Is Behavioral Genetics a Null Field?

 On a whim, I signed up to present a poster at the The American Society of Human Genetics (ASHG) conference in DC. That, of course, required an actual article, so I wrote this up. It should be an easy read. It is written for a wider audience:

The Question That Must Be Asked: Is Behavioral Genetics a Null Field?

Within-Family now Fading

Within-Family PGS was said to prove definitive causal SNP’s and even though they generally give 1 or 2% of the variance explained, this was being held onto as proof of something, as Harden stated in her book, The Genetic Lottery,   “... the heritability of educational attainment is still not zero.”  Now that is (not surprisingly) being called into question with this simulation study:

A model for co-occurrent assortative mating and vertical cultural transmission and its impact on measures of genetic associations.

The study notes that GWAS are still beset by confounding, noting:

“Furthermore, we show that such inflation remains even when applying within-family based estimates.”

For the past 3 decades, behavioral genetic studies have relied on the fact that their assertions take a few years to be disproven and, by the time that happens, they have new assertions - rinse and repeat. 

 

Review of “Innate,” by Kevin Mitchell

“Innate,” by the neurogeneticist Kevin Mitchell, explores the case for a genetic and neurodevelopmental origin of individual differences in intelligence and other human character traits. As the title suggests, the book generally leans toward “nature” in the nature vs. nurture debate, and makes the assumption that “innate” implies a genetic origin, although with a more dynamic view of the path from gene to trait than one sees in Robert Plomin’s “Blueprint” or Katherine Paige Harden’s “Genetic Lottery” (links to my reviews of those books at the end of this review).

The question of the nature of individuals and how that nature arises has existed, in one form or another, for as long as human civilization, but took a specific turn in our own with the work of Charles Darwin or, more specifically, the work of his second cousin, Francis Galton, the eugenicist and polymath who applied Darwin’s evolutionary theories to human behavior and intelligence and actually coined the term “nature versus nurture.” 

Galton’s eugenic ideas have inspired quite a bit of misery and Mitchell rightly condemns these ideas. Nonetheless, he is often complimentary of Galton’s statistical  work related to trait heritability, which I find unfortunate. I don’t think one can simplistically separate this from Galton’s eugenic ideas, which were arguably the driving force behind his math, and which is still embraced by race-oriented “scientists” to this day. 

Pigeon-holing behavioral traits into mathematical boxes, so that traits like intelligence, extroversion and schizophrenia can be assessed in the same way we might assess traits like height, eye color, or other obvious physical features, or even milk production in cows is bizarre on its face and involves some unimaginative assumptions about the nature and complexity of human beings, while also ignoring ongoing philosophical debates and simplifies individual human nature down to an assumption that it must be related to differences in genetics and neurodevelopment. 

Mitchell uses the analogy of a robot being programmed, to explain his view of the mind, with  “computational algorithms of decision-making,” and  “neuromodulator circuits …tuned - they work differently in each of us, thus influencing the habitual behavior strategies we each tend to develop.”   Mitchell suggests that “brain circuits” develop with some variation in individuals that make “major contributions to our psychological traits.” None of this is demonstrable, and is the kind of theoretical understanding of the brain-as-computer you find in his field. Unfortunately, Mitchell largely sells it as a factual representation of the human mind, rather than his theoretical viewpoint, a recurring theme in this book.  I think he could use far more qualifiers when presenting his ideas.

“Geneticism”: The Making of a New ism

I cringed a bit when I first saw this paper:

Nurtured Genetics: Prenatal Testing and the Anchoring of Genetic Expectancies

Any time there is mention of applying polygenic scores, particularly for so-called “educational attainment,” it raises my concern. However, I think this paper makes an excellent point that I’d like to explore further, about the perception of a “magical” genetics, fostered by decades of dubious claims purporting to demonstrate a role for genes for traits such as intelligence, personality, and mental disorders. I, of course, challenge any such role and chalk most of the ever-changing genetic correlations noted in studies to population stratification related to class, race, geography and other such divisions of people. Even if I am completely correct about this, however, there is an unfortunate reality created by these continued pronouncements of a genetic basis for something like educational attainment, noted in the paper:

1. Primacy Effect: Presenting polygenic scores for traits, as the first units of information about a child, will lead parents to assign undue weight to that genetic information.
2. Anchoring and Adjustment Heuristic: Parents informed about a future child's genetic predispositions (before birth) will form "genetic expect-ancies" (i.e., expectations created on the basis of polygenic scores), and will be less amenable to updating those expectancies based on subsequent environmental information compared to those informed post-birth).
   
3. Nurtured Genetics Effect: Parents will search to confirm or disconfirm their genetic expectancies and in doing so, they will be exposing their child to environments conducive to the actualization of their genetic expectancies.

Even if these polygenic scores are meaningless related to educational attainment (and, they are), they will still matter for educational attainment, because they will change the perception for individuals. This is not just for parents, but for the individual, who is now born with an expectation. If you don’t think you have the genes for getting a high level education, because you have been told this, then you are less likely to pursue higher education. If you don’t have the genes for “musical ability,” you might be less likely to pursue music, etc. So in, say, one or two generations, if these polygenic scores were widely used, you might essentially make the polygenic score valid, as people pursue what they are told by these scores to pursue and their parents guide them in that direction. 

I’ve pointed this out in the past related to psychiatric diagnoses, where it is often noted that a family history of a particular mental disorder will increase the likelihood that you will be diagnosed with that disorder. Well, sure, since psychiatrists are trained to give weight to family history when making a diagnosis, you would be more likely to get a particular diagnosis if your parent or sibling has that diagnosis than a person with the same symptoms who does not have a such a family history. So if you read that “studies show” that those with a family history of bipolar disorder are more likely to be diagnosed with bipolar disorder, it might take on a different meaning with this in mind.

Another concern would be if polygenic scores are accepted on an institutional level, where they are used to make decisions affecting the future of individuals. If this sounds like science fiction, Robert Plomin, a well known behavioral geneticist stated explicitly in his book, “Blueprint,” that, in the future, elite school selection should be based in part on “inherited DNA differences.” If such were the case, it would be a matter of time before people would take into consideration what DNA their potential spouse has and the likelihood that their children would have a high polygenic score for educational attainment.

In such a scenario, polygenic scores would reinforce classist and racist social structures, keeping those already more likely to get the benefit of a higher education locked in by their genetics, even if the genetic variants used to create a polygenic score have absolutely no real effect on a person’s ability to traverse higher education! This could create an extension of classism and racism, that one might call “geneticism,” that will be its own prejudice and compound other prejudices. Clearly, there is an incentive for those in a more privileged class to use polygenic scores to effectively help reinforce an aristocratic hierarchy and this is another example of the dangers of using polygenic scores for decisions relating to the future of individuals.

Study Shows That Genetically Identical Fish Can Have Lasting Behavioral Differences.

 This is an interesting study:

The Emergence and Development of Behavioral Individuality in Clonal Fish

 The study monitored the “behavior” of a specific clonal strain of a species of fish (Poecilia Formosa). They noted that, despite the fish all being genetically identical, they exhibited varying behavior (swimming speed, how active, etc.). 

Our findings show that substantial behavioral individuality is already present at the very first day of life after birth among genetically identical individuals, suggesting that pre-birth processes like pre-birth developmental stochasticity and/or maternal effects might play considerably more important roles in shaping behavioral individuality than commonly thought.

This variability only strengthened as the fish got older. From my perspective, the interesting thing is the extent to which this suggests behavior is not that defined by genetics, at least in fish. One might assume that this would extend to the more complex behaviors of humans, though, which begs the question as to how much influence genetic variants can have in human behavior for even one generation, much less be identified in genetically different individuals who merely share some common genetic variants. The math just doesn’t seem to be there for high heritability, if there is any heritability at all.

It would be interesting to see this experiment repeated with genetically varied fish and see if there is any more variation in their behavior (assuming they are physically the same size and shape, etc.) than you see with genetically identical fish. My guess is that it would be minimal. 

Within Family Studies not Finding What They are Claiming

 More evidence that genome wide association studies (GWAS) find nothing but pop strat and noise. This study debunks the idea that you can look exclusively at family members to assess differences in genetic variation and definitively validate genetic correlations:

Interpreting population and family-based genome-wide association studies in the presence of confounding

The idea is that, since we are looking at family members (brothers, parent/sibling, etc.) and determining whether the relatives with a particular trait have higher polygenic scores (have more of the genetic variants correlated to a trait) versus those who do not have the trait, that will demonstrate that these genetic variations contribute to the person having the trait. 

One recent example is the so-called “Educational Attainment” GWAS. Before doing a within family analysis, they claimed that they found genetic variants that explained 13% of the genetic variance. When they did a within family analysis, this figure dropped down to 2 to 3% (the study does not provide an actual figure and the authors did not provide one at my request. This is an estimate I received from an expert in the field). Rather than focusing on the fact that the 13%  figure was demonstrably bloated, they pivoted to claiming that the 2 to 3% figure proved there was at least “some” genetic contribution to educational attainment. I think that this study suggests, though, that even this small percentage is possibly little more than pop strat and noise. 

After years of these studies, they have nothing at all to show for it. They nonetheless write books and advance careers making these spurious claims. The idea that “educational attainment” is genetic is harmful. It is irresponsible to continue making these claims and it is time to address the likelihood that “behavioral” traits do not have a significant genetic component.