Myth: If breast cancer runs in your family, it automatically means that you’re going to get it too.
Fact: Getting breast cancer is not a certainty, even if you have one of the significant risk factors, like a strong family history or a known breast cancer gene abnormality. For example, of women with a BRCA1 or BRCA2 inherited genetic abnormality, 40 to 80 percent will develop breast cancer over their lifetime; 20 to 60 percent won't. All other breast cancer risk factors are associated with a much, much lower probability of being diagnosed with breast cancer.
Information courtesy of BreastCancer.org