The real question is, what is it that you're so afraid of with gender/sexuality that you think it makes sense to show some expressions of it but not others? Sexual norms change regardless of what is officially considered normative and regardless of what is repressed, so you must know you're fighting a losing battle. So who or what is it exactly that you're fighting for? I think it has more to do with yourself than with children.

What is it about “sexual subcultures” that are inherently dangerous as opposed to the main culture that is inherently safe.

Is a book character being gay unsafe for kids in a way that the same character being straight is not?

Sounds more like YOU are not ready to handle it, and don’t want to have that discussion (at an age appropriate level) with them. Which is fine. Just don’t give us the BS excuse that your child is too dumb to think critically. Kids are smarter than you give them credit for.

If a pre-teen can understand the concept of sex, what’s so difficult about explaining that _some_ people have non-mainstream sexual attraction?

A better example is restricting access to actually dangerous ideas, like “Mein Kampf”.

I’ve read the first chapters of Mein Kampf, because i was very curious why the book is forbidden knowledge. It was actually quite easy to download it. I did not like the book at all, but the search to get it was quite exciting. Same with the weirdly Hackers Cookbook. Same with a lot of other so-called dangerous knowledge. I have also seen awful things on the internet that made me physically sick. I have also seen hacks that were so easy i wondered why big huge companies had not thought of that. Point is that restricting will not stop curious kids to search for it and find it. It all taught me to also accept my kids as extremely curious human beings who may not align with your personal points of view and that can sometimes be ok as long as you keep communicating with each other respectfully. Tell them why you think Mein Kampf is bad. Show them things like experiments on MythBusters if they have questions.

Seemed simple to me: one of the first results for "Mein Kampf full text" gave me https://gutenberg.net.au/ebooks02/0200601h.html

But yeah, I don't want to be expressly forbidding disagreeable content to my kids, I want them to learn to choose content that is worthwhile themselves.

oh i don’t think any of it should be restricted personally. I was just pointing out that IF we are going to humor that argument at all, i’d rather restrict more dangerous ideas and things. But it’s a slippery slope!

Teaching minors about sex is a serious criminal offence?

If telling your children that gay people exist is a crime where you live, maybe the problem is with the laws in your place of residence.

Pre-teens don't understand sex, which is what I said, and which is why they cannot consent to it.

Pre-teens can understand sex just like they can understand what a contract is or that alcohol exists. We don't allow them to participate in those things but they can certainly be aware of its existence.

They do understand sex, but don't take the consequences seriously enough (like STDs or kids at such a young age) — they are still in the exploration phase where they believe they are invincible and nothing bad can happen to them.

well sure, they won’t understand sex if nobody every explained it to them. Learning through osmosis isn’t possible. :) They are definitely capable of understanding how a baby is made if you get a textbook and show them.

Whether or not they should learn that as a pre-teen is certainly up for debate, and many people / cultures have different opinions on that.

They may be ready that's why they are looking but you might not be.