It is not unknown to many that men told to have fathered a child sometimes suspect if they truly are the father of the child. Now, men - and even mothers - need not wait for nine months or even years after before finding out the real or biological father of the child.
DNA testing and biomedical technology is so advanced nowadays that DNA paternity testing can be done even with the child still in the mother's womb. This is what DNA test laboratories call the Prenatal DNA Paternity Testing.