(i) The heritability of intelligence increases from about 20% in infancy to perhaps 80% in later adulthood. (ii) Intelligence captures genetic effects on diverse cognitive and learning abilities, which correlate phenotypically about 0.30 on average but correlate genetically about 0.60 or higher. (iii) Assortative mating is greater for intelligence (spouse correlations ~0.40) than for other behavioural traits such as personality and psychopathology (~0.10) or physical traits such as height and weight (~0.20). Assortative mating pumps additive genetic variance into the population every generation, contributing to the high narrow heritability (additive genetic variance) of intelligence.
Pointer from Kyle Griffin. Read the whole thing. The authors’ discussion of Genome-wide Complex Trait Analysis, a new method of examining genetic influence, was new to me. Deary is the author of Intelligence: A Very Short Introduction, which doubles as an excellent introduction to statistical methods in research.
In my appearance in St. Louis in six weeks, I will be talking about the forces that cause stratification of earnings to accelerate. One of those factors is assortative mating based on g.