Matthew Yglesias Falls into a Trap...
Matthew Yglesias writes:
Matthew Yglesias: Horatio Alger's IQ: One thing that always occurs to me when these race/IQ blowups occur is that this issue is kind of in the neighborhood of a different point that doesn't merely recapitulate the race science of yore, does seem to me to have real policy implications, and is really well-supported by the data. This is the fact that IQ test results are meaningfully predictive of various indicators of success in the United States and the main factors that influence how people score on these tests all happen in childhood or earlier (in the fetal environment, in the genes, etc.).
This then becomes one of several available lines of argument that the image of the United States as a magical place where hard work always pays off and the rewards go to those willing to put in the effort is wrong. What's more, the imagine of the United States as a fallen version of that magical place — a country that could become magical if we just improved urban high schools or adopted a better student loan system — is also wrong. Better high schools and better student loan systems are things worth doing on their own terms, but absolutely nothing one can do changes the fact that where people end up is substantially out of their hands...
This seems to me to be substantially wrong. The inheritance of inequality is strikingly large in America today: if the father's lifetime was 100% above the American average for his day, the son's lifetime income will on average be 65% above the American average for his day. That's a lot of inherited inequality. Is this unequal distribution of wealth, income, and status in the United States today the result of the fact that a genetic elite has risen to the top in an IQ-driven meritocracy?
No.
This high degree of inherited inequality isn't because high IQ genetic eliteness genes are being passed down from fathers to sons. As Samuel Bowles and Herbert Gintis (2002), "The Inheritance of Inequality," report:
The direct effect of IQ on earnings... presented in Bowles, Gintis, and Osborne (2002a)... is 0.15, indicating that a [one] standard deviation change in the cognitive score, holding constant... remaining variables... changes... earnings by about one-seventh of a standard deviation.... An estimate of the causal impact of childhood IQ on years of schooling... is 0.53 (Winship and Korenman 1999). A rough estimate of the direct and indirect effect of IQ on earnings... is then... 0.15+(0.53)(0.22) = 0.266....
h is the heritability of IQ.... The value cannot be higher than 1, and most recent estimates are substantially lower, possibly more like a half or less.... [C]ouples tend to be more similar in IQ than would occur by random mate choice.... [The] genetic correlation of parent and offspring [is] (1 + m)/2....
Using the values estimated above, we see that the contribution of genetic inheritance of IQ to the intergenerational transmission of income is (h2(1+m)/2)(0.266)2 = .035(1 + m)h2. If the heritability of IQ were 0.5 and the degree of assortation, m, were 0.2 (both reasonable, if only ball park estimates) and the genetic inheritance of IQ were the only mechanism accounting for intergenerational income transmission, then the intergenerational correlation [of lifetime income] would be 0.01, or roughly two percent the observed intergenerational correlation [of lifetime income between parents and children]...
If inherited genetically-based IQ were the source of the extra edge that the children of the rich get in our society, than we would expect a parent with 4 times average lifetime full-time earnings--say $200,000 a year--to have a kid with a lifetime average income of $51,500 instead of the average of $50,000. But it is not $51,500. It is $150,000.
I agree with Matt that "where people end up [in our society] is substantially out of their hands" (although not by any means completely): luck and inheritance of many kinds of things are incredibly important. But this does not mean that equality of opportunity is a mirage. For most of the things that are out of the hands of the individual are not out of our collective hands at all. Genetic influence on IQ is one of the big things that are out of our collective hands--and it turns out it is really not that big a thing at all.
