The Ruling on a New Muslim Giving Himself a Last Name If He is an Illegitmate Child- Shaikh Ahmad an-Najmi
Question: May Allah be good to you, this questioner from France says: there is a man who entered Islam and he does not have a father because his father and mother were not married [i.e. he is an illegitimate child]. So is it allowed for this Muslim to name himself the son of Adam or son of Ibrahim?
Answer: “It is allowed for him. He can name himself with any name”.
Faisal Ibn Abdul Qaadir Ibn Hassan