People often think about certain versions of a gene as either good or bad. One that leads to depression is bad while one that protects you from HIV infection is good. For most genes this is almost certainly too simplistic a view. Many versions of genes can be good or bad depending on your situation.
Imagine a medical disease that afflicts eighteen million people in the U.S., for which more than 160 million prescriptions were filled in 2008, that is one of the leading causes of disability in the U.S., but a disease for which no definitive medical model of pathology exists.