Holland et. al (1984) - found there is some genetic basis for anorexia amongst families, mz twins had 55% concordance, whilst dz twins had only 7%
however nature/nurture debate
Kendler et al. (1991) - risk factors for bulimia included: being born before 1960, poor parental care, dieting and fluctuating weight, slim ideal body image, low self esteem, feeling a lack of control over one's life. In mz twins concordance was 23%, and in dz twins it was 8.7%
The American Psychiatric Association (1994) reports there is an increased risk of eating disorders amongst first-degree biological relatives of those diagnosed - higher prevalence than general population.
Minuchin et al. (1978) suggested that the development of anorexia serves the function of preventing disagreements within the family, e.g. preventing marriage break up by diverting attention onto themselves.
Family relationships are thought to be a central feature in eating disorders and a lot of therapy is based around it - family therapy and is currently most significant form of intervention for eating disorders.
Also, if you want my tuppence worth I think that families do play a large part in the initiation of eating disorders, especially as they occur so frequently in teenagers thus still living at home the environment brought up in is a key feature. For example, living in a family environment where there isn't much control anorexia may prevail as it attempts to bring about some control and structure in to their lives.
Furthermore, if you have a parent, usually a mother, that is constantly on a diet etc. it is logical to assume that through some form of conditioning the child learns that same behaviour as been brought up with their main care-giver having those values of losing weight, loooking good etc.
Is this for uni? If so, I suggest you get in contact with BEAT as they can give your details and pass you on to people who are willing to share their experiences for research purposes, i.e. for studies, dissertations etc I believe.
Good luck and I hope that helps :]
xx