Why are age ratings for games harsher because of sex and nudity than because of violence and gore.

This really confuses me. Why can a game with zero violence and one brief sex scene be rated the same or more than a game where you kill 100s of innocent people, or are shown pictures of blody dismembered corpses?

When watching or playing a sex scene, I feel good, fine, maybe a little awkward at most. Sex is about love, having kids, sometimes lust, but it's a natural thing for humans. Nudity is the natural state of the human body, nothing weird about it.

While when watching or playing a scene with a lot of violence I feel repulsed, disgusted, It doesn't feel good. It's against everything ethics teach us. It really is a horrible thing. And games gloryfying it is even worse.

Why then is sex somehow worse for children than violence?