Genetic Moderation of the Association Between Early Family Instability and Trajectories of Aggressive Behaviors from Middle Childhood to Adolescence.

The present study tested models of polygenic by environment interaction between early childhood family instability and polygenic risk for aggression predicting developmental trajectories of aggression from middle childhood to adolescence. With a longitudinal sample of 515 racially and ethnically diverse children from low-income families, primary caregivers reported on multiple components of family instability annually from child ages 2-5 years. A conservative polygenic risk score (p = 0.05) was generated based on a prior meta-genome wide association study. Trajectories of aggression were identified using a curve of factors model based on a composite of primary caregiver, alternate caregiver, and teacher reports at five ages from 7.5 to 14 years. The family instability by polygenic interaction predicted growth in children's aggression such that children with lower levels of family instability and lower polygenic risk exhibited a steeper decline in aggression from 7.5 to 14. Findings support the need to model gene-environment interplay to elucidate the role of genetics in the development of aggressive behaviors.