The European Royal Family

Hemophilia has affected the Royal Families of Europe for the last few centuries. The origins of the disease in the family have been traced back to Queen Victoria, though it has been shown that neither of her "parents" were affected or were carriers.  Statistics now show a 33% spontaneous mutation of hemophilia that may have caused this.

It used to be the trend that royalty had to marry other royalty, which was very conducive to keeping the disease within the Royal Family. With the more relaxed rules of the Royal Family in the current time, the disease hasn't been seen in almost 100 years in the family.
 

Click here for a larger version of the Royal Family Pedigree!