Board Thread:Episode Discussions/@comment-1181222-20180131111324/@comment-734582-20180131201331

Harpermorgz wrote: Looking at "Release" pages, it mentions that several of Release users have different forms of of that release. I.e. Mei uses Acidic Mud, while Kurotsuchi uses ashes and quicklime for Lava Release. So it's very possible that different variations of the Release is what makes it a kekkei genkai. Lava release is lava release. Sure it can be used in different ways, but so can other elements. Lighting is sometimes just electricity, sometimes a tangible thing. Fire can be fire, but also ash. Earth can be dirt, rock, mud.

Kekkei Genkai are genetic. They are not necessarily linked to a clan, though often clans are the ones that can really maintain the genes. The Uchiha clan is an example of a clan that managed to keep it's Sharingan within it's own bloodline, same for Ice Release and Haku's clan. others, like Lava Release, not so much.

Boil Release, Byakugan, Explosion Release, Ice release, Jugo's KKG, Sharingan, Scorch Release, Shikotsumyaku, and Wood Release are all examples of heavily limited KKG, in some cases to clans and in some cases to a select few individuals. So it's likely that such KKG are either hoarded by clans, or the clans that hoarded them were destroyed/absorbed.

Lava and Magnet Release are the only elemental KKG that really stand out as being spread out among several villages and unrelated people, making it more likely that if they were once hoarded by clans, those clans were destroyed. Mei for instance is from a place where KKG users were hated, so spreading of KKG is much more common there, whereas the Hidden Stone seemed very light on it's Clan Influence, making genetic mixing more likely.