How much do genetics count?
About 20 to 30 percent of women with breast cancer have a family member with the disease. Women whose close relatives have breast cancer have a much higher risk of getting it. If a mother, sister or daughter has the disease, a woman has about double the risk. With two first-degree relatives with breast cancer, her risk increases five-fold, according to the American Cancer Society.

A women whose father or brother has breast cancer also has an increased risk, but exact risk has not been established.

About 5 to 10 percent of breast cancer cases are thought to result from gene mutations inherited from a parent. The most common mutations are BRCA1 and BRCA2 (acronyms for breast cancer genes 1 and 2). Women with an inherited BRCA1 or BRCA2 mutation have up to an 80 percent chance of developing breast cancer, ACS reports.

There is some good news for women saddled with a family history: A recent study in the Archives of Internal Medicine found that among women whose mothers or sisters had breast cancer, those who breast-fed had a 59 percent lower risk of breast cancer compared to women who had never breast-fed. Breast-feeding was comparable in lowering risk to taking the estrogen-blocking drug Tamoxifin for five years, the study authors said.

If you do have breast cancer in your family history, talk with your doctor to see whether you may need earlier and more frequent screening or genetic testing.