The Genetic Influence: Heritability of Eating Disorders

The heritability of eating disorders is a common research topic. In the field of genetics, heritability measures how much genetics influence the development of a given characteristic within a group of people.

Note that the heritability of an eating disorder is not equivalent to the probability that a mother (or father) with the eating disorder will have a child who also has it. Instead, if an eating disorder is highly heritable, it means that much of the variation in the presence or absence of that eating disorder in a group of people is due to the genetic variation among group members.

What accounts for the rest of the variation in eating disorder development? That's where a person's individual environment -- different from the environment of everyone else -- is important. Factors, such as family systems, abuse, media and other influences work with what genetics provides. Both genetics and environment contribute to whether we develop eating disorders or not.

Heritability of Anorexia Nervosa

The heritability of anorexia has been studied in a variety of ways, but the general consensus is stunning. Estimates of the heritability of anorexia generally range from 0.56 to 0.76. In other words, the question of whether you will develop anorexia or not is 56 to 76% determined by your genetic code -- something entirely out of your control.

To be as clear as possible, this does not mean that 56 to 76% of all children of those with anorexia will end up with anorexia. So what does it mean? Imagine that all of the factors that determine whether a person develops anorexia -- age, gender, media exposure, family problems and so on, in addition to genetics -- get to "vote" on whether anorexia develops or not. Genetics gets 56% to 76% of the vote. But again, it isn't the entire vote. In general, nongenetic factors complete the work that genetics start.

Heritability of Bulimia Nervosa

Bulimia's heritability is no less striking. Studies since 1991 report heritability estimations for bulimia as between 0.3 and 0.83. The majority of studies, however, point to heritability between 0.4 and 0.6.

Heritability of Binge-Eating Disorder

Not to be forgotten, binge-eating disorder (BED) also seems to be significantly heritable. Two studies report BED heritability at 0.41 and 0.57, respectively.

What Eating Disorder Heritability Means

So do we throw up our hands and say that we can do little, since eating disorders are so tied to our genetic makeup? No. Genetic code has a strong influence, but as stated above, nongenetic issues add to a person's genetic predisposition to an eating disorder to make it more likely to develop. Those issues are places for eating disorder clinicians and educators to go to work.

Factors that are changeable can be the targets of preventive measures in families with a history of anorexia, possibly keeping the disorder from developing in children. Strategies may include early reinforcement of healthy body image, teaching parents how to model healthy eating (and not hide food from their kids, for example) and education on how to be media-savvy (so that young girls, especially, can be thoughtful in their critique of advertisements and other media depictions of extreme thinness).

And when an eating disorder does develop? It's not the end. Good eating disorder treatment is out there, and many respond well and move in to more normal lives. No matter when a person decides that he or she doesn't want to be controlled by food, there's plenty of room to choose life-giving options.