Quick answer
Biological connection and legal parentage are related but not interchangeable. A marriage presumption, acknowledgment, adoption, assisted-reproduction law, or court order may matter.
Do now
Gather the birth record, existing acknowledgments, marriage records, and prior orders. Ask the appropriate court or support agency which parentage process applies. Review an acknowledgment before signing; an informal home DNA result does not itself create or undo a court order.
Local note
NJ uses Family Part procedures; NY has parentage proceedings and orders of filiation; DC has its Parentage and Child Support Branch. Deadlines to challenge an acknowledgment can be short.
Official sources
NJ Courts — Initial FD application packet, NY Courts — Paternity, NY Courts — Order of Filiation, DC Courts — Parentage and Child Support Branch.