There’s a pretty high correlation between family history and colorectal cancer. A person has to be cautious when choosing their ancestors. ;)
Here’s a page that has an article about the genetic connection for colon cancer:
http://www.sciencedaily.com/releases/2003/10/031014071619.htm
There are also links to other articles about colon cancer and genetics, and an article about fruits, veggies and colon cancer risks.