A direct paternity test is always the best option to determine a biological relationship between a child and alleged father. In instances where the alleged father is unavailable or unwilling to participate in DNA testing, a grandparentage test is another option to consider.
A grandparent DNA test determines whether a couple could be the biological grandparents of a child. It is an indirect way to determine family relationships when an alleged father is not available for a paternity test. The mother's participation is encouraged to expedite analysis; motherless grandparent tests take longer to complete because of the extended analysis required.