Prostate cancer is one of the most heritable malignancies: it is estimated that ~50% of prostate cancer risk is due to genetic factors. In addition to common polymorphisms that influence cancer predisposition, we have recently determined that rare highly-penetrant cancer predisposition genes are frequently mutated in men with aggressive/advanced prostate cancer. These predisposition genes link prostate cancer with other heritable cancers such as breast and ovarian cancer in the context of BRCA1/2 mutations and colon cancer in the context of mismatch repair gene mutations. Importantly, mutations in these DNA repair genes identify families at risk for cancer and support precision oncology strategies that exploit responses to specific therapeutics such as PARP inhibitors.