Abstract
Direct estimates of IQ heritability based on a single family relationship such as adopted-apart relatives are often 50% greater than indirect estimates that rely on differences in correlations such as the classical twin method or nonadoptive-adoptive comparisons. Factors such as nonadditive genetic variance, assortative mating, selective placement, measurement error, age differences, and genotype-environment correlation and interaction do not obviously explain the difference between direct and indirect IQ heritability estimates. Because direct estimates are derived from separated individuals and indirect estimates are derived from individuals reared together in families, some aspect of the within-family environment seems a likely candidate but its exact nature remains to be understood.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
