The presumption of paternity in Allegheny County has evolved over the years. Originally, paternity was presumed if a man and woman were married and the woman gave birth to a child. Unless the man had no access to the woman or had been proven to be sterile, the child would be legally presumed to be his. Because of this presumption, no third party could assert their own claim of paternity to the child.
Now, paternity is presumed when a marriage is in tact, however after the Pennsylvania Supreme Court decided Brinkley v. King, a third party may now assert paternity when a marriage is either no longer in tact or if there was never a marriage to begin with. The third party still may not attack paternity if the marriage is intact. This barrier to paternity is known as estoppel. If a third party attempts to attack paternity of a child who is part of an intact family, they will be estopped.
If you are the presumed father and you begin to doubt that you are in fact the father of the child, there are a few things you can do. First, if you are on the birth certificate yet not married to the mother and she filed for support, you may refuse to sign an acknowledgment of paternity. If your doubts arise once the child has become older, the process is trickier. If evidence surfaces that the mother of the child has been defrauding you, it is important that you stop filling the roll as father. By cutting ties, you are shielding yourself of claims from the other party that you knew you were not dad yet still acted as dad anyway. If you remain in the roll of dad, this could result in you still being considered dad indefinitely and still be required to pay support (if so paying).
If you have stopped acting as father, you may petition the Allegheny County Court of Common Pleas, Family Division through a motion to see if you can be granted a paternity hearing. If granted, the family court will determine in this hearing if you are to be granted a blood test and a final judgment on the paternity of your child.