Class is product of physical size & strength combined with mental acuity. The Normans who conquered England were bigger, stronger and smarter. They took what they wanted, screwed who they liked, and established control systems to make sure no one could challenge their authority.
It has always been this way. It's why the lower classes are small, ugly and stupid.
Yeah, everyone knows how strong and smart royalty has historically been. And how aristocrats are always better human specimens than peasants.