Contrary to what many people believe, eating disorders are not just about the food - the food is only a symptom of what is really going on for the person. Eating disorder can affect anyone from any walk of life - anorexia used to be described as the "rich teenage girls disease" - not the case anymore - both boys and girls are now effected and it has been detected in children as young as 4/5.
There is no one cause for eating disorders and where parents, family can contribute to the symptoms through lack of knowledge/understanding, they are not the cause. Because the sufferer feels out of control in other areas of their life and food is the one area they feel they are in control, whether it is through under-eating, binging, purging. It's a very secretive and lonely condition hence the importance of family gaining an understanding so that they can help. If the sufferer refuses to get help from a counselor/therapist it can really help if the parents find a therapist they can trust to help them understand the condition and guide them - this in turn can show their child that they really care and in some cases recovery is possible. Ideally though for full recovery its best if the sufferer child or adult finds a therapist that they can trust and confide in to help them work through all the issues holding them back from leading a full life. Therapy can take a while as it can take someone with an eating disorder a while to build up trust - part of the therapist's job is help the sufferer to begin to like themselves, to build up confidence and self esteem by helping them to look at all areas of their life - emotional, mental, social, spiritual, friends, school, work.......
It's very important that parents get some support and learn about the condition in order help their child recover and for adult sufferers its good if a family member, partner or friend learns about the condition to help support them - these are not personal therapy sessions but educational sessions and initially are possibly more important the sufferer themselves attending. Even if the sufferer won't always admit it they are generally pleased that someone would care enough about them learn about the condition. It is also vital to have the support of a good GP and to have regular checkups as the therapist can't be responsible for medical issues.
People say you never recover from an eating disorder that is only possible to manage it. I believe that it is possible to recover - it takes time, patience and commitment but it is possible.