Integrating the family stress model within a longitudinal sibling-adoption study of adolescent externalizing behavior.

Using a sample of linked adopted children, adoptive and birth parents (N = 561), and biological siblings residing in the birth parent home (N = 191), we examined the role of genetics within family stress processes. We tested parental hostility (7 years) as a mediator of the associations between socioeconomic strain and rearing parent psychopathology (4 years) and adolescent externalizing behaviors (11 years) in adoptive and biological parent homes. Next, we examined parent social support (4 years) as a moderator of paths from socioeconomic strain and parent psychopathology to parental hostility. Parental hostility significantly mediated effects of socioeconomic strain and parent psychopathology on adolescent externalizing behaviors in biological and adoptive parent homes, respectively. Equivalence testing of the paths to adolescent externalizing behaviors across family types indicated a negligible role of passive gene-environment correlation. Parent social support significantly attenuated the effect of parent psychopathology on parental hostility in biological families. Birth parent externalizing behaviors were not significantly associated with adoptee externalizing behaviors nor adoptive parent hostility, suggesting negligible heritable risk or evocative gene-environment processes. Full- and half-sibling correlations indicated that children's unique rearing contexts contributed to the parenting they received and the externalizing behavior they exhibited. Implications for intervention are discussed.