Board Thread:Theories and Speculation/@comment-27295021-20180308000450/@comment-4974066-20180308002558

If you're asking is it possible for an elderly skilled ninja to use all 5 basic natures through training throughout their youth, the answer is yes. There are a number of examples of characters who did just that such as Orochimaru, Hashirama, Tobirama, Madara and Hiruzen. But if you're asking if it's possible for an elderly skilled ninja who has all 5 basic natures to use kekkei genkai (such as lava release) by combining different natures through nothing but sheer practice, the answer is no. A ninja can use 2 natures simultaneously, however only through a kekkei genkai can they produce an alternate nature like wood/lava/magnet because there genetic makeup allows for them produce that effect. There is only 1 instance that I know of where a person was able to seemingly 'learn' a kekkei genkai, Gaara's father Rasa. Iirc, the 4th databook says that Rasa was about to use magnet release by studying the Kazekage before him. But a person like him should be seen as a huge exception and not the norm.