Topic summary
First-degree relative
Extracted from the Wikipedia article Coefficient of relationship.
Human relationships
A first-degree relative (FDR) is a person's parent (father or mother), sibling (brother or sister) or child (son or daughter). It constitutes a category of family members that largely overlaps with the term nuclear family, but without spouses. If the persons are related by blood, the first degree relatives share approximately 50% of their genes. First-degree relatives are a common measure used to diagnose risks for common diseases by analyzing family history.