Potentially, yes. But, you don't give enough information to explain an answer. No man is "required" to pay child support until a court rules that he is the "legal" father and has a duty of support. Generally, by signing to be placed on the birth certificate, the man creates a presumption of paternity. Whether that presumption can later be rebutted by DNA testing depends on a lot of specific facts, most important of which is how long it was between signing off on the birth certificate and obtaining the DNA testing and then doing something about it. You should consult an attorney who can identify all the important facts and then apply the law to those facts.
Answered on Dec 12th, 2011 at 9:23 AM