How family and twin studies inform the developing nosology of eating disorders

The history of the nosology of eating disorders has been one of frequent change. These changes have occasionally been based on observation, such as the recognition of differences between “dieters” and “vomiters and purgers” (Beumont et al. 1976) or the identification of the bulimic subtype as an “ominous variant of anorexia nervosa” (Russell 1979). Other changes have been based more on opinion than on data. All modifications to the eating disorders nosological schema have not necessarily been improvements.