Board Thread:Episode Discussion/@comment-24573226-20171012080158/@comment-27312496-20171014195529

LucasVerBeek wrote: Who's to say Qrow or Yang didn't tell them at some point, I mean Weiss i think told them about Blake being a Faunus

It could have come up in a conversation with either Yang or Ruby with any of there friends. It kind of shows that Raven isn't some big secret that their family hides. Sure it may be a little sensitive issue but not enough that they never talk about it.