Board Thread:Off Topic/@comment-33408428-20171018211756/@comment-4010415-20171018213156

Monty said that Ruby and Yang are half-sisters, so the only way for them to be half-sisters with different moms is for them to have the same dad, which would mean Qrow would also have to be Yang's dad, which would mean he had sex with his sister.

As for why Ruby is more closely bonded with Qrow than Tai, remember what Yang said in Volume 2: Tai shut down after they lost Summer. Ruby and Yang were still children when that happened, and Ruby was pretty young. Imagine being a little kid, living in a house with only your older sister and your dad, and your dad is completely shut down with depression, barely functioning, barely being a parent. But your uncle stops by once in a while, makes sure you guys are okay, makes sure you and your sister have food to eat, spends time with you and your sister, and he's a pretty cool and fun guy. Of course you're gonna bond more with your cool uncle than your depressed dad who just lays around all day.