Personalization of care through precision medicine and, more specifically, genetic testing is altering the treatment of breast cancer. Genetic testing is used in germline and tumor testing, with each providing distinct data to guide management. Germline testing supports more accurate risk evaluation to inform screening and risk-reducing medical and surgical strategies. Tumor testing can inform cancer recurrence risk assessment and cancer treatment options. This article reviews how genetic testing informs treatment and potential risks for a patient with breast cancer and her family. Hereditary cancer genetic testing of family members should include a discussion of potential results, adverse effects, clinical management options, and insurance coverage and address concerns about privacy or discrimination. Genetic professionals are available to assist with educating, testing, and treating patients with increased cancer risk.