Couples are having children outside of marriage more and more often. These changing demographics place new strains on the judicial system as it tries to cope with this phenomenon. Traditionally, most parental rights are established based upon marriage. If a child was born to a married couple, it was presumed to be the progeny of both parents. The burden was on the married father to prove he wasn't the father. Similarly, if a man other than the married father claims to be the father ? he would also have a serious legal burden to overcome.
Barring that traditional course, the other most common method of establishing parental rights is in the hospital when the child is born. Most hospitals will provide the parents with a parental affirmation form which will include the mother's and child's name and allow the father to fill it out. It is also possible for the parents to submit this form to the appropriate court or state agency after the child's birth.
If you are unmarried and trying to get custodial rights over your child then you may want to speak to an attorney. Generally, you cannot get custodial rights over a child unless you can get some form of legal acknowledgment that you are the child's father. If this never occurred while the child was born or during the child's early life, then you may need the assistance of an attorney to help you file the paperwork to enforce your rights. Don't try do it alone, you don't want to risk your custodial and parental rights because the paperwork was filed incorrectly.