Source of most (if not all) Kekkei Genkai

[6ari8]

No you don't just need the DNA. You can get it through a tailed beast as well. Or you can use a forbidden scroll to perform kkg. It's not limited to DNA alone. Besides, the affinity is part of your chakra. It's about 500-1000 years since the so6p came, and since then people discovered their nature affinity. It might as well be a natural occurrence. People found way to develop it. Just like they found ways to develop ninjutsu. Having 2 natures can create different things, though it isn't kkg, it's still pretty close. Besides it isn't just DNA that gives the affinity. Hashirama seems to be the only one that naturally developed mokuton within his family.

you seem like you're agreeing without knowing it. I said you need the DNA to HAVE the capacity to DEVELOP it. Getting it through a tailed beast is a different matter. One's chakra stems from the DNA as well. Hashirama, as I said, had the greatest potential in his DNA to unlock it, just like some Uchiha can unlock the Sharingan and some cannot eventhough they're from the same clan. I think it's because they didn't get the capacity to unlock it within them. KG when it comes to nature manipulation means to use two different elements at the same time to create a new element. It doesn't matter if you have the two natures required to produce the new element if you don't have the capacity in your DNA to do so. Hashirama and other KG users like Haku had the capacity so they were able to while others who have the two elements needed but were unable to produce the KG element.

 

[6ari8]

I think I was pretty much right here...

 

[Seventh Sama]

I think I was pretty much right here...

Except the part where they're Rikudou's descendants..