Age differences in genetic and environmental influences on eating attitudes and behaviors in preadolescent and adolescent female twins.

A sample of 680 11- and 602 17-year-old female twins was used to examine (a) age differences in genetic and environmental influences on disordered eating attitudes and behaviors and (b) associations between body mass index (BMI) and eating attitudes and behaviors. Univariate, biometrical model-fitting analyses indicated that 11-year-old twins exhibited less genetic and greater shared environmental influence on eating attitudes and behaviors than 17-year-old twins. Bivariate model-fitting analyses indicated that the relationship between BMI and eating attitudes was mediated primarily by common shared environmental influences in 11-year-old twins and common genetic influences in 17-year-old twins. Nonetheless, the majority of genetic influences on eating attitudes and behaviors in older twins were due to genetic effects that are independent of those operating in BMI.