Pennsylvania paternity determinations are rarely based on genetics. Paternity is currently established through the common law constructs of presumption by paternity and paternity by estoppel. These constructs are rooted in public policy that seems more akin to a legal fiction than biology. The controlling public policy is created by the legislature and cannot be established by the judiciary.

Parents can acknowledge paternity to avoid court determination. Parentage can be acknowledged through a birth certificate, a child support action or dependency matter. An acknowledgement usually prevents further legal inquiry into parentage.