And She Says It's Not My Baby

If you are not married to the mother of your child and paternity has not been established, you can file a petition with the court that you be declared the child(s) legal father. If you can afford one, you have the right to be represented by an attorney at any stage of a paternity trial. If the mother can afford one, the mother also has the right to be represented by an attorney at any stage of a paternity trial. You should begin by requesting a paternity test for the mother, the child, and yourself. If you request the tests, the court will order each of you to take one. If a court orders or the parties agree to paternity tests, the results of these tests will be a part of the paternity trial. If the court determines you are the legal father of the child, you will be responsible for child support. You will also have the right to request custody or visitation orders from the court. If you wish to spend time with your child, it is important that you make this request.

From the Texas Q and A Handbook for Non-Custodial Parents, Office of John Cornyn, Texas Attorney General