Indirect Genetic Effects on Psychosocial Development and the Potential Role of Genetic Nurture

Environmentally mediated parental influences can inflate estimates of genetic effects by producing indirect genetic effects: associations between relatives’ genotypes, often parents’, and an individual's phenotype after accounting for the individual's genotype. Renewed efforts to study indirect genetic effects involved showing that parental alleles not inherited by the child (non-transmitted alleles) still predict offspring outcomes, a pattern sometimes labeled genetic nurture. In this review, we describe several alternative mechanisms that may give rise to indirect genetic effects: sibling effects, assortative mating, dynastic processes, and population stratification. We synthesize how extended twin and family models, parent–offspring trio designs, sibling comparisons, and adoption studies can detect indirect genetic effects. We then summarize research on indirect genetic effects across developmental domains, highlighting robust indirect genetic effects for education and limited or context-dependent effects on psychopathology and personality. We outline priorities for future multigenerational designs that clarify the sociocultural transmission of psychosocial development within families.