Mages can take feral upbringing. HoH:MC says, in the sidebar on page 37, that it used to be common in House Bjornaer, but that it isn't so much now as they are trying to escape their reputation.
The problem I have with "Apprenticed from the Wilds" is that it wouldn't count against the Personality Flaw limit.
In any case, outside of any mechanical effects you can and should consider it in the same way as Faerie and Sheltered Upbringing as to what kind of reactions are expected from the character.