Family, Pop Culture, and the Nurture Assumption

The central message of behavioral genetics is that modern human beings systematically overestimate the effects of upbringing and systematically underestimate the effects of heredity.  Judith Harris famously called this bias “the nurture assumption.”  But why are people so predisposed to the nurture assumption?

I’ve previously argued that first-hand parenting experience is misleading, because the short-run effects of parenting far exceed the long-run effects.  Changing kids is easy; the hard thing is preventing them from changing back!  I also suspect Social Desirability Bias plays a major role: “You can do anything if you try!” sure sounds better than “It’s in the genes.”

But here’s a totally different explanation for popular misconceptions about nature and nurture.  Throughout most of human history, if you knew someone, you usually knew his family as well.  When you grow up in a village, you make friends; and once you make friends, you regularly interact with their relatives.

In the modern world, in contrast, we are much less likely to meet the family.  You almost never meet your co-workers’ families.  And you often barely know the families of your close friends.  Perhaps strangely, most of the families that we “know” well are the fictional families of popular culture.  The Pritchetts.  The Bluths.  The Whites.  The Sopranos.  I’ve spent more time with the Simpson family than every family besides the Caplan family.

So what?  Well, with rare exceptions, the actors who comprise t.v. families aren’t even remotely related.  Do your ancestors come from the same continent?  Then by t.v. logic, you could be brothers – and we’re conditioned not to find the fictional relationships ridiculous.  Furthermore, since drama rests heavily on conflict and contrast, every family member gets a distinctive personality and social niche.  What t.v. family has three studious kids – or three class clowns?  Even a show like Shameless blends full-blown degenerates with nice people to handle damage control.

The result: We have little first-hand familiarity with actual biological families.  But popular culture fosters that illusion that we do.  Most of the biological families that we “know” are in fact adopted all the way down.  The main exception being kids’ roles where two twins play the same role to ease compliance with child labor laws!

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