What causes colorectal cancer, and who is more likely at risk of developing it?

Multiple causes: There are multiple causes to colorectal cancer. It is a combination between genetics, and what your colon & rectum are exposed to over the course of many decades. Clearly the most at-risk patients are those with a strong family history and a documented history of gene mutations, namely something called fap and hnpcc. Take a look at some of my other posts on reducing your risk.

Can be genetiic: Can run in the family but there is an increased incidence with age. That is why a colonoscopy is advocated over the age of 50.