for <10% of the in adult frequency of pet play, and were not . These results suggest that the effects of childhood exposure to pets on pet ownership and interaction patterns in adulthood may be mediated primarily by genetically-influenced characteristics.
2020-vink.pdf: “Causes of Variation in Food Preference in the Netherlands”, (2020-09-04; ):
Our current society is characterized by an increased availability of industrially processed foods with high salt, fat and sugar content. How is it that some people prefer these unhealthy foods while others prefer more healthy foods? It is suggested that both genetic and environmental factors play a role. The aim of this study was to (1) identify food preference clusters in the largest twin-family study into food preference to date and (2) determine the relative contribution of genetic and environmental factors to individual differences in food preference in the Netherlands. Principal component analysis was performed to identify the preference clusters by using data on food liking/disliking from 16,541 adult multiples and their family members. To estimate the heritability of food preference, the data of 7833 twins were used in. We identified seven food preference clusters (Meat, Fish, Fruits, Vegetables, Savory snacks, Sweet snacks and Spices) and one cluster with Drinks. Broad-sense heritability (additive [A] + dominant [D] genetic factors) for these clusters varied between 0.36 and 0.60. Dominant genetic effects were found for the clusters Fruit, Fish (males only) and Spices. Quantitative sex differences were found for Meat, Fish and Savory snacks and Drinks. To conclude, our study convincingly showed that genetic factors play a substantial role in food preference. A next important step is to identify these genes because genetic vulnerability for food preference is expected to be linked to actual food consumption and different diet-related disorders.
To learn more about the mechanisms of human dietary fat perception, 398 human twins rated fattiness and liking for six types of potato chips that differed in triglyceride content (2.5, 5, 10, and 15% corn oil); reliability estimates were obtained from a subset (n = 50) who did the task twice. Some chips also had a saturated long-chain fatty acid (hexadecanoic acid, 16:0) added (0.2%) to evaluate its effect on fattiness and liking. We computed the heritability of these measures and conducted a genome-wide association study (GWAS) to identify regions of the genome that co-segregate with fattiness and liking. Perceived fattiness and liking for the potato chips were reliable (r = 0.31-0.62, p < 0.05) and heritable (up to h2 = 0.29, p < 0.001, for liking). Adding hexadecanoic acid to the potato chips significantly increased ratings of fattiness but decreased liking. Twins with the G allele of rs263429 near GATA3-AS1 or the G allele of rs8103990 within ZNF729 reported more liking for potato chips than did twins with the other allele (multivariate , p < 1×10-5), with results reaching genome-wide suggestive but not significance criteria. Person-to-person variation in the perception and liking of dietary fat was (a) negatively affected by the addition of a saturated fatty acid and (b) related to inborn genetic variants. These data suggest liking for dietary fat is not due solely to fatty acid content and highlight new candidate genes and proteins within this sensory pathway.
2018-jamnik.pdf: “A Multimethodological Study of Preschoolers' Preferences for Aggressive Television and Video Games”, Matthew R. Jamnik
Background: Twin studies offer a ‘natural experiment’ that can estimate the magnitude of environmental and genetic effects on a target phenotype. We hypothesised that fidgetiness and enjoyment of activity would be heritable but that objectively-measured daily activity would show a strong shared environmental effect.
Methodology/Principal Findings: In a sample of 9–12 year-old same-sex twin pairs (234 individuals; 57 MZ, 60 DZ pairs) we assessed three dimensions of physical activity: (1) objectively-measured physical activity using accelerometry, (2) ‘fidgetiness’ using a standard psychometric scale, and (3) enjoyment of physical activity from both parent ratings and children’s self-reports. Shared environment effects explained the majority (73%) of the confidence intervals ( ): 0.63–0.81) with a smaller unshared environmental effect (27%; : 0.19–0.37) and no genetic effect. In contrast, fidgetiness was primarily under genetic control, with additive genetic effects explaining 75% ( : 62–84%) of the variance, as was parent’s report of children’s enjoyment of low 74% ( : 61–82%), medium 80% ( : 71–86%), and high impact activity (85%; : 78–90%), and children’s expressed activity preferences (60%, : 42–72%).in objectively-measured total physical activity (95%
Conclusions: Consistent with our hypothesis, the shared environment was the dominant influence on children’s day-to-day activity levels. This finding gives a strong impetus to research into the specific environmental characteristics influencing children’s activity, and supports the value of interventions focused on home or school environments.
Social cognitive models of health behavior propose that individual differences in leisure time exercise behavior are influenced by the attitudes towards exercise. At the same time, large scale twin-family studies show a large influence of genetic factors on regular exercise behavior.
This twin-sibling study aimed to unite these findings by demonstrating that exercise attitudes can be heritable themselves. Secondly, the genetic and environmental cross-trait correlations and the monozygotic (MZ) twin intrapair differences model were used to test whether the association between exercise attitudes and exercise behavior can be causal. Survey data were obtained from 5,095 twins and siblings (18–50 years).
A genetic contribution was found for exercise behavior (50% in males, 43% in females) and for the 6 exercise attitude components derived from principal component analysis: perceived benefits (21, 27%), lack of skills, support and/or resources (45, 48%), time constraints (25, 30%), lack of energy (34, 44%), lack of enjoyment (47, 44%), and embarrassment (42, 49%). These components were predictive of leisure time exercise behavior (R2 = 28%). Bivariate modeling further showed that all the genetic (0.36 < |rA| < 0.80) and all but 2 unique environmental (0.00 < |rE| < 0.27) correlations between exercise attitudes and exercise behavior were statistically-significantly different from zero, which is a necessary condition for the existence of a causal effect driving the association. The correlations between the MZ twins’ difference scores were in line with this finding.
It is concluded that exercise attitudes and exercise behavior are heritable, that attitudes and behavior are partly correlated through pleiotropic genetic effects, but that the data are compatible with a causal association between exercise attitudes and behavior.
[Keywords: twin-sibling design, twins, correlational approach, physical activity, heritability]
Background: A sedentary lifestyle remains a major threat to health in contemporary societies. To get more insight in the relative contribution of genetic and environmental influences on individual differences in exercise participation, twin samples from seven countries participating in the GenomEUtwin project were used.
Methodology: Self-reported data on leisure time exercise behavior from Australia, Denmark, Finland, Norway, the Netherlands, Sweden and United Kingdom were used to create a comparable index of exercise participation in each country (60 minutes weekly at a minimum intensity of four metabolic equivalents).
Principal Findings: Modest geographical variation in exercise participation was revealed in 85,198 subjects, aged 19–40 years. Modeling of monozygotic and dizygotic twin resemblance showed that genetic effects play an important role in explaining individual differences in exercise participation in each country. Shared environmental effects played no role except for Norwegian males. Heritability of exercise participation in males and females was similar and ranged from 48% to 71% (excluding Norwegian males).
Conclusions: Genetic variation is important in individual exercise behavior and may involve genes influencing the acute mood effects of exercise, high exercise ability, high weight loss ability, and personality. This collaborative study suggests that attempts to find genes influencing exercise participation can pool exercise data across multiple countries and different instruments.
2009-stubbe.pdf: “Genetics of Exercise Behavior”, Janine H. Stubbe, Eco J. C. de Geus
Introduction: The aim of this study was to investigate the relative influence of genetic and environmental factors on children’s leisure time exercise behavior through the classic twin design.
Methods: Data were taken from The Netherlands Twin Register. The twins were 7 (n = 3966 subjects), 10 (n = 3562), and 12-yr-olds (n = 8687), with longitudinal data for 27% of the sample. Parents were asked to indicate the children’s regular participation in leisure time exercise activities, including frequency and duration. Resemblance between monozygotic and dizygotic twins for weekly MET-hours spent on exercise activities was analyzed as a function of their genetic relatedness.
Results: Average weekly MET-hours increased with age for both boys (age 7 yr: 14.0 (SD = 11.8); age 10 yr: 22.6 (SD = 18.7); age 12 yr: 28.4 (SD = 24.9)) and girls (age 7 yr: 9.7 (SD = 9.5); age 10 yr: 15.3 (SD = 15.1); age 12 yr: 19.3 (SD = 19.8)). Around 13% of boys and girls across all age groups did not participate in any regular leisure time exercise activities. Tracking of exercise behavior from age 7 to 12 yr was modest (0.168 < r < 0.534). For boys, genetic effects accounted for 24% (confidence interval, 18%-30%) of the at age 7 yr, 66% (53%-81%) at age 10 yr, and 38% (32%-46%) at age 12 yr. For girls, this was 22% (15%-30%), 16% (9%-24%), and 36% (30%-43%), respectively. Environmental influences shared by children from the same family explained 71%, 25%, and 50% of the in boys (age 7, 10, and 12 yr) and 67%, 72%, and 53% in girls. The shared environment influencing exercise behavior was partially different between boys and girls.
Conclusion: Our results stress the important role of shared environment for exercise behavior in young children.
Individual differences in adolescent exercise behavior are to a large extent explained by shared environmental factors. The aim of this study was to explore to what extent this shared environment represents effects of cultural transmission of parents to their offspring, generation specific environmental effects or assortative mating. Survey data on leisure-time exercise behavior were available from 3,525 adolescent twins and their siblings (13–18 years) and 3,138 parents from 1,736 families registered at the Netherlands Twin Registry. Data were also available from 5,471 adult twins, their siblings and spouses similar in age to the parents. Exercise participation (No/Yes, using a cut-off criterion of 4 metabolic equivalents and 60 min weekly) was based on questions on type, frequency and duration of exercise. A model to analyze dichotomous data from twins, siblings and parents including differences in variance decomposition across sex and generation was developed. Data from adult twins and their spouses were used to investigate the causes of mating (correlation between spouses = 0.41, due to phenotypic assortment). The heritability of exercise in the adult generation was estimated at 42%. The shared environment for exercise behavior in adolescents mainly represents generation specific shared environmental influences that seem somewhat more important in explaining familial clustering in girls than in boys (52 versus 41%). A small effect of vertical cultural transmission was found for boys only (3%). The remaining familial clustering for exercise behavior was explained by additive genetic factors (42% in boys and 36% in girls). Future studies on adolescent exercise behavior should focus on identification of the generation specific environmental factors.
Background: The health benefits of regular physical activity are well established. However, the relative contribution of heritable and environmental factors to physical activity participation remains controversial. Using a cut-point of 60 minutes of total activity per week, data from the GenomEUtwin project revealed consistent genetic influence on physical activity participation in 37,051 twin pairs from seven countries. We hypothesized that the heritability of physical activity participation would be attenuated using the CDC/ACSM recommended minimum threshold of 150 minutes of moderate intensity activity per week.
Methods: Data were obtained from 1,389 twin pairs from the community-based University of Washington Twin Registry. Twin similarity in physical activity participation using both cut-points was analyzed using tetrachoric correlations and structural equation modeling in all same-sex pairs.
Results: Correlations were higher in monozygotic (rMZ = 0.43, 95%= 0.33–0.54) than dizygotic pairs (rDZ = 0.30, 95% = 0.12–0.47) using the 60 minute cut-point. However, differences were attenuated using the 150 minute standard (rMZ = 0.30, 95% = 0.20–0.40; rDZ = 0.25, 95% = 0.07–0.42). Using the lower cut-point, the best fitting model of twin resemblance only included additive genetics and unique environment, with a heritability of 45%. In contrast, using the higher threshold, the best fitting model included the common and unique environment, with the unique environment contributing 72% of the .
Conclusion: Unique environment factors provide the strongest influence on physical activity participation at levels recommended for health benefits.
2018-schutte.pdf: “A twin study on the correlates of voluntary exercise behavior in adolescence”, (2019-01; ):
- The heritability of exercise behavior (EB) in young adults is substantial (60%–81%).
- Several parameters measured in adolescence were correlated with adult EB.
- These correlates showed genetic associations with adult EB.
- A large part of the covariation between EB and the correlates was due to genetic causes.
Objectives: To improve the success of interventions aimed to increase moderate to vigorous physical activity, we need to better understand the correlates of the extensive individual differences in voluntary exercise activities. Starting in adolescence, genetic effects become a dominant factor in explaining individual differences in voluntary exercise behavior. Here we aim to establish the prospective contribution of potential correlates of voluntary exercise behavior to its heritability.
Design: In a sample of adolescent and young adult twins, data on potential correlates of exercise behavior were collected using surveys (time point 1, n = 373) and a laboratory study (time point 2, n = 499). Information on personality, perceived barriers & benefits, subjective and objective exercise ability and the affective response to exercise were collected in a set of healthy adolescent twin pairs (16–18y) and their non-twin siblings (12–25y). Almost 3 years later, the subjects were sent an online follow-up survey on their current exercise status (time point 3, n = 423).
Methods: In bivariate models, the phenotypic (co)in these correlates and exercise behavior at all time points were decomposed in sources of genetic (co) and environmental (co) . The correlates that were statistically-significant associated with exercise behavior at time point 1 or 2 and showed statistically-significant to exercise behavior at time point 3 were used in 2 further analyses: Multiple regression analysis to predict exercise behavior at time point 3, and a genetic analysis in a common 2-factor model, that tested the overlap in genetic factors influencing these correlates and exercise behavior.
Results: Personality (Extraversion), perceived benefits and barriers, exercise-induced affective response (Energy measured after the cycling test), and subjective and objective exercise ability (VO2max) showed phenotypic and genetic association with exercise behavior at time point 3. The between the 2 factors in the common 2-factor model was 0.51, indicating that part of the heritability in exercise behavior derives from genetic variants that also influence these correlates.
Conclusions: Given their shared genetic basis and predictive power we assert that individual differences in extraversion, perceived benefits and barriers, exercise-induced feelings of energy, and subjective and objective exercise ability can be used to develop stratified interventions for adolescent and young adult exercise behavior. In addition, our results provide the first clues on ‘where to look’ for specific genetic variants for voluntary exercise behavior.
[Keywords: exercise behavior, heritability, personality, exercise ability, perceived benefits/barriers, affective response]
1981-kaprio.pdf: “Cigarette smoking, use of alcohol, and leisure-time physical activity among same-sexed adult male twins”, Jaako Kaprio, Markku Koskenvuo, Seppo Sarna
2010-aaltonen.pdf: “A longitudinal study on genetic and environmental influences on leisure time physical activity in the Finnish Twin Cohort”, (2010-01-01; ):
The purpose of this study was to examine changes in the contribution of genetic and environmental influences to leisure time physical activity among male and female twins over a 6-year follow-up. At baseline the sample comprised 4,280 monozygotic and 9,276 dizygotic twin individuals, and at follow-up 4,383 monozygotic and 9,439 dizygotic twin individuals. Participants were aged 18–54 years at baseline. Genetic modeling results showed that genetic influences on leisure time physical activity declined from baseline (44%) to follow-up (34%). Most of the genetic influences identified at baseline were present at followup (rg= 0.72). Specific environmental influences increased from baseline (56%) to follow-up (66%) while at follow-up new environmental time-specific influences were observed (re= 0.23). The model with sex differences showed a higher estimate of genetic influences for men than women both at baseline (men 47% vs. women 42%) and at follow-up (men 38% vs. women 31%). The additivefor this phenotype was greater for men (rg= 0.79) than women (rg= 0.64). The specific environmental influences were corresponding; at baseline men 53% and women 56% and at follow-up men 62% and women 69%. The environmental correlations between the two time points were similar for men (re= 0.21) and for women (re= 0.24). In conclusion, in a sample of healthy twins most of the genetic influences on leisure time physical activity expressed at baseline were present at 6 years of follow-up. New specific environmental factors underlying follow-up leisure time physical activity were observed.
1997-aarnio.pdf: “1997_sport_07_11.qxd”, cretu
The Chinese National Twin Registry (CNTR) currently includes data from 61 566 twin pair from 11 provinces or cities in China. Of these, 31 705, 15 060 and 13 531 pairs are monozygotic, same-sex dizygotic and opposite-sex dizygotic pairs, respectively, determined by opposite sex or intrapair similarity. Since its establishment in 2001, the CNTR has provided an important resource for analysing genetic and environmental influences on chronic diseases especially cardiovascular diseases. Recently, the CNTR has focused on collecting biologic specimens from disease-concordant or disease-discordant twin pairs or from twin pairs reared apart. More than 8000 pairs of these twins have been registered, and blood samples have been collected from more than 1500 pairs.
In this review, we summarize the main findings from univariate and multivariate genetic effects analyses, gene-environment interaction studies, omics studies exploring DNA methylation and metabolomic markers associated with phenotypes. There remains further scope for CNTR research and data mining. The plan for future development of the CNTR is described. The CNTR welcomes worldwide collaboration.
1994-koopmans.pdf: “Smoking and Sports Participation”, (1994-01-01; ):
It has long been recognized that both smoking and sports participation tend to cluster in families. In this chapter, we first describe the current status of smoking and sports participation as cardiovascular risk factors. After an outline of the principles of the quantitative genetic approaches to the analysis of individual differences in behaviour, we will review the literature on genetic and environmental determinants of smoking and sports participation. In the second half of this chapter, results from the Dutch Twin/Family Study of Health-Related Behavior are presented.
2002-maia.pdf: “Genetic factors in physical activity levels: A Twin Study”, (2002-08-01; ):
Background: Substantial interindividual variation is observed in sports participation and physical activity levels in youth. This study aimed to (1) estimate the relative contribution of genes, along with shared and nonshared environmental factors, to variation in sports participation index (SPI) and leisure-time physical activity (LTPA); and (2) test differences in those factors in males and females.
Methods: The sample was comprised of 411 Portuguese twin pairs of different zygosity aged 12 to 25 years. The SPI and LTPA were assessed with the Baecke questionnaire. Quantitative genetic modeling was used to test alternative models for the presence of additive gene effects (a2), common or shared environment within the family (c2), and unique environmental factors (e2).
Results: The best-fitting models showed sex-specific effects for the two phenotypes. Variance components for SPI in males were a2 = 68.4%, c2 = 20%, and e2 = 11.6%; and in females, a2 = 39.8%, c2 = 28.4%, and e2 = 31.8%. For variation in LTPA, genetic factors in males explained 63%, common environment was not , and unique environment explained 37%. In females, contributing factors were a2 = 32%, c2 = 38%, and e2 = 30%.
Conclusions: Genetic effects explained a considerable amount of variation in SPI and LTPA, which were greater in males than in females. The relevance of shared environmental factors (family and peers) and nonshared environmental factors in SPI and LTPA is particularly evident in females.
[Keywords: exercise, genetics, physical fitness, twins]
1976-loehlin-heredityenvironmentandpersonality.pdf: “Heredity, Environment, & Personality: A Study of 850 Sets of Twins”, (1976; ):
This volume reports on a study of 850 pairs of twins who were tested to determine the influence of heredity and environment on individual differences in personality, ability, and interests. It presents the background, research design, and procedures of the study, a complete tabulation of the test results, and the authors’ extensive analysis of their findings. Based on one of the largest studies of twin behavior ever conducted, the book challenges a number of traditional beliefs about genetic and environmental contributions to personality development.
The subjects were chosen from participants in the National Merit Scholarship Qualifying Test of 1962 and were mailed a battery of personality and interest questionnaires. In addition, parents of the twins were sent questionnaires asking about the twins’ early experiences. A similar sample of nontwin students who had taken the merit exam provided a comparison group. The questions investigated included how twins are similar to or different from non-twins, how identical twins are similar to or different from fraternal twins, how the personalities and interests of twins reflect genetic factors, how the personalities and interests of twins reflect early environmental factors, and what implications these questions have for the general issue of how heredity and environment influence the development of psychological characteristics. In attempting to answer these questions, the authors shed new light on the importance of both genes and environment and have formed the basis for new approaches in behavior genetic research.
Theories of skilled performance that emphasize training history, such as K. Anders Ericsson and colleagues’ deliberate-practice theory, have received a great deal of recent attention in both the scientific literature and the popular press. Twin studies, however, have demonstrated evidence for moderate-to-strong genetic influences on skilled performance. Focusing on musical accomplishment in a sample of over 800 pairs of twins, we found evidence for gene-environment correlation, in the form of a genetic effect on music practice. However, only about one quarter of the genetic effect on music accomplishment was explained by this genetic effect on music practice, suggesting that genetically influenced factors other than practice contribute to individual differences in music accomplishment. We also found evidence for gene-environment interaction, such that genetic effects on music accomplishment were most pronounced among those engaging in music practice, suggesting that genetic potentials for skilled performance are most fully expressed and fostered by practice.