Do all women with a family history of breast cancer end up with it?

No: While there is an increased risk, it is not 100%. Even in women who have brac1 or brac2 abnormalities have a very high risk of breast carcinoma (and ovarian cancer among others), but it is not a guarantee that having a mother, aunt, or grandmother with cancer means you will automatically get breast cancer. You should have increased screening though.

No : There is an increased risk for you to have breast cancer due to family history of breast cancer- compared to someone who does not have family history of cancer- but absolutely not 100%. The risk also will be higher if you have precancerous state like dcis or history of breast biopsy, the age , age of starting menses, age of first pregnancy etc. You can use gail calculator to figure out your risk.