All I know is that I am the only woman on either side of my family without rheumatoid arthritis, and an aunt, along with myself, suffers from lupus. It is sufficient to say there are some studies that have linked autoimmune diseases with heredity, but studies only see patterns, not fact. Another study is that autoimmune disorders have also been linked to excessive doses of antibiotics during childhood (giving the immune system no reason to work). I myself have both "causes", but these disorders can attack anyone without cause, or not attack someone with the genes for it. My advice would be to get it checked before things progress, and if the tests come back negative, that's wonderful!