In some families, both the men and women are susceptible to breast cancer. When breast cancer runs in a family, it can run alone, or as part of a broader illness that includes other cancers. For example, in some families, breast cancer and ovarian cancer are both common. Some women will even have both tumors. In such families, breast cancer is just one problem in this broader illness.
Breast cancer has strong genetic components as well as environmental components.
So, it's a matter of nature and nurture , not nature versus nurture. Almost by definition, cancer never has a single cause. You can think of hits as a measure of damage. Radiation, chemicals, infections, hormones, and other factors can deliver hits to DNA after birth. In other words, the genes for these disorders have a strong influence on breast cancer risk.