I wanted to chime in on this subject. I'm glad you bought this up. I have read reports and heard on the news that people who are from low socio-economic backgrounds, have emotional issues, uneducated, etc... seem much more likely to have an illness, disease, or poor health. I personally take offense to that mass grouping. I also do not fit the bill of the above categories.
I have autoimmune issues. Prior to all the issues I have experienced in more recent years, I led a life where I felt extremely blessed and seemed to breeze through life. I have always had a lot of fun, enjoyed life, and am surrounded by people who care about me. I am not one to stress out to the max. I have a college degree and am not from a lower socio-economic background. In my very late 30's, I started a path where I have been hit with immune problems. When the immune problems started, my family and friends could not believe it, as I had always been seemingly quite healthy. I could not believe it either!! I now have accumulated a host of immune problems. In my journey, the key question physicians have consistently asked is, "Are there relatives presently, or in your background, that have a history of immune problems?" When I started investigating, I found there was a history of immune problems in some of my relatives. Rheumatoid arthritis, diabetes, and osteoarthritis seemed to be the prevailing issues.
I am like Jan and others in thinking you can get certain smaller health issues from emotional issues, but I am not convinced on the big issues. Since the AN diagnosis, I have often wondered about the history of tumors in my family. In my case, I find it interesting that my father, maternal aunt, maternal grandmother, and maternal grandmother's sister have all had tumors. Three of the four had cancerous tumors, with one having mutiple benign tumors. My father's tumor was also considered a head and neck tumor. He had a tumor behind his ear that was malignant. It was considered to be a parotid gland tumor (salivary). It was a Class 3 tumor. He had radiation for over two months almost six years ago. He is now past the five year status and is cancer free!
In summation, I think heredity plays a large role in what we have in regard to health issues and mental issues. Like Jill Marie, I think if we look at children, who are quite young and have not even been burdened by life and have been diagnosed with tumors, etc..., it gives an insight that should show the medical community that categories are not always the right way to group individuals together with health/mental issues. I don't think there is a perfect mold for illness. This is just my humble opinion!