I am going to have to say that your first fact did shed some more light on the issue for me in regard to upbringing. I will have to agree with you that environmental factors during childhood can heavily affect the development of an eating disorder that can't be controlled, so in this case I will give you a ∆. In regard to your argument about peer groups influencing factors such as vomiting to lose weight, I would like you to elaborate more, because I still believe that that is caused by ignorance of what an individual perceives as healthy or unhealthy. An individual that subjects them to that is unaware of how unhealthy it is, but continues to do so due to a distorted view of what is "attractive" to them.