When creating a magus, I always do the parens also, and on one occasion his parens too (in that case, all the way back to Merinita, who I left ambiguous.) I don't stat any of the parens, but could have. In some cases, my parens writeups become more interesting than the main character himself, which is perhaps how it should be since they've already done stuff and been done to.
BTW, is Hectic Practices a new hedge virtue, even better than mere fast casting?
EDIT: Not always: My ancient, Penultimate Twilight Tremere "The Diedne are Coming" magus didn't get a parens. No one remembers him anyway.