GENETIC QUESTIONS FOR ENVIRONMENTAL-STUDIES - DIFFERENTIAL PARENTING AND PSYCHOPATHOLOGY IN ADOLESCENCE

Background: Recent genetic evidence suggests that the most important e nvironmental influences on normal and pathologic development are those that are not shared by siblings in the same family. We sought to dete rmine the relationship between differences in parenting styles and dep ressive symptoms and antisocial behavior in adolescence, and to compar e the influence of these nonshared experiences with genetic influences . Methods: We studied 708 families with at least two same-sexed adoles cent siblings who were monozygotic twins (93 families), dizygotic twin s (99 families), ordinary siblings (95 families), full siblings in ste p families (181 families), half siblings in step families (110 familie s), and genetically unrelated siblings in step families (130 families) . Data on parenting style were collected by questionnaire and by video recording of interaction between parents and children. Results: Almos t 60% of variance in adolescent antisocial behavior and 37% of varianc e in depressive symptoms could be accounted for by conflictual and neg ative parental behavior directed specifically at the adolescent. In co ntrast, when a parent directed harsh, aggressive, explosive, and incon sistent parenting toward the sibling, we found less psychopathologic o utcome in the adolescent. Conclusions: Parenting behavior directed spe cifically at each child in the family is a major correlate of symptoms in adolescents. Furthermore, harsh parental behavior directed at a si bling may have protective effects for adolescents, a phenomenon we can the ''sibling barricade.''