Does environment matter? A review of nonshared environment and eating disorders.

OBJECTIVE

Nonshared environmental influences are experiences that are unique to siblings reared in the same family. We review studies highlighting the importance of nonshared factors for the development of eating disorders and suggest areas for future research.

METHODS

Findings from behavioral genetic studies of eating disorders as well as methodological issues are reviewed.

RESULTS

Twin studies suggest that approximately 17%-46% of the variance in both anorexia nervosa (AN) and bulimia nervosa (BN) can be accounted for by nonshared environmental factors. Studies directly examining these influences are scarce, although initial data indicate that differential paternal relationships, body weight teasing, peer group experiences, and life events may account for the development of eating pathology in one sibling versus another.

DISCUSSION: Additional research is needed to identify specific nonshared environmental influences on eating disorders such as differential parental and sibling treatment, disparate peer group characteristics, and differential experience of life events such as physical and sexual abuse.