While it is obvious that every child has a biological father, not every child has a father in the legal sense. Unless paternity has been established, no one is the legal father of said child. Paternity is automatically established if the parents are married to each other at the time of the child's birth. In the case of unmarried parents, paternity may be established at the birth of the child, or any time thereafter, by both mother and father signing a "Voluntary Acknowledgement of Paternity." Only once paternity is established, can a father's name be placed on the child's birth certificate.
If the father signs the Voluntary Acknowledgement of Paternity, but the mother refuses, then the Department of Public Welfare registers it as a claim for paternity, meaning that the father will be notified of any proceedings for adoption of the child. In an instance where the mother refuses to acknowledge paternity, if the father wants other rights to the child, such as custody or visitation, then the father must go through the courts to have paternity "involuntarily" established, usually by the filing of a "Petition to Determine Paternity." Once Petition to Determine Paternity has been filed, then the court will order DNA testing and, if appropriate, enter an order of paternity.
If a mother files for child support against a father who refuses to acknowledge paternity, then the court can order both parties to appear for genetic testing. A court can find that the alleged father is child's biological father to a 99.9% certainty. DNA testing is not invasive and usually consists of obtaining a saliva sample through a mouth swab.
Establishing paternity means much more to a child merely having a father named on his or her birth certificate. For example, both the father and child will be entitled to inheritance rights should one of them pass away before the other. Establishing paternity also enables the child to benefit from the father's medical insurance benefits, life insurance benefits, and Social Security and Veteran's benefits.