When a paternity test is needed but the alleged father is deceased, incarcerated, unavailable, or unwilling to participate, a biological sibling of the alleged father (his brother or sister) can undergo testing to determine a DNA relationship. This is called an avuncular (aunt/uncle) DNA test. The results can help indicate or exclude a biological connection between the child and the alleged father.

Additionally, an avuncular DNA test can serve as a substitute for a sibling DNA test. If one potential sibling is unavailable or unwilling to be tested, their biological child’s DNA can be compared to the other potential sibling to determine a genetic relationship.