Genes are overrated, genetics is underrated

Gene ExpressionBy Razib KhanMay 16, 2012 4:53 AM


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A few days ago Nathaniel Comfort pointed me to this post, Genetic determinism round-up. If you are curious go read Comfort's whole post. I honestly didn't enjoy it very much, I think I got what he was saying, but there were all sorts of circumlocutions around the overall message. But I agree one one thing in particular: an emphasis on concrete and specific genes for traits is a motif in science journalism that can be very frustrating, and often misleading. Nevertheless, that's not the only story. I believe our current culture greatly underestimates the power of genetics in shaping broader social patterns. How can these be reconciled? Do not genes and genetics go together? The resolution is a simple one: when you speak of 1,000 genes, you speak of no genes. You can't list 1,000 genes in prose, even if you know them. But using standard quantitative and behavior genetic means one can apportion variation in the population of a trait to variation in genes. 1,000 genes added together can be of great effect. The newest findings in genomics are reinforcing assertions of non-trivial heritability of many complex traits, though rendering problematic attributing that heritability to a specific set of genes. So how do we underestimate genes? Consider this story in The New York Times Magazine, Can You Call a 9-Year-Old a Psychopath?:

For the past 10 years, Waschbusch has been studying “callous-unemotional” children — those who exhibit a distinctive lack of affect, remorse or empathy — and who are considered at risk of becoming psychopaths as adults. To evaluate Michael, Waschbusch used a combination of psychological exams and teacher- and family-rating scales, including the Inventory of Callous-Unemotional Traits, the Child Psychopathy Scale and a modified version of the Antisocial Process Screening Device — all tools designed to measure the cold, predatory conduct most closely associated with adult psychopathy. (The terms “sociopath” and “psychopath” are essentially identical.) A research assistant interviewed Michael’s parents and teachers about his behavior at home and in school. When all the exams and reports were tabulated, Michael was almost two standard deviations outside the normal range for callous-unemotional behavior, which placed him on the severe end of the spectrum. Currently, there is no standard test for psychopathy in children, but a growing number of psychologists believe that psychopathy, like autism, is a distinct neurological condition — one that can be identified in children as young as 5. Crucial to this diagnosis are callous-unemotional traits, which most researchers now believe distinguish “fledgling psychopaths” from children with ordinary conduct disorder, who are also impulsive and hard to control and exhibit hostile or violent behavior. According to some studies, roughly one-third of children with severe behavioral problems — like the aggressive disobedience that Michael displays — also test above normal on callous-unemotional traits. (Narcissism and impulsivity, which are part of the adult diagnostic criteria, are difficult to apply to children, who are narcissistic and impulsive by nature.) ... The benefits of successful treatment could be enormous. Psychopaths are estimated to make up 1 percent of the population but constitute roughly 15 to 25 percent of the offenders in prison and are responsible for a disproportionate number of brutal crimes and murders. A recent estimate by the neuroscientist Kent Kiehl placed the national cost of psychopathy at $460 billion a year — roughly 10 times the cost of depression — in part because psychopaths tend to be arrested repeatedly. (The societal costs of nonviolent psychopaths may be even higher. Robert Hare, the co-author of “Snakes in Suits,” describes evidence of psychopathy among some financiers and business people; he suspects Bernie Madoff of falling into that category.) The potential for improvement is also what separates diagnosis from determinism: a reason to treat psychopathic children rather than jail them. “As the nuns used to say, ‘Get them young enough, and they can change,’ ” Dadds observes. “You have to hope that’s true. Otherwise, what are we stuck with? These monsters.” ... These differences, researchers say, are most likely genetic in origin. One study calculated the heritability of callous-unemotional traits at 80 percent. Donald Lynam, a psychologist at Purdue University who has spent two decades studying “fledgling psychopaths,” says that these differences may eventually solidify to produce the unusual mixture of intelligence and coldness that characterizes adult psychopaths. “The question’s not ‘Why do some people do bad things?’ ” Lynam told me by phone. “It’s ‘Why don’t more people do bad things?’ And the answer is because most of us have things that inhibit us. Like, we worry about hurting others, because we feel empathy. Or we worry about other people not liking us. Or we worry about getting caught. When you start to take away those inhibitors, I think that’s when you end up with psychopathy.”

I have already expressed my lack of awareness on these issues because of how much I trust the understanding of psychologists of any given endophenotype aside from IQ. But let's say they understand the trait of pscyhoopathy. And let's take the 80 percent heritability seriously. What does this mean? I've rehashed heritability and such 1,000 times on this blog, so let's go visual with few words. Imagine a scenario where a person who is 2 standard deviations above the norm in psychopathy marries someone who is 1 standard deviation above the norm (roughly, top 2% and top 15%). Assortative mating is common, so this isn't an out of the ordinary conjecture. Below are the distributions of outcomes of the offspring of these two individuals compared to the general population.

Very few people in our society think in these terms. Rather, very well educated and rich people are spending $30,000 per year on gaining the admission of their 1 year old child to a preschool for toddlers! Unless elite university admission is somehow tied in to this initial admission decision, in utero, I assume these parents are wasting their money, and I've wondered how to get some of it myself, as some people are obviously easily parted given moral panic. But their children are not getting a $30,000 "enriched" environment. Environment can only do so much. So here are two bullet points to repeat: - For behavior genes don't matter, genetics does- When you remove environmental variation, all you have left is genetic variation Internalizing this reality allows for some "quick & dirty" social science approximations.

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