@Firkle there's no real age limit, but just keep in mind most are college age, as most characters attend Reinforce, though we do have a few that are older as town folk.
There are a few characters that are up for adoption as well (see wanted hider on the first page and the teacher list in the character tab).
Also, to everyone, just remember if you have a character you would like to put a character up for adoption, just let me know and post up something like you see in the wanted tab.