Inherited breast cancer is associated with germline mutations in ten different genes in pathways critical to genomic integrity. BRCA1 and BRCA2 mutations confer very high risks of breast and ovarian cancer. p53 and PTEN mutations lead to very high breast cancer risks associated with rare cancer syndromes. Mutations in CHEK2, ATM, NBS1, RAD50, BRIP1, and PALB2 are associated with doubling of breast cancer risks. In addition, biallelic mutations in BRCA2, BRIP1, and PALB2 cause Fanconi anemia. The convergence of these genes in a shared role reveals underlying biology of these illnesses and suggests still other breast cancer genes.