Fifty-six percent heritability -- that's a fairly large contribution of genes.

Genes load the gun, and environment pulls the trigger. These people who are genetically disposed to anorexia nervosa may be more sensitive to those environmental triggers, like dieting after seeing a fashion magazine.

Anorexia nervosa is not simply a disorder of choice. There is a clear genetic [cause] for this disorder that we need to incorporate into our understanding of what anorexia nervosa is.

For centuries, we have been under very false stereotypes and misconceptions about what causes anorexia nervosa.

We need to stop viewing them as a choice. The patients feel guilty; the providers tell them things like they should just eat; parents are blamed; the insurance companies won't fund treatment because they think it's a choice. It's held us back for decades.

Of course, the gene pool didn't change. The environment has indeed changed and cultural pressure to be thin has been greater on the younger part of the study group.