Each person’s genetic fingerprint is unique—a fact that makes this type of testing so reliable. A biological child shares 50% of their DNA with the biological father and 50% with the biological mother. A DNA paternity test compares a DNA sample from an alleged father and a DNA sample from a child (minor or adult) to determine whether the two individuals are likely to share or not share a father/child biological relationship. With the exception of any mutations—which are taken into account by geneticists when determining probability of paternity–the man being tested must match the child’s data at every marker tested in order to be considered the biological father.