I’m not sure though, i didn’t research. Correct me if my sources are wrong so i could kill them....Ofcourse im kidding---not >:p

Japanese use that annoying kawaii (cute) face during world war so that soldiers will not kill them. "Too cute and too innocent" or the " doll like" look can spare them from their death. Hence, the peace sign and cute smile that is now commonly used when taking selfies.