Eating disorder predisposition toward eating disorders as a result of Mendelian inheritance. Twin studies have found a slight instances of genetic variance when considering the different criterion of both anorexia nervosa and bulimia nervosa as endophenotypes contributing to the disorders as a whole. A genetic link has been found on chromosome 1 in multiple family members of an individual with anorexia nervosa. An individual who is a first degree relative of someone who has had or currently has an eating disorder is seven to twelve times more likely to have an eating disorder themselves. Twin studies also show that at least a
Eating disorder specified feeding or eating disorders. Anxiety disorders, depression, and substance abuse are common among people with eating disorders. These disorders do not include obesity. The cause of eating disorders is not clear. Both biological and environmental factors appear to play a role. Cultural idealization of thinness is believed to contribute. Eating disorders affect about 12 per cent of dancers. Those who have experienced sexual abuse are also more likely to develop eating disorders. Some disorders such as pica and rumination disorder occur more often in people with intellectual disabilities. Only one eating disorder can be diagnosed at a given time.