The Blank Slate + autism is dangerous

Diagnosed autism rates, USA

The_Blank_SlateThe Blank Slate is Steven Pinker’s most prominent book. Over the years I have been feeling that it is more and more important to read just to get a sense of how the world works, perhaps because I’m now a parent. Obviously incorrect assumptions about the nature of reality, and human nature, can lead to disastrous consequences (see: Communism). One of the major issues that one can see from the personal perspective is that the blank slate deludes us with the perception that we are more in control than we are as to how the world shakes out. In a previous post about autism and heritability I tried to calm people down, including myself. And, in earlier comments about behavior genetics and heritability I thought it was useful to emphasize that genetics is the one thing you can control, via picking your partner. Many of the outcomes that are due to environment, and they are not trivial, are just not accounted for. We know that something non-genetic has occurred, but we have no idea.

But, there’s another side of the issue, and that is the conclusion that people take from the blank slate model of human behavior, where there has to be a cause, and where it leads people as they flail about for effective choices that make them feel empowered. Recently I was having a conversation with a friend who works in child development, and she mentioned that she knew of a family where all three sons were at some point along the autism spectrum. The two older sons were on the severe end. As someone conscious of genetics it seems highly unlikely that there isn’t a biological reason for why this couple had three children who exhibit tendencies along the spectrum. But here’s the kicker: the mother did not vaccinate her youngest son. Without awareness and acceptance of a likely genetic factor in this instance she attempted to impose the simulacrum of control upon her world by removing one possible environmental causal variant, even if all the research suggests that is not at issue. It’s easy to take a step back when you are not in the specific situation, and coldly evaluate statistics. That’s obviously not going to happen in this case, but, our society’s lack of awareness of the biological parameters which shape outcomes is clear in this particular case.

The social scaffold of ideology


There are two pet peeves which I allude to on this weblog often. First, comparing geographic entities which are not in any way analogous just because both are nation-states. Lines on a map does not an equivalency make. For example, comparing the social statistics of Finland, a relatively homogeneous nation of 5.5 million to the United States, a heterogeneous nation of more than 300 million (a better comparison to Finland might be the American state of Minnesota, with about the same population and a Nordic-skewed inflection in comparison to other American states). The problems that occur when you compare the United States in aggregate to small nations are amplified when you talk about India, which is arguably much more diverse culturally (e.g., more unintelligible languages). For example, as I’ve observed many times the BIMARU states of north-central India, the “cow belt” Hindi-speaking nations which serve as the ethno-cultural core of the nation-state, are in many ways more comparable in social statistics to Pakistan than the rest of India (e.g., the status of women, social stratification, and total fertility rate). The total fertility rate in the states of Punjab, West Bengali, and Tamil Nadu, at the northwest, southern, and eastern, peripheries of India respectively, are at or lower than the total fertility rate for non-Hispanic white Americans. In contrast, the fertility in the BIMARU states is in the range as Pakistan, ~3 to 3.5 (estimates vary based on source).

Second, religious ideology can often mislead one in terms of making inferences. What usually occurs is that one observes a particular social dynamic, and one engages in abduction to a plausible hypothesis. As an illustration, a friend once posited that the reason India, Pakistan, Bangladesh, and Sri Lanka have all had female political leaders is due to the existence of the religious movements devoted to goddesses (even though Islam and Theravada Buddhism do not incorporate female supernatural entities, his thesis was that it formed a cultural substrate). This is reasonable, but there are some immediate objections. First, the female leaders who have ascended to power have done so on the coat-tails of political dynasties. They were the daughters and wives of male political leaders, and invariably drew upon that charisma. Rather than an argument in favor of tolerance for female power, it could be that in South Asia the dynastic and hereditary principle is supreme. This is in fact the pattern in the pre-modern world. Hatshepsut, Cleopatra, and Elizabeth I reigned as representatives of powerful royal families (and in these cases there were various contingencies which removed viable males from power). In addition, there are plenty of societies where the mother goddess looms large. The Japanese emperors claim descent from Amaterasu, while Guanyin is pervasive across Chinese the breadth of civilization. In Shia Islam the women in the family of Ali are very prominent, while in much of Christianity (i.e., all but the Protestants) devotion to Mary is institutionalized.*

These are all reasons why simply inferring backward toward simple and elegant hypotheses are so often failures in term of long term robustness in complex domains. Max Weber famously did not think that capitalism would flourish in East Asia because of Confucianism. During the 1980s and early 1990s Confucianism, which encouraged some level of broad education historically to increase the pipeline of candidates for the bureaucracy, was offered as a reason for why capitalism succeeded in East Asia! This is also why I usually “update” a bit as to the credibility of commenters (including longtime regulars) who explain to me in childlike terms why the Koran explains something particular about Islam (childlike because they exhibit literally childish levels of knowledge about the topic at hand). Social phenomena are complex, and often exhibit multiple interacting causal factors. This does not mean that modeling them in intractable, but it is hard. Those who offer simple elegant explanations are often not encumbered by excessive overhead of fact in their picture of the world (ironically I believe this is also the case for adherents of various anti-positivistic Post-Modernist movements).

survey-mainThe figure to the left is from an article, Biggest caste survey: One in four Indians admit to practising untouchability. First, one has to be careful about taking people at face value. Most people when surveyed also think they are above average in intelligence! In all likelihood this is an underestimate of caste prejudice. But notice that though there is a difference between Muslims and Hindus, it is a matter of factors, not order of magnitudes. This is notable because caste is fundamentally part and parcel of Hinduism at its root and bone, despite what reformist movements such as Arya Samaj might claim. In contrast, Islam, especially the Sunni Islam dominant across South Asia, is arguably the most explicitly egalitarian of the older religious traditions. Though there are some distinctions, such as that between descendants of the prophet Muhammad and everyone else, the majority of the hierarchical aspects of contemporary Islam date to later accretions due to interaction and synthesis with other cultures, rather than from the founding period.** In South Asia there were distinctions between those Muslims who were notionally descended from non-South Asians (Persians, Turks, Afghans, and Arabs***, or ashraf), and those who were descended from converts. This was rather obviously an explicitly racial distinction, between “white” and “black” Muslims in the local parlance. But among Muslims themselves converts often retained some element of caste pride and consciousness. It is almost certain that some high caste Hindus shifted to ashraf status despite being indigenous in origin. But more obviously there are Muslim groups such as the Khoja who retained their previous Hindu caste consciousness even while shifting toward a Muslim identity. In light of these historically contingent facts it is natural that many Muslims admit to practicing untouchability despite its lack of sanction within the precepts of any Islamic religious tradition. It is also practiced in Pakistan despite its aggressively non-Hindu national self-identity.

But digging deeper into the article highlights some important facts:

Spatially, untouchability is most widespread in the Hindi heartland, according to the survey. Madhya Pradesh is on top (53 per cent), followed by Himachal Pradesh (50 per cent), Chhattisgarh (48 per cent), Rajasthan and Bihar (47 per cent), Uttar Pradesh (43 per cent), and Uttarakhand (40 per cent). West Bengal appears to be the most ‘progressive’ — with only 1 per cent of respondents confirming they practised untouchability. Kerala comes next in the survey, with 2 per cent, followed by Maharashtra (4 per cent), the Northeast (7 per cent), and Andhra Pradesh (10 per cent).

Muslims in India are concentrated in the North. Though there are pockets of concentration in the South (northern Kerala and Hyderabad) and in West Bengal, the raw numerical preponderance of BIMARU means that Muslim social statistics will always be skewed by this region. Similarly, Christians tend to be in the South or the Northeast. The largest number of Christians in India live in Kerala. The low fractions of Christians admitting to practicing untouchability is probably a function of their concentration in progressive Kerala and the Northeast, where Indian culture has uneven penetration (i.e., some Tibeto-Burman tribes are fully Hindu in identity, while others were never touched by Indian culture and converted to Christianity of the Western  Protestant variety), as well as a larger than typical fraction of lower caste converts. Most Buddhists in India are either not part of Indian culture, or, relatively recent Dalit converts. So not only are there larger social-historical factors which influence the practice of caste among South Asians (including, genetics), but the problem of pooling national data may result in spurious perceptions.

This is not to say that ideology does not matter. My personal minimal experience is that some consciousness of caste does persist among the Diaspora in the West. But, caste in an Indian sense seems to be less relevant among those from Muslim or Christian backgrounds. This is not to say that prejudice has disappeared, but rather it manifests in more conventional class, sect, and ethnic lines which are intelligible in a cross-cultural context among Muslims and Christians (e.g., lighter skinned Pakistani Muslims  and Christians feel superior to darker skinned Muslims from eastern or southern portions of the subcontinent). Among Christians and Muslims caste is a not a sacral matter of ideology, but in South Asia it is simply a fact of the background of one’s social existence from time immemorial. In the West these parameters fade, and so the salience of caste is greatly reduced, and it is disappears without the foundational support. I would predict that among Sikhs the practice of caste in the West will fade more quickly than among Hindus, because Sikhs notionally reject the idea, even though though it is embedded in their customs.

* Sunni Turkey has had female political leaders, while Shia Iran has not. Protestant Northern Europe has had at least as many, if not more, political leaders than Catholic Southern Europe.

** The big distinction in the first century was between Arab tribes and the rest, to the point where some Christian Arabs were given privileges that were withheld from non-Arab converts to Islam. After 750 A.D. these distinctions collapsed as core Islamicate civilization absorbed more self-consciously Persian cultural forms and became dominated by a Turkic military ruling caste.

*** I include Arabs because they were a presence in maritime South India. But South Asian Islam is overwhelmingly Turco-Persianate in affect.

Open Thread, 11/29/2014

k8858Right before Thanksgiving I was in San Francisco for a friend’s wedding. Back when California was a sunny & exotic land I really enjoyed checking out the North Beach district of the city. Often this involved something as banal as swinging by City Lights, purchasing a book, and then reading a lot of it at a local coffee shop (usually Caffe Greco) Since I read Toby Wilkinson’s The Rise and Fall of Ancient Egypt, I was on the market for something covering Mesopotamia. So it wasn’t a surprise when I picked up Civilizations of Ancient Iraq at City Lights to pass the time between lunch and dinner.

10675530_10152523928987984_249001114248133538_nCivilizations of Ancient Iraq  is a rather thin and light-weight book. Nothing equivalent to Wilkinson’s attempt to distill dense scholarship into a form accessible to non-specialists. Rather, it almost reads like a primer for those interested in that part of the world after the late geopolitical events which the United States has gotten itself into. Nevertheless, it’s a nice refresher, since I haven’t read anything on this topic since A History of the Ancient Near East. The most interesting fact which always jumps out at me about this period and place is that the greatest geographical influence of ancient Iraq likely occurred before writing, ergo, before history. The archaeological record is clear that there were at least two relatively uniform cultures which expanded rapidly from Iraq, and pushed as far as Anatolia directly, and indirectly into Lower Egypt in at least one instance. The latter of these seems to have been centered around the great city of Uruk, the literal megalopolis of its age. With the authors of the book being somewhat archaeological in their focus they don’t probe in detail how this sort of phenomenon could have come to be, but it strikes me that one possibility is certainly that there were empire-scale polities before that of the Akkadians. We’ll never know definitively, but this is one area that a better consensus as to human nature could probably improve our sense of the prehistoric past in its broad likely outlines.

In relation to my recent op-ed in The New York Times (which at one point was the most emailed piece on the website, I have the screenshot to prove it!), Steve put up a nice link to it. I was expecting a few comments of the “Would not bang” genre, and of course they came up. Usually these are from people “butthurt” that I banned or verbally abused them. All I have to say to anonymous commenters on the internet who perceive themselves to be brilliant: you are an anonymous commenter on the internet, and I am not. Reality hurts. Sorry. The most trenchant critics of Cultural Marxist egalitarianism never reflect to consider they themselves may not be notable or worthy in all domains. The reason I’m mean to the unintelligent or uninformed commenters is that life is short and I get tired of having to filter that sort of stuff out, not that I enjoy being mean. As people who’ve met me in person can attest I enjoy being nice. But the plain fact of the matter is that some people have low memory hardware which can’t launch certain useful applications (the stupid), or, they haven’t bothered to install anything worthwhile to tackle the tasks which they have in their sights (the ignorant).

sense_of_style_book_coverFinally, I’m reading Steven Pinker’s new book, The Sense of Style: The Thinking Person’s Guide to Writing in the 21st Century. I’ve gotten a lot of advice on how I should write in the 12 years I’ve been blogging. Most of it has been influenced by The Elements of Style. I haven’t paid much of it any attention because I think I’m doing rather well in terms of gaining some level of notice for my writing despite not being a self-conscious writer all these years. And second, it always seemed weird to me that maxims spouted by Strunk & White really were somehow written in stone. So far Pinker has quickly refuted slavish adherence to The Elements of Style as being somehow meritorious, particular because Strunk & White themselves don’t adhere to their own style when making the case for it! But he’s also making it clear why a lot of the “Post-Modernist” style of prose strikes as bad on the face of it. Definitely enjoying it so far, though I don’t know if it will change how I write. But likely it will at least make me a bit more self-reflective, so I wouldn’t be surprised if I shifted things on the margin. We’ll see.

Pieces of interest for new readers….

Seeing as I might get an influx of people curious about me after reading my piece in The New York Times, I thought it might be useful to put some links to posts which are representative of my oeuvre. In the wake of the paper Comparative analysis of the domestic cat genome reveals genetic signatures underlying feline biology and domestication, I wrote up something for this blog, A Feline Genome in Full as well. It’s a bit more enriched on the “nerd quotient” than the piece in The New York Times.

principlespopulationgeneticsI have been blogging since mid 2002, and my interests range widely, though there’s a consistent central focus on evolutionary genetics (here’s my RSS, and my Twitter). If you find some of the posts here abstruse, a read of Principles of Population Genetics would clarify things a great deal. Here are a few genetics posts of interest:

1 in 200 men direct descendants of Genghis Khan
The Paradigm Is Dead, Long Live the Paradigm!
The Paternity Myth: The Rarity of Cuckoldry
Why Race as a Biological Construct Matters
One Gene to Banish One Concept
Our Ancestry as a Braided Estuary
“Missing Heritability” – Interaction Edition

Here are some non-genetics pieces:

The Islamic State Is Right About Some Things
ISIS’ Willing Executioners
A Quantitative Ecologist Looks at World History (Again)
How Turan Invented Islam
How the Swedes Became White

My newborn son was in the news this summer. We believe he’s the first healthy human baby born with his whole genome already sequenced.

Over the years, I’ve posed sets of ten questions to scholars and thinkers I value from various fields. Here are a few favorites:

My article in The New York Times is out

It’s about domestication, with a focus on the results from the recent PNAS paper. Our Cats, Ourselves:

It’s commonplace to call our cats “pets.” But anyone sharing a cat’s household can tell you that, much as we might like to choose when they eat in the morning, or when they come inside for the night, cats are only partly domesticated.

The likely ancestors of the domestic dog date from more than 30,000 years ago. But domestic cats’ forebears join us in the skeletal record only about 9,500 years ago. This difference fits our intuition about their comparative degrees of domestication: Dogs want to be “man’s best friend”; cats, not so much.

The bounds of human culture

Pioneer_plaqueWe live in a Whiggish age, and on the Left side of the cultural spectrum there is always the demand for the eternal revolution to march forward and transform our society. Three years ago The New Republic published America’s Next Great Civil Rights Struggle, about transgender individuals. In some ways this makes logical sense, as arguably transgender individuals are the next step beyond equal rights for people of homosexual orientation. I have argued before that scope of “social justice” in terms of personal liberation is becoming narrower, and narrower. Expanding the possibilities for women affected half the population. Expanding the possibilities for African Americans affected 10 percent of the population. Expanding the possibilities for gays and lesbians affected somewhere around 5 percent of the population, being generous with the numbers. Transgender individuals are an even smaller proportion of the population, and yet a great deal of cultural energy is now going into addressing their concerns. Some of them, such as basic safety and protection from violence, are common sense matters of human decency which I believe most people can support wholeheartedly. But other aspects of acknowledging the transgender experience require a re-evaluation of basic elements of language and social expectation. Not only will many Americans resist, I believe it is a quixotic enterprise, because though a small proportion of individuals express disjunction between their sex and gender, the vast majority do not. Many social norms did not emerge to impose a binary of sexuality, but reflect it.

To illustrate the problems, an NPR piece The End Of Gender?

To chronicle her adventures in gender-neutral parenting, Arwyn Daemyir writes a blog called Raising My Boychick. She describes herself as “a walking contradiction: knitting feminist fulltime parent, Wiccan science-minded woowoo massage therapist, queer-identified male-partnered monogamist, body-loving healthy-eating fat chick, unmedicated mostly-stable bipolar.”

She describes her boychick, born in March 2007, as a “male-assigned at birth — and so far apparently comfortable with that assignment, white, currently able-bodied, congenitally hypothyroid, cosleeper, former breastfed toddler, elimination communication graduate, sling baby and early walker, trial and terror, cliched light of our life, and impetus for the blog. Odds are good he will be the most privileged of persons: a middle class, able bodied, cisgender, straight, white male.”

The adjective cisgender — as opposed to transgender — describes someone who is at peace with the gender he or she was assigned at birth.

Daemyir lives in Portland, Ore. She and her straight male partner are expecting another baby in September.

For Daemyir, gender-neutral parenting is not an attempt to eliminate gender, “because the 70s’-era gender neutral parenting movement proved that’s not possible.”

The last is important. The late 1960s to early 1980s witnessed a great deal of experimentation in the counter-culture movements. In some ways the bounds of sexuality were more expansive than today, witness the sexual abuse at Horace Mann, which many admit were less shocking during that period when people were experimenting with the bounds of sexual behavior. Or, the support for pedophilia in some mainstream circles (see the arc of the expulsion of NAMBLA from association with mainstream gay rights organizations). We have plenty of empirical evidence of what doesn’t, and does, work (there was a similar period of experimentation in the early 19th century in Upstate New York, out of which came the Mormons).

Pieces which espouse the end of gender reflect a cultural mood in certain sectors, no more. The reality is that there are strong biological parameters to human cultural expression. There are differing levels of sexual egalitarianism across societies, but some sexual differentiation is obligate by dint of our biology, which expresses in concrete physical terms (pregnancy) as well as behavioral tendencies. Culture can both increase and dampen these differences, but they can not abolish them. A small number of individual are transgender in a straightforward sense. But the vast majority of humans don’t benefit from lack of acknowledgement of their biological realities. Or least the tendency to pretend as if the dominant modes of expression are just one among equal modes.

300px-Tiresias_striking_the_snakesA genuinely radical take on the idea of gender and sex would be to attack the biology directly: the Tiresias option, where individuals can choose their sex facultatively over their lifetime. That is, one could “experiment” with living a life as the opposite sex, and then also have the option of “changing back.” This model does not negate biology, but embraces it. And, I think it would be a much more genuine challenge to the two sex binary which is universal in human societies.* But I see few radicals talking about this realistically.

* I am aware of “third sexes/genders” in many cultures, but these are marginal to the two primaries.

Open Thread, 11/24/2014


Been busy.

The above are a set of images generated from 23andMe genotype data courtesy Mark Shriver. Comments? I’ll post on this at some point shortly.

Also, any thoughts on posts of note that I’ve put up over the years from long time readers? You can see some at the bottom of this page.

Finally, this link to reader survey results should work. With about ~380 respondents it looks like most of the core audience has followed me from Discover.

Putting IBD to bed


IBD plays a big part in my understanding of inheritance. I don’t mean inflammatory bowel disease. Nor do I mean isolation by distance. I’m talking identity by descent. Assuming your parents are “unrelated” then you are identical by descent with your sibling across some portion of your genome. You inherit identical segments from your parents, though due to recombination they will usually be non-identical at least across some part of the chromosome. Because of the law of segregation you should overlap 25% with your full sibling on the copy of the genes inherited from your mother and father (double that, and you get 50%). But this is an expected value. As it happens many siblings are not exactly 50% (e.g., I know of full siblings who share 40% of their genomes identical by descent from their parents). In the pre-genomic age this detail about variation was elided because usually you couldn’t precisely estimate the identity by descent. Rather, you just assume that you share 1/2 your genome with your full sibling, 1/4 with a half sibling or aunt/uncle or grandparent, 1/8 with your first cousin, and so forth.

Genomics has changed that. I can tell you for example that my son is ~20% identical by descent with one of his grandfathers. And, more surprisingly, he’s 18.9% identical by descent with one of his great-aunts! If expectation held his great-aunt should be 1/2 as related to him as his grandfather, but expectation did not hold. The figure above is from a review, Relatedness in the post-genomic era: is it still useful?:

Relatedness is a fundamental concept in genetics but is surprisingly hard to define in a rigorous yet useful way. Traditional relatedness coefficients specify expected genome sharing between individuals in pedigrees, but actual genome sharing can differ considerably from these expected values, which in any case vary according to the pedigree that happens to be available. Nowadays, we can measure genome sharing directly from genome-wide single-nucleotide polymorphism (SNP) data; however, there are many such measures in current use, and we lack good criteria for choosing among them. Here, we review SNP-based measures of relatedness and criteria for comparing them. We discuss how useful pedigree-based concepts remain today and highlight opportunities for further advances in quantitative genetics, with a focus on heritability estimation and phenotype prediction.

If you have academic access, you should read it. If you don’t, they seem to be proposing that we move beyond the confusing concept of identity by descent, and just think in terms of a coalescent framework. It does strike me that classical IBD-thinking is a historical contingency of genetics’ emergence in part in an age where pedigrees were very prevalent tools in interrogating patterns of inheritance. All for the good. But for non-geneticists I would suggest that these new methods which are able to pinpoint with fine precision patterns of genetic variation across pedigrees will allow us to explore in much more detail the nature of the heritability of many quantitative traits.

The X/(7 billion)-Men

516JD1M3N5LInteresting piece in MIT Tech Review by Antonio Regalado, The Search for Exceptional Genomes: They walk among us. Natural experiments, living ordinary lives, unaware that their genes may hold the clue to the next superdrug. As you certainly know by now a lot of the hype over the Human Genome Project turns out to have been unwarranted. But one thing about technology is that often people overestimate the short-term windfall, and underestimate the long-term consequences. Here’s the science & tech:

Ten years ago, scientists discovered that some people are naturally missing working copies of a gene known as PCSK9. The consequences of the mutation were extraordinary. These people, including a Texas fitness instructor, a woman from Zimbabwe, and a 49-year-old Frenchman, had almost no bad cholesterol in their blood. Otherwise, they were perfectly normal.

Drug companies pounced on the clue. To lower cholesterol, they would also try to block PCSK9. Now two separate drugs that disable the gene’s activity are nearing FDA approval. People taking the medications have seen their cholesterol levels plummet dramatically, sometimes by 75 percent.

Most large-scale genetic research is a search for the causes of disease, not the nature of health. But in 2008, Daniel MacArthur, a computational geneticist now at the Massachusetts General Hospital, became interested in how frequently genes are completely dysfunctional in healthy people. Along with collaborators, he scrutinized the genomes of 185 people.

MacArthur’s analysis, completed in 2012, found that each of us has, on average, one entirely defective copy of about 80 genes, and another 20 genes for which neither copy works. In other words, everyone’s genome is a little dysfunctional. (Most genes are present in matching pairs—one inherited from your mother, and one from your father.)

But here’s a fascinating personal twist. Just a heads up, I met Eric and Sonia at ASHG.
Read More

Genes are a concept and a thing

Quantitative Genetics
A new study in Psychological Science, Genome-wide scan demonstrates significant linkage for male sexual orientation, is getting breathless coverage in the press. Representative: “A genetic analysis of 409 pairs of gay brothers, including sets of twins, has provided the strongest evidence yet that gay people are born gay.” As a matter of fact I don’t think this is the strongest evidence that people are “born gay.” The study is decent, and better than what has come before, but the authors themselves in the text acknowledge issues of statistical power. These results could be right, but I doubt this is going to end up being a robust signal.* That being said, at some point in the next ten years I’m pretty sure we’ll localize the genes which carry variants which do result in a higher than typical likelihood of an individual exhibiting homosexual orientation. It’s a matter of time, not if. Behavioral genomics was way too optimistic in the interval 2000 to 2010. I suspect we’re starting to become too pessimistic in the interval 2015-2025.

Molecular Genetics

But the bigger point is that we already know homosexuality has a heritable component. We don’t need to know what genes, we just know that related individuals exhibit a propensity for the trait in direct proportion to their relatedness. Heritability is just the proportion of the variation of the trait (e.g., homosexual vs. heterosexual) within the population that can be explained by the variation of the genes in the population. Heritability of homosexuality is modest, but it is there nevertheless, so there is some biological component.** We’ve known this for a long time. A modest linkage study doesn’t really shift the need much at all. It’s asking and exploring somewhat different questions. It assumes heritability, and is looking to uncover its genetic architecture.

Mendelian Genetics
Mendelian Genetics

The problem here is that the public and the press conflate the concrete biophysical instantiation of genes with the abstract concept of the gene. The latter pre-dates the former by about 50 years. For two generations geneticists developed their field without a precise understanding of the biophysical mechanism of inheritance. But that’s because all Mendelian, and evolutionary, genetics requires is that the units of inheritance follow regular laws across the generations. Quantitative genetics, arguably a branch of applied statistics, is even less tied to the concrete unit of genetic transmission in the form of the DNA molecule.

Concrete physical locations of genes as structures in the material world are important data. In a field like biomedicine it has changed the whole game. Genomics as an enterprise wouldn’t really be possible in a practical sense without our understanding of the physical basis of inheritance in DNA. But that doesn’t make DNA necessarily a game change in understanding whether a trait is heritable or not. Rather, it adds detail and specificity to how a trait is heritable. For applied science the “how” is essential. But for basic research it is not the be all and end all.

* Two reasons that I’m skeptical. First, large effects like this often don’t pan out for behavioral traits. Second, I doubt it’s so simple as a common large effect variant because homosexuality almost certainly decreases fitness directly. For a variant to get moderately common with this sort of effect it had to have another outcome which was strongly favored.

** Note that genetics does not include all biological factors. E.g., developmental stochasticity or some early environmental perturbation in utero with lasting consequences.