In 1991 Joyce Wadler, a 43 year-old New York City reporter, had breast cancer which was caught early and successfully treated. She thought her cancer problems were over, she knew of no other cases of breast cancer in her family. Four years later Ms. Wadler was diagnosed with advanced ovarian cancer. She also learned that she was carrying a genetic mutation, BRCA-1, which has been found in Ashkenazic Jews and which gives women a higher risk of breast...