Interesting article from the New England Journal of Medicine concerning Lupus and genetic associations.
http://content.nejm.org/cgi/content/full/NEJMe0800096?query= TOC
I'm not saying the genetic associations aren't there...I'm saying there must be other things (infection, stress, diet, environmental) to activate them.
And Thank God - could you imagine if this were just genes and you were doomed to get these diseases?