How to prevent hereditary breast cancer?

See below. Keep current on mammography. Stop smoking, maintain an ideal body weight. Depending on how strong your family history is, and if you have a proven genetic mutation, you could be a candidate for prophylactic mastectomy, with or without removal of the ovaries. Visit with a medical oncologist to find out your options.
Prevention. Implies "fixing the underlying defect" and this sort of genetic engineering has not arrived - vectoring the gene in may not lead to its propoer regulation (turning on and off properly for instance). Early detection--proper cost effective screening, or avoidance of co-factors for induction seem resaonable choics.