Sexuality being involved somehow changes things

You can write a story where a sibling kills or abuses their sibling without explicitly condemning that

And that’s a story that simply depicts that

You can write a story where two siblings have an incestous relationship without explicitly condemning that

And suddenly that’s immoral to write and read

I’m sure that we can all agree that incest, murder, abuse etc. Are all bad

Yet only when it’s something sexual does it suddenly say something about the writers/readers of fiction

That is not to say this phenomenon doesn’t exist outside of sexuality

Some people believe that violent video games cause violence

But it’s orders of magnitude more prevalent

Why