User blog comment:Derrmann/By Jove, I've got it! (Totally know why Ruby and Yang have different last names)/@comment-76.78.234.122-20131116063739

Since Monty has said that Ruby and Yang are not cousins, sisters, or step-sisters, I think that Yang is rwby's aunt. So yang is Summer Rose's baby sister and probably Qrow's baby sister. That also mean she was raised by her grandmother and grandfather which makes sense because Little red Riding hood was close to her grandmother.