Board Thread:Theories and Speculation/@comment-27082825-20150116155842/@comment-24526205-20150120203202

I guess it Kekkei Tota is the joining of two Kekkei Genkai with a neutral element in common.

Jinton = Katon + Doton + Futon (Doton is neutral in relation to Katon and Futon)

In the Mei's case, she can't be Kekkei Tota, because not have a neutral element.