In this Social Science Bites podcast, interviewer David Edmonds asks psychologist Kathryn Paige Harden what she could divine about his educational achievements if all she knew about him was his complete genome. “Based just on your genetic information,” she starts, “I would be able to guess about as well as I would be able to guess if I knew how much money your parents had made per year when you were growing up.”
Based on current knowledge drawn from recent samples in the United States, Harden estimates an “educational attainment polygenetic score” accounts for 15 to 17 percent of the variance in educational attainment, which is defined by years of formal education. The strength of the relationship is similar to environmental factors such as that for family wealth and educational attainment, or between educational attainment and wages.
Harden’s “guess” is as about as educated as someone in the realm could make – she directs the Developmental Behavior Genetics Lab and co-directs the Texas Twin Project at the University of Texas. Her first book was 2021’s The Genetic Lottery: Why DNA Matters for Social Equality.
One thing she stresses is that genetic influence on human behavior is not the single-factor ideal youngsters learn about in their first brush with Gregor Mendel and his pea plants.
“Almost nothing we study as psychologists is monogenetic, influenced by one gene. It’s all polygenetic, meaning that there are thousands of genetic variants, each of which has a tiny probabilistic effect. If you add up all of that information, all of that genetic difference, it ends up making a difference for people’s likelihood of developing schizophrenia or doing better on intelligence test scores or having an autism spectrum disorder – but none of these things are influenced by just one gene.”
Plus, that “polygenetic score” varies based on environmental factors, such as whether you were raised in an authoritarian state. “If I had my exact DNA that I have now,” she details, “but I was raised in 1850s France compared to 1980s America, my educational output would be different, obviously, because my gender would have been interacting with those opportunity structures in a different way.”
As those structures evolve into ladders instead of roadblocks, the more utility we can derive from knowing the role of genetics.
“The more we ‘level the playing field,’ the more that people have environments that are rich and conducive to their individual flourishing, the more we should expect to see, and the more in empirical practice we do see, the role of genetic differences in people.”
In the shadow of eugenics and other genetics-based pseudo-sciences legacy, is harnessing that genetic influence for policy use good or bad? As Harden has experienced since her book published, “you can’t really talk about genes and education without fairly quickly running into some contested issues about fairness and equality.”
In fact, she argues that much of her on heritability doesn’t so much answer social science questions as much as it “poses a problem for the social sciences.”
In the podcast Harden discusses the Genome-wide Association Study, which she describes with a laugh as “a giant fishing expedition” in which researchers measure the DNA – genotype – from thousands or even millions of individuals and then measure that across the genome, for what comes down to “ a giant correlational exercise. Which genes are more common in people who are high on a trait versus low on a trait, or who have a disease versus don’t have a disease?”
Harden also addresses the reasons she studies identical twins in her research, the cooption of genetic tropes to advance toxic worldviews, and how race – which she rejects as a proxy for genetic differences — plays out in the real world as opposed to the lab.