Interesting I.Q. Stuff

Richard Nisbett, Intelligence and How to Get It, reviewed in the New York Times:

Nisbett bridles at the hereditarian claim that I.Q. is 75 to 85 percent heritable; the real figure, he thinks, is less than 50 percent…… if we all grew up in exactly the same environment, I.Q. differences would appear to be 100 percent genetic…… Heritability of I.Q. is higher for upper-class families than for lower-class families, because lower-class families provide a wider range of cognitive environments, from terrible to pretty good.

Over the last 30 years, the measured I.Q. difference between black and white 12-year-olds has dropped from 15 points to 9.5 points…… African-Americans have on average about 20 percent European genes, largely as a legacy of slavery. But the proportion of European genes ranges widely among individuals, from near zero to more than 80 percent. If the racial gap is mostly genetic, then blacks with more European genes ought to have higher I.Q.'s on average. In fact, they don't……

When poor children are adopted by upper-middle-class families, they show an I.Q. gain of 12 to 16 points.

Comments (4)

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  1. Tom H. says:

    Very interesting observation I had not seen before. The more similar everyone’s environment, the more important heredity will be in determining IQ differences.

  2. Bruce says:

    What about the studies of identical twins raised in different environments. Don’t they have nearly identical IQs?

  3. Stephen C. says:

    What’s amazing is that the New York Times even allows a Sunday Magazine article on this politically incorrect subject.

  4. Ken says:

    We have loads of evidence that environment matters. Just being employed by the New York Times appears to lower IQs by at least one standard deviation.