I think I only ever came across one overt discriminator, an elderly music teacher in primary who took an instant dislike to one lad, sent him to the rear, and encouraged him to play up just so she could punish him. Character-building, I think she called it. Fortunately she retired after a year or she might have ended up murdered, the lad had a real shrunken head from his dad's days in the Diplomatic Service in Borneo.