Genetics certainly is a complex area and the genetics of rheumatoid arthritis are complex. "The genetic component of RA is widely investigated: the strongest gene association is considered to be the one with the human leukocyte antigen (HLA) region, particularly the HLA-DRB1 genes accounting for about two-thirds of the genetics of RA." Arthritis research & therapy
There is one thing that has been shown to increase the risk of rheumatoid arthritis, that can be controlled, and that is smoking. Recently, it has been reported that smoking is involved in the development of many autoimmune diseases such as RA, Lupus, Systemic sclerosis, Multiple sclerosis and Crohn's disease.
RESOURCES: Rheumatoid arthritis and smoking: putting the pieces together