The heritability of general cognitive ability increases linearly from childhood to young adulthood.
Level 3 - non-randomized controlled study
Large-scale multicenter observational twin cohort study.
PubMed 19488046 · doi:10.1038/mp.2009.55
What was done
Researchers evaluated the heritability of general cognitive ability across development in a sample of 11,000 twin pairs across four countries, measuring heritability at age 9 (childhood), age 12 (adolescence), and age 17 (young adulthood).
What was found
Heritability of general cognitive ability increased significantly and linearly with age, from 41% at 9 years to 55% at 12 years and 66% at 17 years.
Why it matters
This finding challenges the idea that accumulated environmental exposures reduce genetic influence over time, showing instead that genetic differences account for an increasing share of variation in cognitive ability into adulthood.
Limits
The abstract does not report confidence intervals, specific cognitive testing instruments, loss to follow-up, or breakdown by country and zygosity. Twin models also rely on classical biometric assumptions such as the equal-environments assumption.
Cited by
- context The heritability of cognitive ability and intelligence test scores increases with age until approximately age 12.