Board Thread:Speculation House/@comment-24.247.91.107-20140511154823/@comment-73.42.187.52-20150112004140

^Both Yang and Ruby stated Qrow was their uncle, there is no "likely" about it.

However a relation to Taiyang is a stretch, people refer to unrelated people as uncle if they are raised with them as their uncle, so Taiyang, or either mom could be Qrow's sibling(because just as they didn't tell Yang that 1 parent wasn't her mommy you aren't going to tell toddler's that one has an uncle and the other doesn't, as long as Qrow cared for both as an uncle he is an uncle.

or his team could have been really tight, and they could refer to him as uncle because he is their parents brother-in arms.