The contribution of genetic and environmental influences underlying disordered eating to exposure to weight-conscious peers.

backgroundGirls with predispositions for disordered eating (DE) may select into weight-conscious peer groups (i.e. peer groups that emphasize body weight/shape). However, factors driving selection into these peer groups remain unknown, as genetic and/or environmental predisposition to DE may lead girls to select weight-conscious peers. To explore what may drive selection, the present study investigated whether genetic or shared environmental influences underlie associations between DE and exposure to weight-conscious peers and whether effects differ by pubertal status.

methodsParticipants included 833 female twins (ages 8-15) from the Michigan State University Twin Registry. Bivariate twin models were conducted to explore etiologic overlap between DE and exposure to weight-conscious peers. Separate models were run for pre-early pubertal girls and mid-late pubertal girls given past research demonstrates differences in genetic and environmental contributions underlying eating pathology by pubertal status.

resultsDuring pre-early puberty, shared and non-shared environmental correlations accounted for the overlap between DE and weight-conscious peer group exposure. Furthermore, shared environmental and non-shared environmental influences underlying DE contributed to 33.3% and 20.0% of the individual differences in weight-conscious peer group membership, respectively. In mid-late puberty, the genetic and non-shared environmental correlations accounted for the overlap between DE and weight-conscious peer group exposure. Genetic and non-shared environmental influences underlying DE contributed to 37.5% and 19.4% of the variance in weight-conscious peer group membership, respectively.

conclusionsWhile selection effects may exist across development, these effects may be driven by variance in DE due to shared environment in pre-early puberty and genes in mid-late puberty.