Board Thread:Off Topic/@comment-28745050-20160614060931/@comment-26397825-20160727221514

Monty was talking about another theory at the time. He specifically said that Yang is Ruby's blood-related half sister in response to that theory. It had nothing to do with Ruby's parentage, so he would have no reason to lie about that.

We know for a fact that Taiyang and Raven are Yang's parents. Going off this, we know for a fact that Taiyang must be Ruby's father because Summer is her mother. Monty told us outright in a response to a theory that had nothing to do with Ruby's father and entirely to do with who Summer is, when he had no reason to lie or misguide us, as he could have just left it at "no Yang is not Summer". He didn't have to even mention a relation between Yang and Ruby.

But he did. He was giving extra information that he didn't have to, there was no need for any deception (which again, they just don't do), and that information was that Ruby and Yang are blood-related half sisters. This makes Taiyang her father, Summer and her mother, and Qrow her step-uncle.