Board Thread:Hints and Tips by the Mizukage!/@comment-3030647-20150902231318/@comment-24384232-20150926184410

Hmmm I think I understand you're explanation though I could further expound on that using Chinese Medicine and a technique I created for my character Akemi Hyuga; the Eight Trigrams Imaginary Body Technique.

The idea is that elemental affinities are tied to the default ratio of yin and yang chakra in your body. This has further relations into say one's organs, and by that extension their genetics. Now we can go back to what defines an elemental affinity which is a predisposition to more easily mold one's chakra into an elemental form.

Together, along with your proposed theory would imply that not only must you have multiple elemental predispositions aka affinities, but the genetic mutation must also allow for them to be used simultaneously. That's the key, because molding one's chakra into one form is difficult enough but two at the same time would require extraordinary chakra control.

The genetic quirk however takes care of that. The arrangement of your yin-yang chakra ratio is such that you can mold both at the same time, and the simultaneous molding of both elements, generates a unique interaction between them that seemingly creates a new element or kekkai genkai.

Good stuff man.