The role of socio-cultural factors in the development of eating disorders
The common belief that eating disorders are a result of environmental factors has been thoroughly debunked. In fact, the scientific consensus is that they are a result of genetic factors. There are many studies that have shown that the rates of eating disorders among people with identical twins is higher than in people with fraternal twins.
This is not to say that socio-cultural factors have no role in the development of eating disorders; they certainly do. But they play a secondary role, one that is less important than genetics. This can be seen by looking at the rates of eating disorders among people in different cultures. The rates differ greatly between cultures, as shown by this study: https://www.ncbi.nlm.nih.gov/pubmed/24885589