what is a first degree relative

A first-degree relative is a family member who shares about half of their genetic information with specific other individuals in their family. They include a persons parent (father or mother), full sibling (brother or sister), or child. First-degree relatives share approximately 50% of their genes if they are related by blood. They are a common measure used to diagnose risks for common diseases by analyzing family history. The term "first-degree relative" largely overlaps with the term "nuclear family," but without spouses.