User blog comment:Zebul/NARUTO YIN-YANG RELEASE/@comment-4080775-20170203155055/@comment-10452902-20170204105516

I should also point out that it has never been stated to be a Kekkei Genkai and therefore, your logic that you are either born with it or you are not is pretty much invalid. The conditions for using Yin-Yang was never explained in the anime or manga and nor were Yin or Yang Release. My guess is it is based on intelligence rather than blood which is why the really smart people like Sakura, Shikamaru and Ino can use one or the other though whether or not they can use the other but simple choose not to is impossible to argue with our lack of information. As for Yin-Yang Release, perhaps it requires someone to be exceptionally intelligent, a true genius as being a prodigy and being a genius are not exactly interchangeable as demonstrated by Lee and Gai who are Taijutsu prodigies but not exactly the the sharpest knife in the drawer and even Naruto who is a prodigy in the use of Shadow Clones and the transformation technique.