The show focuses on his journey to master the elements and restore balance to the world, with his primary focus being on saving the world from the Fire Nation. He never marries or has children within the series.
The show's sequel, "The Legend of Korra," features Aang's son, Tenzin, who is a prominent figure in the new generation of airbenders. However, Tenzin is Aang's *eldest* child, not the youngest.