Board Thread:Naruto Discussions/@comment-3279282-20140413164418/@comment-4912646-20140414004227

Besides Kishimoto just not caring about consistency with natures (remember everyone suddenly using Earth Release?), there is a possible explanation for how Obito (and now potentially Naruto) could suddenly use advanced natures without first learning to use the two component natures. Yamato never said you have to actually master Water and Earth to combine them. For all we know, creating Wood chakra could take only the bare minimum skill in creating water/earth chakra, so it could be done without undergoing the training for those natures. Just because Obito could suddenly use Wood after getting his artificial body, doesn't mean he could suddenly use Earth or Water as well, since regular natures aren't genetically exclusive (as Hiruzen proved). That said, Obito likely did gain a sort of affinity for them, and we know he did eventually learn to use Earth Release by adulthood.