Third-degree relatives are a segment of the extended family and includes first cousins, great grandparents and great grandchildren. Third-degree relatives are generally defined by the expected amount of genetic overlap that exists between two people, with the third-degree relatives of an individual sharing approximately 12.5% of their genes. The category includes great-grandparents, great-grandchildren, grand-uncles, grand-aunts, first cousins, half-uncles, half-aunts, half-nieces and half-nephews.
- "First, Second and Third Degree Relative". bcbst.com. Blue Cross Blue Shield of Tennessee. Retrieved 18 August 2016.
- Ludman, Mark (2009). The Encyclopedia of Genetic Disorders and Birth Defects. p. 101. ISBN 9781438120959.
- "29 CFR § 1635.3 - Definitions specific to GINA".