Environmental Hereditarianism
Post updated, 9/13/14. See below!
I haven’t always made it explicit, but some of you might gather that I am rather hard on most “environmental” explanations. You have inferred correctly. The reason? Several, which I’ll review here. The biggest of these? There is no good evidence for the vast majority of them.
That’s right, there is little evidence linking most “measurable” aspects of the environment to human physical or behavioral traits. And on this point, it’s important to note that poorly controlled correlational studies (which make up the bulk of the commonly touted evidence for most environmental explanations) are not, by and large, evidence for environmental impact. Most of the solid evidence we do have for environmental impacts come in the forms of things that do physical damage (e.g., maiming limbs or traumatic brain injury) – a category which includes poisons; or are developmental deficits, such as malnutrition. Much of the rest of it (take your pick) is lacking.
Let me be clear: “strict” hereditarianism – that claims human traits are “all in the genes” is wrong.
Oddly, the impact of pathogens – particularly behavioral impacts such as the previously discussed gay germ hypothesis of Greg Cochran – is amongst the most solid known examples of true “environmental effects” – in this case, on a behavioral trait. The paper referenced in that post explained that pathogens may be a significant force behind variation in health and behavioral outcomes.
This paper, by Cochran & Ewald, noted that even many “physiological” outcomes, such as health, can’t reliably be pinned to environmental sources. So much for power of lifestyle!
A good bit of this was discussed by James Thompson in his post Diet is an IQ test. Contra what we’re told, we simply don’t have reliable evidence for environmental impacts on health outcomes or behavioral traits.
You may now be wondering what’s this about not thinking heredity is “all there is” after what I’ve just said. Allow me to clarify my position, and in so doing consolidate some of my recent comments on the matter.
See this comment of mine at HBD Chick’s (emphasis not in the original):
Behavior, and more broadly behavioral traits are environmentally context-dependent. This is a fine point that many, conceptually, fail to fully grasp. The reason why this is so is mainly because the socio/cultural/technological landscape of the day sets the playing field. People with different genetic predispositions have to adopt different tactics depending on what works; they receive a different set of incentives and feedback to their behavior [depending on the socio-technological landscape of the day]. Obviously, some people play the game of the day better than others. This is what sets up selective forces every society exerts. Of course, when the landscape changes, behavior can change over all, and who has the advantage changes.
The effective landscape explains how you can get rapid changes in behavioral traits all without comparable genetic change. As you say, the rise in irreligiosity, increasing acceptance of same-sex marriage, etc, are examples. This confuses many people, because they somehow assume that if you can have rapid environmental change on behavioral traits, that they can’t be so “heritable” after all (despite the fact that they all are). This stems from the misconception that heritability = degree of mutability, which is wrong. Average height for example has increased considerably in America over the past century (after decreasing for some time), and virtual no one then claims that height is “less heritable” than we thought because of this. The rise in obesity is another example. Some take the increase to signal that environment is much more important that it is let on.
Of course, these people mean “environment” in the sense of the environment that differs between people living today, where is the change over time was brought on by an environmental change that (in a fashion) affects everybody. The playing field is different. But that knowledge doesn’t necessarily guide you in how to change it, or if an effective change is even possible.
I’m not sure if that helps to clear up the issue for those confused about it, because it is admittedly a difficult concept to grasp.
This is a key fact that underlies my thinking, but doesn’t seem appreciated in the minds of many. The strongest evidence for some sort of environmental impact is broad secular changes in behavioral or physical traits that occur too fast to be the result of genetic change, i.e., evolution. This occurs because one’s genome unfolds in the environment it finds itself in. A change in the environment might alter the outcome of the genetic programming. Of course, this doesn’t mean that anything goes. We don’t open the door to any old environmental theory because of homeostasis. The genes are designed to produce a working copy of the organism despite a temperamental environment. The genetic code is built in with buffers that keep development on track. This is not exactly a perfect process (and some individuals’ buffering seems to work better than others), but it is a key phenomenon to keep in mind.
This also doesn’t mean that because this process occurs, we can necessarily isolate the aspects of the environment that brings about these secular changes. Often, we can’t. Two poignant examples (and two big ones in the “Dark Enlightenment” sphere) are marriage/mating behavior (i.e., the decline in marriage rates and rise of unwed motherhood) and the rise in obesity rates. In both cases, we don’t know for sure what the causes are, even if we think we have ideas about them. This is especially so in the case of obesity. Determining the causes with any certainty is difficult.
Going beyond the difficulty of isolating a cause of secular changes, assuming one even knew what theses causes were, knowing that changing an environment could affect people’s outcomes in principle doesn’t mean that it’s always possible to make the necessary changes in practice. This may ultimately prove to be a mistake, but I’ll leave it to readers for now to figure out why this is so.
OK, but that’s the grand-scale environment, the world of difference, so to speak. What about individual differences? What about that “nature and nurture” mantra we’re often fed by behavioral geneticists and others on the matter? Well, turns out that’s a bunch of bullshit too. See the post on the matter over at HBD Chick’s, it’s not nature and nurture…, where she quotes Steven Pinker (HBD Chick’s emphasis):
“Even the technical sense of ‘environment’ used in quantitative behavioral genetics is perversely confusing. Now, there is nothing wrong with partitioning phenotypic variance into components that correlate with genetic variation (heritability) and with variation among families (‘shared environment’). The problem comes from the so-called ‘nonshared’ or ‘unique environmental influences.’ This consists of all the variance that is attributable neither to genetic nor familiar variation. In most studies, it’s calculated as 1 – (heritability + shared environment). Practically, you can think of it as the differences between identical twins who grow up in the same home. They share their genes, parents, older and younger siblings, home, school, peers, and neighborhood. So what could make them different? Under the assumption that behavior is a product of genes plus environment, it must be something in the environment of one that is not in the environment of the other.
“But this category really should be called ‘miscellaneous/unknown,’ because it has nothing necessarily to do with any measurable aspect of the environment, such as one sibling getting the top bunk bed and the other the bottom, or a parent unpredictably favoring one child, or one sibling getting chased by a dog, coming down with a virus, or being favored by a teacher. These influences are purely conjectural, and studies looking for them have failed to find them. The alternative is that this component actually consists of the effects of chance – new mutations, quirky prenatal effects, noise in brain development, and events in life with unpredictable effects.”
Here she continues, quoting me on the matter (HBD Chick’s emphasis):
“The heritability of behavioral traits is typically on order of 50%. However, what’s left (after you subtract the ‘shared environment’, which is generally 0, but more on that soon) is just the ‘unexplained variance.’ We don’t know what that is. Much of it, perhaps a good deal, is measurement error. Evidence suggest that that is actually missed heritable influence.
“However, what’s left over, after you’ve accounted for ‘attenuated heredity’ may be what’s known developmental noise. This is ‘environmental’ in the sense that it’s not inherited, but is essentially random and not subject to controlled manipulation.
“Or we think it’s random. See Kevin Mitchell on it:”
.
“Even developmental noise appears to heritable, to a degree. Whether or not this is ‘on purpose’ or an evolutionary accident is unclear.[Edit, 9/13/14: And now we have additional evidence that this is the case. Experiments on multiple strains of genetically identical fruit flies have found that some strains are more prone to having variable trait expression despite an identical genotype than are others. The range of variation is itself influenced by the presence of certain genes. Additionally, these genes don’t seem to allow for greater variation across the board, but rather, greater phenotypic variation in specific traits. In short, the degree of variation, in the case of humans, between identical twins, may indeed be a function of the genotypes of those twins. See Ayroles, et al, 2014]
“And finally, and this is an ‘advanced’ topic, impact of the ‘unique environment’ – what makes identical twins raised together different from one another – could itself significantly genetic in nature, because identical twins aren’t actually genetically identical, but have different de novo mutations.
“You see why I’m a little hard on the ‘nurturists’ out there. Broadly, the evidence has not been kind to ‘environmental’ influences. Note that this is not to say that they don’t exist.”
About that 50-50 split, I noted that much of the 50% not ascribed to genes is in fact measurement error. Staffan had a post on that matter (emphasis added):
So, what does the “new” research from the 1980s, that is now finally beginning to reach public awareness, tell us about human nature? The most obvious part is that nature is a major factor. This is typically summed up in textbooks in the 50/50 rule, claiming that genes and environment can explain about half of the variance each of things like intelligence, personality, psychopathology etc. Which is easy to remember – but also incorrect. This is due to the fact that there is something called measurement error. Most studies are done in a way that doesn’t distinguish this error from the environmental factor. So it’s 50 percent nature and 50 percent environment plus measurement error. Studies that have managed to minimize measurement error typically yield heritabilities for personality traits and similar characteristics around 70 percent. You also have the fact that some of the traits linked to the most important life outcomes, like intelligence and impulsiveness, have even higher heritabilities, around 0.75-0.80.
Here’s a quote from the abstract of one of these studies Staffan mentioned (emphasis mine):
Our analysis of self-report data replicates earlier findings of a substantial genetic influence on the Big Five (h2= .42 to .56). We also found this influence for peer reports. Our results validate findings based solely on self-reports. However, estimates of genetic contributions to phenotypic variance were substantially higher when based on peer reports (h2= .51 to .81) or self- and peer reports (h2= .66 to .79) because these data allowed us to separate error variance from variance due to nonshared environmental influences. Correlations between self- and peer reports reflected the same genetic influences to a much higher extent than identical environmental effects.
And of course, there is one additional factor, something that’s greatly under-appreciated (because it’s inconvenient for researchers) but is likely very powerful. Quoting myself from over at HBD Chick’s (emphasis in original):
And finally, perhaps most poignant of all, but greatly underrated, is the fact that that identical twins are not actually genetically identical, but possess subtle differences due to de novo mutations. While behavioral geneticists and others like to ignore these, identical twins are our metric of the effects of heredity. We think we can precisely measure the genetic effect vs “environmental” one by looking at identical twins raised together – anything different between them must be due to environment, so the story goes. But the differences between them could be due to genes, so in reality, we have no idea how big the effect of the “environment” truly is.These differences are starting to recognized as being potentially powerful, as seen from the differences of supposedly (but not truly) genetically identical mice:
All mice are the same, until they’re not | Science News
Genetic tests that can distinguish between identical twins are becoming availible. This is an underappreciate goldmine in future research into genes and environment.
There’s a dude over at Steve Sailer’s that was trying to argue with me about this key point. He’s trying to claim that since most mutations are of neutral effect, we can ignore these subtle genetic differences between identical twins. Well, the mouse studies indicates that we can’t. Tiny genetic differences can lead to large differences in expressed traits. This has practical significance up and down the board. For one, it does cast into question the wisdom of assuming twins are perfect genetic control in observational studies (as I said to Staffan, the genetic confound never goes away).
This post is a teaser because I plan a longer, much more thorough post on the topic soon. However, I wanted to summarize what I have said on the topic so far. The key problem with recognizing the true pervasiveness of heredity and the relative insignificance and capriciousness of the environment is that it makes it all the more difficult to craft a better a world. This isn’t a problem for only the blank-slatist types. The HBD-aware often share these hopes. Many in this space leave the door open for the environment in the hopes that we can engineer better outcomes if we try (not just harder, as utopian liberals believe, but, perhaps smarter as well). From, parenting, to lifestyle, to social engineering, unfortunately, it turns out, the reality is not so simple. There isn’t always something you can do. The truth calls for a type of serenity – accepting what you cannot change. Perhaps this makes heredity an even harder sell than it is, but in all our marketing, we (or at least, some of us) have to be sure we aren’t sacrificing the truth in the process.
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Even under the assumption of no ‘environment’ effects, there is still stuff we can do. It just requires generations – quite literally – rather than years. We have a lot of information about the effect of selection pressures on people, and we need to use it.
But eugenics hasn’t been admissible into discussion since World War II. I suspect if you go back to the literature of the 1930’s, there is a fair bit of worthwhile postulation on how to achieve some of the changes we’d like to see over time.
Evolution will continue whether we want it to or not. The social incentives in place now will effect generations down the line for a long time. The question is, do we consciously attempt to control the incentive mix, or simply let the chips fall where they may. The problem with eugenics is always the same: you have to define what ‘better’ would be or ‘best’ would be and every group (even every person) out there is going to have their own idea of the model citizen.
Of course it does. However trying to address problems – in Australia for instance a life expectancy and IQ gap to the aboriginal population – without addressing the genetic issues is going to be fruitless and frustrating.
@Sisyphean:
I’ll go out on a limb and wager that most people have roughly the same idea on what type of people they’d like to have more of.
I’d be interested to find that out too. You’d think ‘Smart’ would be part of the default choices but that doesn’t seem to stop people from hating the Jews. In my (albeit limited) experience smart people seem to think smarts should be the main qualifier but smarts often come with other unsavory attitudes disliked by many such as universalism, modern left liberalism or worse… weirdness. As someone in the 99th percentile for openness to experience with relatively low conscientiousness, I’ve experienced first hand how off putting my thoughts and actions are to regular folks. I’d guess most people would agree that they’d like to see more ‘people like me’ and the people they’d like to see less of is ‘people who are different than me.’
~S
@Sisyphean:
I’d imagine attractive, smart, and physically healthy are givens, in that order. I’d go on to add that most people probably would like for there to be more well-behaved (i.e., non-criminal), at least somewhat hard-working people around. That is, people who you wouldn’t mind being your neighbors.
I’m not sure if you need to specify more than that, yet. Of course, if you did, you’d get vastly different opinions. And I’d suspect that, more or less, they would be “like me”, only with more of the aforementioned traits. Remember, don’t base your thoughts on what people want from “what people in the alt-right blogosphere want.” Liberals would want more liberals, the religious would want more religious, etc, I think. I don’t really see why would would need to somehow winnow the range of personalities (that type of diversity is good), exception of selecting against criminal or exploitative types.
I live in the Midlands of America, the ideals of the alt-right blogosphere aren’t foreign to me, I see them every day. I’d give you Health and beauty for sure, but not smarts. I’ve known too many people who regard brains beyond a certain level with suspicion and distrust. My experience tells me that regular people are far more interested in their children having the same values they do than they are that they ace the SAT. If they had to trade one for the other values would win out… but hey I could be wrong.
And bear in mind I’d not saying people are wrong to think this way either (if indeed they do). Group cohesion is important and if there’s one I’ve noticed about weirdo artists like myself it’s that we are contentious and contrarian. when you get too many of us, you don’t have a culture, you just have an atomized group of mixed nuts with no overarching direction or goals.
@intuitivereason:
This does seem to make eugenics all the more important, doesn’t it?
Yes. Makes it the only means by which some problems can be addressed.
In my experience, a significant % of Americans actively hate smart people. A much smaller % likes them.
” From, parenting, to lifestyle, to social engineering, unfortunately, it turns out, the reality is not so simple. There isn’t always something you can do. The true calls for a type of serenity – accepting what you cannot change.”
Simply accepting this on a widespread level would certainly improve the world to a certain degree. Channeling Bryan Caplan here, the belief that intelligence is environmentally modulated, leads to a way over-bias in how much schooling kids receive. Both in terms of hours a day and number of years. Much of this schooling is not of the variety of learning essential and useful skills, but a vain attempt at general intellectual stimulation or “learning how to learn.” As any parent stuck staying up all night to finish the seventh grade science project can attest, this makes being a parent a lot less enjoyable than it needs to be.
For the student the undue stress and needless sense of failure continue throughout the educational process. For example in a field like computer science dropout rates for even the basic intro courses regularly exceed 50%. Yet it’s been well known for a while now that a simple logic test administered before the course can quite accurately predict success. Yet these are widely shunned in most academic departments for association with various forms of “privilege”. Thousands of students are made to feel stupid and discouraged from higher education for no reason whatsoever.
I’d also add from a health perspective, a shift in attitude towards genetic determinism (and hence away from correlation based medicine) would be quite positive. Studies that purport to to measure long-term health affects are riddled with biases, inconsistencies and confounding variables. But short-term studies are easily subjected to the gold standard of controlled randomized experiments. The problem is the former get more attention because they come along with headline grabbing titles about dying early. Whereas the latter are more frequently about quality of life issues.
For example mountains of controlled experiments show that resistance training mitigates the effect of age-related muscle and bone loss and cognitive decline. This presents a whole slew of quality of life benefits for the elderly like greater mobility, lower fall risks, less time spent in hospital beds, less social isolation, better life engagement, etc. The evidence for this is solid, concrete, experimentally tested and largely indisputable.
But for decades the medical establishment promoted low-and-slow aerobic exercise to the almost exclusion of resistance training. In fact many doctors even explicitly advised against it. Aerobic exercise is certainly fine, and has its own documented benefits, but it absolutely should not replace resistance training. Particularly for older individuals where even a moderate volume of aerobic exercise drastically increases injury risk.
Resistance training was out of favor because of vague concerns about the long-term impact on cardiac hypertrophy and other heart problems. Findings rooted in correlation based medicines, most ultimately proven false during this century. From a health perspective orienting your lifestyle around recommendations based on short-term quality of life studies is a better strategy than relying on noisy and unreliable long-term longevity studies.
@Doug:
Well, actually this gets tricky. Randomized controlled trials (RCTs), when they do exist in medicine, tend to be short of duration with small samples (because they’re the cheapest), which are rife for the problems of publication bias (only publishing studies that show the results you want) and statistical legerdemain (not to mention the problem of plain old low statistical power). Do you know of any large trials of long duration on the topic, or perhaps any meta-analyses?
As well, studies have shown a highly variable individual response to exercise (see here from Steve Hsu on it). Even if the total average of the group showed a positive response to exercise, this may mask great differences in how each participant made out. This has a huge impact to how useful such a prescription is to the average person. Ideally I’d like to see studies that tabulate individual variability.
I’m not sure what the studies say about resistance training, but my parents’ doctors are advising certain amounts of resistance exercise for both of them. (Dad’s 83, Mom isn’t claiming to be 29 anymore.) So whether the research is actually any good, someone’s listening to it.
@Anthony:
My suspicion is that it does have value for some people. That’s why certain people become bodybuilders, for example.
In any case, I generally advise people to do what works for them. If it seems to work, just keep right on doing it.
Looking forward to the bigger post on this. Right now we need some data on exactly how much the MZ twins differ genetically. That could change things dramatically and go a long way in fighting the “half slatism” out there. Although just informing about the design and terminology of the studies should do that too.
@Staffan:
“Half slatism.” I like that!
Agreed, especially when people say: “It’s nature AND nurture” but then go on to act and think as if whichever one they prefer (typically nature) is the real driver behind the wheel anyway.
~S
“it makes it all the more difficult to craft a better a world. ”
Hmmm? I guess the question I am wondering about is, better for whom? Clearly the rich and intelligent know how to craft a better world for themselves, at least in the short run. Upper-middle class bourgeois utopias (aka the suburbs back in the first half of the 20th century) are a good example of this. But what about the rest of the population? Their may be no way to craft a better world for all of them — though I question even that conclusion — but it doesn’t follow that there is no way that some of them — self-selected subgroups — cannot craft a better world for themselves. Isn’t this what you see in various “whitopias” (sp?) scattered around the country? Granted, they are all pretty g loaded communities, so let us ask: is it inconceivable that there might be strategies to craft better worlds for average groups of people — average in terms of their normal distributions of various desirable human traits (not including sociopathy for instance) ? I think there is, but then I may be a fool. In fact, a fool I will always be!
In general, I’m skeptical of the ability of anyone on the outside to really come in and fix things for people, just because outsiders tend not to really understand why things are as they are. I like to think that most people, so long as they have the necessities of life, aren’t being over-taxed or slaughtered by war, sick or in the middle of a natural disaster, have a family/community around them, and aren’t staring at a bunch of people who’re richer than themselves, will be relatively happy. When folks come into a place and destroy the things that made good lives possible for people (fencing off grazing land, for example,) then we get misery. When people then come and try to switch people to a new lifestyle (convert hunter gatherers to pastoralists, for example,) we probably get a mis-match between skills and necessity, and that probably also causes misery. And once these things have happened and the old lifestyles aren’t viable anymore, I don’t know. But I wouldn’t assume that folks are unhappy or need help just because they’re poor.
Saw this today, and found it rather interesting: http://news.nationalpost.com/2014/03/07/the-science-taboo-there-may-be-genetic-realities-to-race-but-not-along-the-lines-we-expect/
Seems like the media is taking notice.
Why the explosion of dysfunction beginning in the late 1960s?
@fnn:
Reread the post. Then ask again.
Jayman, I have a task for you I think you might like to take up. It’s been causing me a little trouble dealing with an unusually bright critic of hereditarianism and I’m not even entirely sure that they’re wrong. To keep the story short, they’re referencing Jay Joseph’s critiques of twin studies http://m.facebook.com/l.php?u=http%3A%2F%2Fjayjoseph.net%2Fyahoo_site_admin%2Fassets%2Fdocs%2F2013_Joseph_Fallacy_of_the_Twin_Method_in_the_Social_and_Behavioral_Sciences.262140341.pdf&h=vAQHWf_xc&s=1 , http://www.futurepsychiatry.com/blog/twin-separation-studies-pro-and-con-for-biological-basis-of-psychiatric-disorders and it looks to me like if that goes, so does a significant chunk of the basis for hereditarianism, even if it doesn’t necessarily ‘prove hereditarianism wrong,’ per se. If you should decide to take the issue up, I’d appreciate if you could send some kind of something to my Facebook page to ensure I get notice of it. https://www.facebook.com/profile.php?id=100006548798446&ref=tn_tnmn
The crux of Jay Joseph’s argument is that twin studies, et al. do not adequately control for the so-called “equal environments assumption” (EEA). That is, Joseph believes that the physical similarity between identical twins might over-inflate their correlations for traits like IQ, et al., thereby yielding heritability estimates that are excessively high.
That’s a pile of bull crap — and even if we didn’t have the twin studies, we’ve got heritabilities from GWAS studies that are mostly concordant with estimates from the classical twin study design, as well as estimates from longitudinal adoption studies. There really is no reason to doubt them at this point. The game is up, and that ship has already sailed. Why waste countless man-hours dithering over rough approximations that are hardly different than they were in Cyril Burt’s day?
Leaving that aside, there are a number of studies confirming the EEA that he either flat-out ignores or dismisses in a cavalier fashion throughout the entire book. For instance: While it is true that the parents of identical twins do treat them more similarly than they treat fraternal twins (e.g. by dressing them in identical outfits, feeding them identical meals, etc.), there’s a considerable degree of variation between families in how similarly identical twins really are treated. For instance, Linda and Sue’s parents might encourage their twins to express their individuality by forcing them to play different sports, etc., while Bob and David’s parents have dressed them in identical outfits since infancy because they look so darned cute. Their peers, in turn, might amplify the any similarity in appearance between the twins (either real or perceived) by treating them accordingly. And to this date we have found no correlation between the similarity of treatment and concordance rates for things like IQ. None whatsoever. Consult citations below:
Psychol Med. 1994 Aug;24(3):579-90.
Twin Research and Hum Genet. 2006 Jun;9(3):403-411
Acta Psych. Scandinavica 2007 Apr;81(4):322-326
Here’s another test: Every once in a while, parents will produce dizygotic (fraternal) twins who are so similar in appearance that they are treated as identical twins, until medical testing proves otherwise. (To give you an example, the famous duo Mary-Kate and Ashley Olsen are fraternal, not identical twins — but you wouldn’t know this at all by looking at their childhood pictures.) In essence, they don’t turn out to have life outcomes that are any different than outcomes for fraternal twins who are dissimilar in appearance, or two ordinary siblings from the same family, for that matter. There is no relationship whatsoever between how similar dizogytic twins are in appearance and how concordant they are for psychometric traits — the correlations are exactly what you might expect from them sharing (on average) 50% of each others’ DNA, and nothing more.
See here:
Behav Genet. 1995 Jul;25(4):327-35.
Behav Genet. 1976, Volume 6, Issue 1, pp 43-52
Behav Genet. 1993 Jan;23(1):21-7.
Behav Genet. 2013 Sep;43(5):415-26
And here is a comprehensive review article that suggests that the EEA is valid in most, if not all cases, but that further testing may be needed to assess the magnitude of the discrepancy (if any exists).
Soc Sci Res. 2014 Jan;43C:184-99
In essence, Jay Joseph abhors all findings from behavior genetics because it refutes his belief that social inequities are largely responsible for everything from schizophrenia to drug abuse and more. He is a politically motivated charlatan, not a serious researcher with an abiding interest in the accuracy of scientific findings. You might as well chuck him into the same category with activist bozos like Lewontin and K. Richardson.
I suggest that you read Jacob Felson’s review article very carefully — in it, he refutes most of Jay Joseph’s most common objections, while noting that the EEA has been demonstrated to be valid for all sorts of traits ranging from educational attainment, to IQ, to eating disorders and more. (He notes that it might be slightly untrue for neuroticism, but Occam’s Razor suggests that it’s true for all of the Big 5, not just four of them.) Forget what the abstract of the paper says. Read it in its entirety.
If you have a microsoft onedrive account (I highly recommend one for sharing and uploading files — you get 7 GB for free!), feel free to download it below:
[link removed]
In summary, there really is no way that you can inflate correlations between identical twins by treating them similarly. And even if the twin studies were worthless, we’ve got multiple strains of evidence demonstrating that virtually all behavioral traits are heritable. Anybody who cites Jay Joseph’s nonsense at this point is not worth a minute of your free time.
(P.S. Jayman, could you please take down the link above after a week or so? I don’t want the wrong people accessing my profile. Thanks.)