Why can’t DNA tests prove with 100% certainty that a tested man is the father?

A DNA test cannot prove that a tested man is the biological father of a child with 100% certainty because the possibility that the tested man is matching the child due to random chance (coincidence) can never be completely ruled out. However, most courts consider a probability of paternity of 99% or greater as strong and sufficient evidence of paternity. Current DNA test batteries typically produce probabilities of paternity greater than 99.9%.

Posted in: Paternity Testing - Basics