and everyone knew it.

That fact doesn't excuse Polanski of anything. All it means is that the mother should have been brought up on charges of child abuse and endangerment.

The only consent that counts is that of the person who had the sex. But your argument raises an interesting question: Is there a connection between (a) the notion that parents have the authority to grant or withhold consent on behalf of their teenagers and (b) a predator's notion that he doesn't need the teen's consent if he has her mom's?

Even if true, it's irrelevant. He raped her. In my neck of the woods, he'd have been gelded with a rusty knife, and left to tend to himself.