None.. ok.. almost none of us are human.. Angelic, Demonic, Dragon, Gryphon, Fae, Elven, shifter, and not a frapping clue what else.. think if we really pushed like 1% of us count as human.. maybe..

Switching.. is usually fairly easy.. especially if we're working on something.. and then the viewpoint will change and just have to do a double take and figure out we shifted.. if we fight it.. or something harmful causes us to switch.. then it could be bad.. but usually it's fairly easy.