Well first this is not a "quick" question, it is a very complex issue.
The state where the child is living can matter.
Is the real bio father making a claim ?
Did the "father" know he was not the father when he signed the birth certificate.
But at this point, yes he will have to pay, in most states he will be able to contest any order in court asking for a DNA test. In some states he may not be allowed to, and in others only have a number of years to challenge after child is born.
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