Importance of nonshared environmental factors for childhood and adolescent psychopathology.

OBJECTIVE: To briefly summarize behavioral genetic findings in relation to child and adolescent psychopathology, paying special attention to the environmental rather than genetic components of variation, and to describe recent research exploring specific nonshared environmental processes in the development of adolescent depression.
METHOD: Behavioral genetic studies of child and adolescent psychopathology were outlined, with special attention given to findings from the Nonshared Environment and Adolescent Development Project. This project was also used to explore maternal negativity as a "candidate" nonshared environmental influence for adolescent depression.
RESULTS: These studies indicate that the environmental factors influencing developmental psychopathology are primarily of the nonshared variety (with the notable exception of juvenile delinquency). In addition, consistent results have not yet emerged from assessments of adolescent depression. Finally, maternal negativity was identified as a specific nonshared environmental factor related to adolescent depression.
CONCLUSIONS: The environment as well as genetics is important to understanding childhood psychiatric disorders, and behavioral genetic designs provide the best evidence for this. Specifically, environments not shared by siblings are particularly salient. From a clinical standpoint, these considerations point to the importance of assessing the entire family rather than only the family member with the "problem."