There doesn't appear to be one, stand-alone reason that explains why one person has a mood disorder and another does not. It's much more likely that several factors come together to increase the risk. Although gender, race, and income don't have much influence on risk, several other factors do. The most important is family history, with quite a bit of help, it seems, from some influences that originate outside a person's DNA. There is a popular belief that creative people are prone to bipolar disorder, and it is true that many accomplished people, past and present, have been linked to the disorder. Preliminary evidence supports this widely held view, although the studies are small in scale.