If the mother is married to someone other than the biological father at the time of the child's birth or the baby is born within 300 days of her divorce from a man who is not the biological father, that man is the presumed father.
The biological father cannot become the legal father by signing the Acknowledgement Of Paternity Form until a presumed father, if any, signs the Denial of Paternity Form, which is part of the Acknowledgement Of Paternity Form.
If the Denial is not signed, either biological parent can open a case with the Attorney General or establish paternity through the courts.
However, most legal remedies become unavailable upon the minor child becoming an adult.
Retroactive Child Support -