A first degree relative is a family member who shares about 50 percent of their genes with a particular individual in a family. First degree relatives include parents, offspring, and siblings.


When you visit with a genetic counselor, one of the first things that they might ask you about is your first degree relatives. And by that they mean your parents, your sisters and brothers, and your children. Each of your first degree relatives shares half of their genetic information in common with you, and so we would expect that things that occur in families are likely to be revealed when we look at relatives who are closely related.

- Barbara Bowles Biesecker, Ph.D.