Overestimates of the Genetic Contribution to Eating Disorders

The purpose of this article is to analyze and critique repeated claims in the literature that there is a substantial genetic contribution to eating disorders. Data from the existing twin and family studies of eating disorders were tabulated and compared to heritability estimates resulting from complex statistical analyses of the same data. Overall, concordance in monozygotic twins is 26% for bulimia and 35% for anorexia nervosa. Among the relatives of probands with bulimia, 95.1% do not have bulimia, whereas among the relatives of probands with anorexia nervosa, 97.1% do not have the disorder. The raw data refute claims that the genetic heritability of eating disorders is as high as 80%. The erroneous conclusion that there is a substantial genetic contribution to eating disorders needs to be corrected by focusing on the raw data for twin concordance and prevalence in first-degree relatives.