The conclusion of a study newly reported, http://www.abc.net.au/pm/content/2011/s3353425.htm is that women without mutations associated with breast cancer, but from mutation carrying families, are not at increased risk. Even if there is a solid family history that doesn't mean the genes responsible are inherited.
I've been a skeptic about the value of family history in preventative medicine. Folks may be at increased risk through their genetics but confused about their disease history. What you don't know could kill you.
It's the best argument I know for getting the facts for your situation, taking a DNA test for health, and getting the ancestral information that come with it as a bonus.