Aasimar

Sometimes, a child is born with a divine spark. Innumerable variables in a Mortal's birth can create an aasimar, not limited to divine heritage, phase of the moons, proximity to leylines, proximity to a god's Avatar, to name a few.
Signs of this show as the children come of age, when the magical characteristics of an aasimar begin to manifest. There are many types of aasimar, influenced by the very same variables that made the circumstances of their birth incredible. A child born under a full Faustus during a thunderstorm might bear wings of terrible darkness, or the child of a priest of the Muse might be able to channel pure arcane power through their body.