Risk Factors: Genetic

About 5% to 10% of breast cancers are thought to be hereditary, caused by abnormal genes passed from parent to child.

If you’ve had one first-degree female relative (sister, mother, daughter) diagnosed with breast cancer, your risk is doubled. If two first-degree relatives have been diagnosed, your risk is 5 times higher than average.

Women with a father or brother who has had breast cancer also have a higher risk of breast cancer.

Additional Resources:

https://www.breastcancer.org/risk/factors/family_history  
https://www.breastcancer.org/risk/factors/genetics
https://www.cancer.org/cancer/breast-cancer/risk-and-prevention/breast-cancer-risk-factors-you-cannot-change.html