I have a birth certificate of the late 1920s of a child John X born to Mary X and David Y. It has "adopted" on the right hand side of the certificate. Both parents were present at the registration, which took place about six weeks after the birth. They were not married and did not subsequently marry. It is thought that John may have been Mary's child. There is no other birth certificate for him that I can find.

Does anyone know, is it likely that this adoption was in order for David to have legal responsilility, willingly taken, as father of this baby? Or is it more likely this was an adoption of an unrelated child by 2 unmarried people?