And gentics. Some people/families are just more prone to cancer than others.

A long while ago i read about this and a link to wealth. Of those families with know genetic problems, the poor ones seems to have actively dealt with the issue internally after realizing the problem. They adopt, have fewer children, or use surrogacy. They cannot afford sickly kids. But wealthy families did not, the best examples being those royal families with known problems.

Personally, my cancer risks went way up when my heavy-smoker uncle died of throat cancer. Going from zero cancer in related family to "some" moved me up the charts.