The importance of nurture versus nature is an always fun discussion topic for sophomore dorm rooms. My impression is that it is no longer a question of much scientific interest, as it’s long been clear that environment and genetic endowment interact. You just can’t separate the effect of inherited characteristics from the effect of social environment. Owen Thompson offers us Economic Background and Educational Attainment The Role of Gene-Environment Interactions,” to provide a cute piece of evidence on genetic endowment, environmental interactions, and educational outcomes.
Roughly half of people have a particular version of a gene called “monoamine-oxidase A.” The version of the gene you have affects neurotransmitter activity. Owen shows that if you come from a below median income household, having the A variant of the gene makes a big difference in educational outcomes. 35 percent of men with this variant graduate college versus only 25 percent who don’t have the variant–among the below average income group. Men drawn from the above-median income group? An identical 52 percent graduate college whether they have the gene variant or not.
Results for high school graduation point in the same direction. Family income matters if you don’t have the MAO-A variant but not if you do. In other words, how your genetic endowment expresses itself very much depends on environmental factors.
And I have to copy in a quote Thompson included in his paper ’cause it’s just so clever.
Flamingos everywhere are famous for their beautiful pink color. [But] if flamingos do not have access to their usual diet [of shrimp and plankton] for any reason, they are white, not pink. Their color is entirely dependent on the environmental influence of diet. On the other hand, the flamingo’s ability to turn pink with diet is entirely dependent on their genes. You could feed seagulls forever on the same diet and they would never turn pink. It would make no sense to say the flamingos’ color was 50 percent due to genes and 50 percent due to diet. The color is due to the joint action of genes and environment.” (Rutter 2006)