Legal Question in Family Law in Texas

If he didn't sign an Acknowledgment of Paternity or get adjudicated the father, I think you may have to find a living relative of his and ask a court to order genetic testing, which even if just done say on his brother instead of him would still show pretty accurately whether he was likely to have been the father, and very accurately if another child of his was tested. It's possible that if he lived with you and your daughter for at least two years after she was born there might be a presumption that he was her father (that's enough to give him some rights in a Texas family case), but I think they'll probably require more proof than that. It seems like Social Security has a fairly comprehensive website, so you might try looking there.