My friend is the father of a USC child who just turned 21 years old. The father is not married to the child's mother though both the mother and father are living together. Thus, the USC child is an illegitimate child of the father. The question he asks is if he can be petitioned by his USC child as parent and be eligible to adjust status. The instructions for I-130 petition form requires that the birth certificate of the child and the marriage certificate of the father be included in the petition.