User blog comment:Uraharattack/Guys, I need your opinion on my theory./@comment-25247258-20141208053416

I like this theory, but I don't quite know if it adds up. He's from a "lower class aristocratic family" which probably has quite a bit of attention from the higher-ups in soul society, and it is fairly well established that being a Quincy is hereditary (with the exception of Quincies that Yhwach created himself like the Arrancar and presumably the original Quincies). We don't exactly know how families in Soul Society work, but It is implied that, unless they are adopted (which as we know from Rukia's case is frowned upon), people in such families are born in Soul Society. The only way I could see Ukitake being a Quincy is if he or one of his parents was made a Quincy by Yhwach; if he was made a Quincy by Yhwach then I doubt Yamamoto would have allowed him to become or remain a Shinigami (he would probably know about that), and one of his parents being a Quincy pushes back our timeline even more.

We also have to take into account that according to the article here for the Shin'ō Academy, it was founded 2100 years ago, and Shunsui and Ukitake were the first graduates that became captains, I find it a bit unlikely that they would have graduated or attended the academy after the first war with the Quincies 1000 years ago, although I guess the Quincies could have existed for a very long time before that. We also didn't see any drama with Ukitake when the invasion started (nothing about him having to "pick a side"). At this point the only way I could see him being a Quincy is if nobody except Yhwach and maybe some other Quincies knew about it (including Ukitake himself)