It is widely known and accepted that eating disorders are familial in nature. In other words, someone who has a parent or a sibling with an eating disorder is more likely to suffer one themselves. However, it is difficult to determine whether or not this is because people in families experience the same environment or because they have the same genetic predisposition to disordered eating behaviors.
Historically, many writers and therapists assumed that parents caused eating disorders. It is now known that this is simply not true. However, studies do show that family expectations and the history of parents can play a role in the creation and maintenance of disordered behaviors. For instance, girls whose fathers feel weight is extremely important are at a higher risk for binge eating behaviors. And young adolescent girls (under age 14) whose mothers have a history of an eating disorder are three times more likely than their peers to engage in purging behaviors.
Studies of twins are an important component of researching the influence of genetics on eating disorders. Research has shown that if one identical twin suffers from anorexia nervosa or bulimia nervosa, the second twin is more likely to suffer from the same eating disorder than if they were non-identical twins or non-twin siblings. Studies of twins who have been adopted would be an extremely valid way to research this further. Unfortunately, twins who have been adopted and also suffer from an eating disorder comprise such a small population that such studies have not been done.
Neuroimaging & Molecular Studies
Another way to determine the influence of biology is by studying the actual genes and parts of the brain that play a role in eating disorders. One area of these studies is focusing on the 5-HT2A serotonin receptor. Several studies have linked it to anorexia nervosa and bulimia nervosa. However, other studies have found no link. More research needs to be done in this area to determine the influence, if any, this receptor has on eating disorders.
Other studies are looking for specific areas of activity in the brain through fMRI (functional magnetic resonance imaging) studies in anorexia nervosa, bulimia nervosa and binge eating disorder. It has been found that specific areas of the brain become activated in eating disorder sufferers when presented with photographs or challenges regarding food and body image distortions. Although more research is needed, this implies that there are specific brain pathways that contribute to eating disorder behaviors.
In summary, the research does support the idea that genetics play some role in the creation of eating disorders. However, it is thought that genetics make someone predisposed to the disorder and environmental factors, such as media and cultural influences, push someone over the edge into an eating disorder.
Costin, C. (2007). The Eating Disorder Sourcebook: A Comprehensive Guide to the Causes, Treatments, and Prevention of Eating Disorders (3rd ed). New York, NY: McGraw Hill.
Field, A.E., et al. (2008). Family, peer, and media predictors of becoming eating disordered. Archives of Adolescent Medicine, 162(6). 574- 579.
Frank, G.K., Bailer, U.F., Henry, S., Wagner, A.,& Kaye, W.H. (2004). Neuroimaging studies in eating disorders. CNS Spectrums, 9(7), 539- 548.
Frank, G.K., Kaye, W.H., Meltzer, C.C., Price, J.C., Greer, P., McConaha, C., & Skovira, K. (2002). Reduced 5-HT2A receptor binding after recovery from anorexia nervosa. Biological Psychiatry, 52, 896-906.