What defines close relatives for purposes of determining breast cancer risk?

When analyzing whether cancer could be inherited, it’s important to evaluate close relatives on both mom’s and dad’s sides of the family. Our close relatives are our first, second and third degree relatives.

People you share 50 percent of your DNA with, such as siblings, parents and children, are your first-degree relatives.

Nieces, nephews, aunts, uncles and grandparents – people with whom you share 25 percent of your DNA – are second-degree relatives.

First cousins, great-grandparents and great aunts and uncles – people with whom you share 12.5 percent of your DNA - are your third-degree relatives.