Board Thread:Theories and Speculation/@comment-1872728-20151008094957/@comment-734582-20151009164623

GreatestSin wrote: isnt it stated that wood releae is water+earth? That does not confirm or deny the possibility that it's origins are different. Mangekyou is just genjutsu yet it's origins are different. Amaterasu is Ninjutsu but it's origins are different.

Wood Release seems to work different from any other release, including it's natural affinity for Tailed Beasts. So it's not weird that it's origins may be different too.