Your situation appears to be very complex if there is a judgment out there naming someone else as the father. You would have to set aside that judgment and it is questionable if you even have any standing or right to be able to do that.
You seriously need to talk with a family law attorney in your area.
As Attorney Montgomery stated this is a complex issue and really can't be answered in a forum such as this. There are so many factors that have to be considered. You don't say how paternity was established. Have you been in the child's life?
Contact an attorney in your area to review the facts with you so you can receive a more iformed response.
Good luck and I commend you for wanting to be a part of the child's life.
Note this answer does not constitute legal advice, and should not be relied on. Each situation is fact specific and court specific, and it is not possible to evaluate a legal problem without a comprehensive consultation and review of all the facts and court pleadings filed in the case. This answer does not create an attorney-client relationship
You say "never showed up for dna testing"--but you don't say when. DNA testing to challenge paternity by a putative father is only possible until the child is 2 After that it is too late.
BTW--the color of the child's skin--"getting darker in complexion" -- is not a reliable indicator. As you know, the child of a "white" person and a "black" person can range from "white" to very dark. Most Mexicans are part Mexican Indian and the same range of skin color is in play. The statement "getting darker in complexion" makes it seem the initial appearance was not decisive. If the hair is straight... the child is likely not yours. (Not politically correct for me to say. I know--but I think you know this to be pretty accurate.)
Bottom line, the birth certificate was open to challenge until the child was two years of age, now it is not.
Sign up to receive a 5-part series of useful information and advice about child custody law.