By now, most of us are probably pretty familiar with the BRCA1 and BRCA2 (pronounce them “bracka 1 and bracka 2”) genes. Identified in 1990, they were the first genes positively linked with an increased risk for breast cancer. Since then, it’s been determined that women whose heritage is Ashkenazi Jewish are about 10 times more likely to carry one or the other of these genes than the regular population. The bad news is, abnormalities in these genes put the women who carry them at 50% to...