The intergenerational transmission of IQ

Here are some recent results, from Sandra Black, Paul Devereux, and Kjell Salvanes.

More able parents tend to have more able children. While few would
question the validity of this statement, there is little large-scale
evidence on the intergenerational transmission of IQ scores. Using a
larger and more comprehensive dataset than previous work, we are able
to estimate the intergenerational correlation in IQ scores, examining
not just average correlations but also how this relationship varies for
different subpopulations. We find that there is substantial
intergenerational transmission of IQ scores; an increase in father’s IQ
at age 18 of 10% is associated with a 3.2% increase in son’s IQ at the
same age. This relationship holds true no matter how we break the data.
This effect is much larger than our estimated elasticity of
intergenerational transmission of income of approximately .2.

Here are ungated versions, or here.  Note that a) this is based on Norwegian data, b) income elasticity declines with birth order, c) intergenerational IQ elasticities are broadly the same across different levels of education for the father, d) the sample size is much larger than usual, and e) the author caution against assuming this is entirely a genetic effect; in another study large family size lowers IQ for instance, adjusting for parental IQ.


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