violinmana said:
Most likely mixing his entire life.
One might even argue that this might have something to do with Narutos abnormal chakra levels. I mean those two "ate" Kyuubis chakra, got whiskers and even though they did not have the actual Kyuubi sealed inside of them, they were known to possess humongous chakra levels. They were also said to be descendants of the original Sage of the Six Paths, just like Naruto.
Naruto could have "eaten" Kyuubis chakra through the connections between mother and child since Kushina had Kyuubi sealed in her. For all we know, Naruto might have had access to small amounts of Kyuubis chakra like the two brothers did, even if the actual Kyuubi had never been sealed into him.