Certain cancers have been found to run in families. Although some cases have been linked to shared behaviors, such as smoking, others are thought to be passed from one generation to the next through abnormal genes. According to experts, only about 5 to 10 percent of all cancers result directly from mutations inherited from a parent. Two specific inherited genes, BRCA1 and BRCA2, are associated with an increased risk for breast and ovarian cancers and several additional other types of cancer. A child of a parent who carries a mutation in one of those genes has a 50 percent chance of inheriting the mutation.