Short answer? We don't know. But here are some factors that influence your risk.
Rheumatologist Susan M. Goodman, M.D., attending physician at the Hospital for Special Surgery in New York City, explains what we know about why RA develops in the first place. Hint: Not a lot.
It's not really known what causes RA, although there's a lot that's known about it. There are specific genetic factors that are clearly linked to an increase in RA risk, but they don't really cause it per se. There are certain antibodies that your body can produce that can drive the disease
forward and cause more severe disease. It's one of those many diseases that's a combination of something in your genes and then something in the environment that triggered the illness and result in the inflammatory arthritis that typifies the disease.