I go for a physical every other year or so and have been blessed with excellent health, no matter how badly I abuse myself. My dad had some polyps removed, but I believe it was after he was 50.
AFAIK, no one else in the family has ever had an issue with this stuff. My doc. has told me more than once I don't need to even think about a colonoscopy until I'm 50. I'm 36 now. How long should I wait?