User blog comment:Maki Kuronami/Lesson 28: Humanity did not receive a Grimm reminder/@comment-5717877-20141031014422/@comment-173.58.251.107-20141031015136

If there is a video or tweet from Monty explicitly saying "Hey, Raven is Yang's paternal twin sister who is a secretly raised apprentice of Qrow", I"ll believe it.