Shaykh Ahmad an-Najmee was asked the following question:

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”.

[Reference]

Translated by

Faisal Ibn Abdul Qaadir Ibn Hassan
Abu Sulaymaan