Malbar and Beyond
The Aasimar are not so much a race as a bloodline. They are always human, but possess some form of celestial blood in them. Through heredity or blessing, they manifest in certain generations as children and are often kept hidden by their families. In days long past, the Aasimar were revered but they now are often swept away to temples against the will of their parents so they are kept hidden for years until they are old enough to travel out on their own. As a result, most are often very reclusive and shy and rarely interact with others. Finding an Aasimar that is social and open is probably a sign that they were swept away to a temple and raised up there and have no knowledge of the troubles other Aasimar deal with.