In Illinois, a man is a child's legal father only if one of the following is true:
* He was married to the child's mother when the child was born or when the child was conceived (or both)
* He married the mother after the child's birth and he is listed with his permission (as of August 9, 1996, his written permission is needed) on the child's birth certificate
* There is a court order or Department of Public Aid administrative order of paternity
* He and the mother have signed a "Voluntary Acknowledgement of Parentage" or "Voluntary Acknowledgement of Paternity" form