Breast cancer occurs when the cells in the breast grow abnormally without any restriction. This happens when there is a mutation (change or alteration or variation) in the genes that control the growth of these cells. Inherited gene mutations are those that are passed down from the parents to the children and are present in all the cells of our body. Though inherited gene mutations are responsible for a much lesser number of cases as compared to acquired gene mutations, the risk of developing breast cancer is much higher in people who have an inherited gene mutation as compared to those who have acquired it in their lifetime. Individuals with inherited gene mutations that predispose to cancer are often affected by the cancer at an early age.