Deuteronomy 22:28-29

[robvalue]

I'm of the opinion that many people just go along with what the norm is. They get taught how their society works, and they absorb what they are taught. It takes a strong mind to question the very basics. It's always a lot less effort to go with the flow.

So once the overall position changes, then new generations grow up with it, and it becomes "obvious". But getting society to make that change is far from easy.