In the genetics of the beholder: gene-environment interplay for internalising and externalising symptoms using polygenic scores and adolescent perceptions of parenting

Adolescent internalising and externalising symptoms arise from a complex interplay of genetic and environmental factors. Family processes (e.g., parenting) are thought to play a key role and may, in part, reflect parental genotype. Understanding how parents’ genes affect risk for psychopathology in offspring—whether through direct genetic transmission or environmentally mediated genetic nurture—is crucial for identifying causal mechanisms and intervention targets. We examined both genetic transmission and genetic nurture pathways of polygenic risk for psychopathology on adolescent internalising and externalising symptoms.The sample comprised 762 genotyped parent-offspring trios from the TRacking Adolescents’ Individual Lives Survey (TRAILS). Parent and offspring polygenic scores (PGS) for genetic liability to general psychopathology (p-PGS) were computed and jointly modelled to estimate genetically transmitted and genetic nurture contributions to parental reports of offspring internalising and externalising symptoms at age 11. Results indicated that parental p-PGS influenced offspring symptoms primarily through environmental, rather than direct genetic, pathways. Specifically, we found evidence for genetic nurture, such that parental p-PGS was associated with adolescent internalising (but not externalising) symptoms, over and above the effect of adolescents’ own p-PGS. However, we found no association between parental p-PGS and adolescent-reported parenting behaviours, limiting our ability to assess whether genetic nurture effects were mediated by adolescent perspectives of parenting. The study highlights the need to consider reporter effects in genetic nurture studies, encouraging the use of multiple reporters and inclusion of both parents, as here. More comprehensive proximal and distal environmental measures would also be helpful.