User blog comment:Theory of everything/Grimm Speculations Part Six: The Grimm Family Tree/@comment-5189167-20120823085825/@comment-5189167-20120823205256

Well, on Renard's talk page, there's a link to an interview where Renard confirms he's half-Hexenbiest. Everything else is what i implied. From just the canon, there's barely enough information to make a legitimate theory, and the interview with Renard is, in my opinion, a good resource.