« Cholesterol and Schizophrenia | Gene Expression Front Page | Social mobility and IQ »
September 20, 2004

Mom & dad off the pedestal

The Nurture Assumption is a good read. Most of you know the general thesis: most of the "environmental" input that shapes your personality is not from your parents but from your peers (to make it short and sweet). I wasn't convinced by all the arguments, but it definitely makes you reconsider your background assumptions. As one reader noted it would have been ideal if Harris framed her thesis in the context of the EEA, but you can't have everything, and though she doesn't do a thorough job in explaining the ultimate origin of the behaviors she describes, I think her characterization of the proximate phenomena in under 400 pages is admirable (the confused results coming out of genetics that point to a more "unorthodox" norm for family life in the EEA might be an important factor in why peers rather than parents were paramount).

In any case, I want to give a specific example, from a section where Harris basically asserts divorce itself does not affect children very negatively (she is making a claim that the effects we see are correlations rather than causally connected):


...The divorce rate was 19 percent among the twins whose parents had remained married. Among those whose parents were divorced, the chances of getting divorced were considerably higher: 29 percent. The chances were just as high-30 percent-for those with a divorced fraternal twin, and they were higher still-45 percent-for those with a divorced identical twin...about half of the variation in the risk of divorce could be attributed to genetic influences-to genes shared with twins or parents. The other half was due to environmental causes. But none of the variation could be blamed on the home the twins grew up in. Any similarities in their marital histories could be fully accounted for by the genes they share. Their shared experiences-experienced at the same age, since they were twins-of parental harmony or conflict, of parent togetherness or apartness, had no detectable effect.

Heredity, not their experiences in their childhood home, is what makes the children of divorce more likely to fail in their own marrige....


I know this sounds kind of bizarre on first blush, it doesn't seem to jive with our intuition, but reality and intuition don't always converge. All I offer are the immortal words: read the whole thing. It is crucial to note that American public policy prescriptions from the Right to the Left are undergirded by "the nurture assumption," the importance of parents. Harris wrote before studies like the correlation between MAOA and propensity to become abusers in reaction to abuse came out, but some of her assertions about immunity of some children from negative input and the tendency of others to be easily led astray are rather prophetic when viewed in this light.

Here is another tidbit from Harris' book:


The researchers focused on children who were considered to "high risk" on the basis of their family income (low), family composition (no father in the home), and race (African American). They found that children with these risk factors who lived in mostly black, lower-class neighborhoods were highly aggressive, but those who lived in mostly white, middle-class neighborhoods were "comparable in their level of aggression" to their middle-class peers. The researchers concluded that the middle-class neighborhoods "operated as a protective factor for reducing aggression among children from high-risk families."

I'm not saying I agree with everything in Harris' book, I don't, there are plenty of nitpicks I could make. But, she offers a whole different tack. If you don't want to buy the book, it is probably in your local library, and Amazon's search function is very handy. The unfortunate thing is that I suspect it will take at least a generation for a Harris' ideas to percolate down to the popular level. Until then, you're screwed up because of your parents....

Related: Jason Malloy's excellent review of the dispute between Judith Rich Harris & Jerome Kagan. Explore her website if you are curious.

Alex's comment:
For a free précis of her book, you can read her infamous Psych. Review article online here.

Posted by razib at 11:04 PM