Grandparent DNA Test | DNA Testing Glossary

A grandparent DNA test determines whether a biological relationship exists between a grandparent and a grandchild. Families often use this test when the alleged father is absent, deceased, or unwilling to test, since the grandparents carry DNA that their son would have inherited and passed on. Testing both grandparents (rather than just one) strengthens the result because the lab has more data to work with. The lab compares genetic markers between the grandparent(s) and grandchild and calculates a likelihood ratio. Including the mother's sample, when available, also improves accuracy by allowing the lab to isolate which markers the child inherited from the paternal side.

Related Terms

Kinship DNA Test, Sibling DNA Test, Avuncular DNA Test, Reference Sample, Probability of Paternity

Source

National Human Genome Research Institute — Genetic Testing FAQ