Rethinking heritability

Two markedly different concepts of heritability co-exist in the social and life sciences. Behavioral genetics has popularized a highly technical, quantitative concept: heritability as the proportion of genetic variance relative to the total phenotypic variance of a trait in a population. At the same time, a more common biological notion simply refers to the transmission of phenotypic traits across generations via the transmission of genes. It is argued here that the behavioral-genetic concept is of little use overall, while the common biological concept is overly narrow and implies a false view of the significance of genes in development. By appropriately expanding heritability into a general causal concept based on its role in evolution, we will arrive at a new view of development, heritability, and evolution that recognizes the importance of non-genetic inheritance and the causal parity of all determinants of phenotypic traits.