Board Thread:General Discussion/@comment-2003:80:8D08:D815:342B:C405:CE26:B2B9-20180125151950/@comment-4010415-20180125153738

This has actually been discussed here countless times, and the argument tends to boil down to this:

Against: Monty Oum stated that Ruby and Yang are half-sisters. The RWBY crew has never intentionally lied to the fandom, so if Monty said Ruby and Yang are half-sisters, then they're half-sisters. Ruby and Yang have two different mothers, so that means they share a father. As such, if Qrow is Ruby's father, then he has to be Yang's father as well, which means he had sex with his own sister. It's highly doubtful that CRWBY would have Yang be the product of incest, and besides, Yang looks a lot like Taiyang, and Monty said that Yang's eyes are purple because Tai's are blue and Raven's are red.

Ruby bonding with Qrow can easily be explained by the fact that Yang said Tai shut down after they lost Summer. So, if Tai was shut down and Summer and Raven weren't there, which adult is left to make an impression on young Ruby? Qrow.

For: They both wear red capes and wield scythes and are really strongly bonded with each other. Qrow wouldn't want to stay around in Ruby's life because of his Semblance. Writers of other shows lie all the time to protect plot twists.

(And I may have forgotten other arguments, but those are the ones I see most frequently.)