Genes or Environment: What Causes Eating Disorders?

Two young girls pose for each otherResearch has determined that eating disorders are caused by a confluence of factors. No one single factor is enough to cause someone to develop an eating disorder, but certain factors set the stage for a person to be vulnerable to developing an eating disorder. When it comes to eating disorders, the age-old question of nature versus nurture is answered simply: it’s a mixture of both.

An article published in Focus magazine states that, “In recent decades, researchers have increasingly appreciated the multifaceted contributions to the etiology and pathogenesis of eating disorders, including genetic, familial, developmental, and psychosocial influences” (Yager, et al., 2005).

Are eating disorders biologically based? In the sense that certain genetic traits must be present in order to render a person vulnerable to developing an eating disorder, yes. In the sense that, if the various genetic markers are present then the person in question will develop an eating disorder regardless of any other factor, no. Recent research on the genetic factors that contribute to the formation of an eating disorder reveals that, while genes are indeed a factor, they alone cannot cause an eating disorder. Cynthia Bulik, Director of the UNC Eating Disorders Program at the University of North Carolina at Chapel Hill School of Medicine, states that, “Genetics loads the gun, but environment pulls the trigger.” In other words, the genetic vulnerabilities must be there, but an eating disorder won’t emerge unless the right environmental conditions are present.

In an article co-written by Bulik and Suzanne Mazzeo, Associate Professor of Counseling Psychology at Virginia Commonwealth University the authors posit that, “Ultimately, the elucidation of causal models for eating disorders will no doubt include various types of genetic and environmental interplay…Clinicians and researchers must become educated in the nuances of GxE (genetic and environmental) interplay and avoid perpetuating purely environmental or purely genetic conceptualizations of eating disorder etiology” (2009).

This speaks to the role of the family system, as one of several environmental factors, in potentially providing an eating-disorder-friendly habitat, so to speak, for a child whose genetic makeup renders her vulnerable to developing an eating disorder. Mazzeo and Bulik note that, “For decades, parenting styles have been unrightfully blamed for causing eating disorders. Considerable care must be taken when discussing GxE interplay not to convey the message that somehow parenting is to blame for these pernicious illnesses. Conversely, a purely genetic explanation should not be taken to mean that parents need not examine their parenting style and the influence it might have on children” (2009). They go on to say that the child’s genetically influenced constitution also shapes how that child will react to a particular parenting style. For example, a child with the genetic constitution for developing an eating disorder might be much more aware of physical appearance than his/her differently gened siblings. The child may ask for more feedback about his/her appearance, thus generating more comments about appearance from his/her parents (and others) than the other siblings receive.

So the interplay of genetics and environment is complex, and begins early on with environmental factors, such as parenting. Other environmental factors include life events and media influence. Authors John Briere and Catherine Scott report on how “Research suggests that individuals with eating disorders (EDs) are relatively likely to have been abused or neglected as children, or to have been victimized in adolescence or adulthood. These experiences, in turn, are often associated with a range of psychological symptoms, as well as, in some cases, a more severe or complex ED presentation” (2007).

It’s important to recognize that difficult life events, from a major move to physical or sexual abuse (which have been shown to be risk factors for bulimia), are experienced differently by a person who tolerates distress poorly, and a person who tolerates distress well. The ability to tolerate distress is, in part, genetically influenced, but also has to do with how distress tolerance was modeled and taught in the person’s family.

With regard to cultural notions about ideal body size and shape, everyone is exposed to media images of ultra-thin ideals, but not everyone develops an eating disorder. These things will affect someone with the “right” genetic markers differently from someone who does not have them. But how parents and other elder family members handle the media imagery, and whether they share the idealization of ultra-thin bodies, also influences the child.

Suffice it to say, eating disorders are complex, and their causes are equally complex. No one factor accounts for the formation of an eating disorder. Eating disorders are best understood via a biopsychosocial model, which takes into account genetics, our personal selves (thoughts, feelings and behaviors) and the familial and social contexts in which we grow up and live. When it comes to treating disordered eating, the latter two must be addressed. We can’t change our genetic makeup, but we can change the way we think, the way we manage our emotions, the way we behave, and, in adulthood, the circumstances in which we live. And we can avail ourselves of therapies that focus on healing the damage done by earlier experiences.


  1. Briere, John and Scott, Catherine. (July, 2007). Eating Disorders: The Journal of Treatment and Prevention. “Assessment of Trauma Symptoms in eating Disordered Populations.” Vol. 15. No. 4.
  2. Bulik, Cynthia M. and Mazzeo, Suzanne E. (January 2009). Child and Adolescent Psychiatric Clinics of North America. Vol. 18. No. 1.
  3. Yager, Joel; Devlin, Michael J; Helmi, Katherine A; Herzog, David B; Mitchell, James E; Powers, Pauline S; and Zerbe, Kathryn J. (Fall, 2005). Focus. “Eating Disorders.”

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