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Explore how assortative mating for g impacts genetic variance and the heritability of g in behavioral traits.

Written byRazib Khan
| 1 min read
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I saw this link posted on twitter, IQ and Human Intelligence:

An interesting finding from genetic research, which Mackintosh mentions, only in passing, as posing a problem in the estimation of the heritability of g, is that there is greater assortative mating for g than for any other behavioral trait; that is, spouse correlations are only ∼.1 for personality and only ∼.2 for height or weight, but the correlation for assortative mating for g is ∼.4. In addition to indicating that people are able to make judgments about g in real life, this finding suggests that assortative mating may contribute to the substantial additive genetic variance for g, because positive assortative mating for a character can increase its additive genetic variance.

I've seen these sort of results before. The review is from 1999. In general I always wonder if quantitative values for personality are not to be trusted because of issues with the measurement of personality types. But this is clearly not an issue with height or weight. And in the case of height the overwhelming causal explanation for variation in the West is genetic variation. Overall I'm rather surprised by the rather low correlations for some of these traits, such as height and intelligence. I wonder if beauty, perhaps measured by an index of facial symmetry, might exhibit higher correlation values?

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