I'm guessing that's why some of the SPY's dividends are unqualified. Page 34 of the same website contains the tax information for the DIA. The DIA paid $2.93 a share in 2008, all of which is qualified.
The mutated gene is passed down through a family, and each generation of children can inherit the gene that causes the disease. Rarely, one of these monogenic diseases can occur spontaneously in a child when his/her parents do not have the disease gene, or there is no history of the disease in the family.
Some diseases are passed from one person to the next through infections such as influenza. Others develop because of environmental problems such as smoking or through cellular mutation. The medical community works to understand and treat all forms of human disease.