Given the show’s lack of cloning technology or other means of immaculate conception, it can be said with almost 100% certainty that Aang had a biological mother and father — they just may have not been a familial mother and father. Aang is a member of the Air Nomad tribe, a community of monks who lived in the four Air Temples (north, south, east, and west). Asnotes, “Avatar” and its sequels were loosely inspired by different historical cultures throughout the continent of Asia.
The Air Nomads were primarily inspired by Tibetan monks, who in reality would take a vow of celibacy upon joining the religion (via). This creates a bit of a conundrum for the show and how its rules work. Though at first glance it appears as though the Air Nomads are chaste, the ultimate answer is far more complicated and rooted in the show’s mystical lore — the only way Aang could have his awesome, terrifying powers is through his biological parents.