The intelligence of heritability.

The influences of heredity and environment on behaviour are sometimes quantified as a heritability ratio, which assigns a percentage of variation in test scores to variation in the genotypes of individuals. There are compelling reasons, both biological and statistical, to doubt the validity of the common practice of partitioning variance in this manner. This paper outlines the conceptual foundations and explains the weaknesses of heritability analysis, reviews evidence of heredity-environment interaction during development, and argues for an alternative research strategy to detect and understand the functions of specific genes relevant for individual differences in behaviour.