0 to 2 pt. Quality or Drawback
Your character is part of a magical family (so it's not just a clever
name). It could be anything from a long tradition of magical power to a
single magical relative who's willing to tutor the character.
The cost varies on who the relative is and how old the character is.
It's a free Quality for a character over the age of 18 as long as they have
at least 1 level of Sorcery. Such characters are expected to purchase their
own magic books (I.E., have your own Occult Library trait). For younger cast
members, it costs 1 pt. for most relatives, or 2 pts. for parents who are
magical. The only difference is that if the parents are simply trying to use
and control their magical child (Amy Madison, anyone?), it's actually a 2 pt.
Drawback.
The only significant limit to your character learning magic from
their family is that the character's parent or other relative will not give
them access to spells of Power Level four or higher until they have reached
maturity. Teenage cast members may consult their relation's two-point Occult
Library, but gaining access to any of these spells requires asking permission
(or sneaking behind someone's back).