Because he has no other family whatsoever to speak of. Since he was born and named Exsul, which means "Exile", he was treated as an outcast and looked down on by his tribe. And he doesnt remember his mothers touch or how it felt to be in her arms, the way i worded it said that what he regrets is that he not only had that feeling taken from him, but he was denied the ability to ever feel it at all. His mother had told her tribe what happened to her, looking for compassion of sorts, but none was given to her. They viewed her, and her unborn child at the time, as a manifestation of abomination.
If u have any other questions, feel free to ask.