@AI78: Reminds me of back in the late 1990s. There was a groundbreaking study where researchers learned after decades of interviews and review of sociological and psychological data from all over the place that...
*get ready*
...
Children can be incredibly cruel to one another, and girls in particular can be exceptionally so, especially a la passive-aggression. And boys can be exceptionally physically violent, especially towards other, smaller boys.
*I know! Crazy, right? Unheard of!*