Paternity refers to the legal determination of who is the biological father of a child. Normally, the identity of the biological mother is known yet the father's identity might not be certain. When I started my law practice in 1978, the type of testing available then would only determine if you would be more likely than not to be the biological father.
Today, we have sophisticated DNA testing that allows for a 99.9% certainty of parentage. The DNA sample taken from the child and potential father is examined by a scientist trained to determine the significance of the test samples. DNA testing is generally only done if a party contests paternity. Typically, a presumed father will ask for DNA testing to ascertain the parentage of the child and to insure that if he is legally responsible to pay support, he is paying support for a child that is his.
A potential father may also demand testing to establish that a child is his in order to have legal standing to ask for custody and visitation with the child.
Paternity issues, like most family law issues can have far reaching implications, both financially and emotionally. For these reasons, it is important to secure the services of a qualified attorney experienced in the area of family law.