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.
The exact cause for many rare diseases remains unknown. Still, for a significant portion, the problem can be traced to mutations (changes) in a single gene. Such diseases are referred to as rare, genetic diseases. Many of these genetic mutations can be passed on from one generation to the next, explaining why certain rare diseases run in families. It is important to keep in mind that genetics are just one piece of the puzzle.