Does Sora and cloud are brothers?

Sora and Riku both look the same and so do Schwi and Shiro so that brings me to believe that Sora and Shiro are actually Riku and Schwi but reincarnated with all of there memories from who they were in the past lost.

By the way I haven’t read any of the light novels i’ve only watched the series and the film so this is just a theory that I have come up with and none of this is based off of facts from the light novel or the series and film.