To be fair in my experience kids reactions seem to be much more based on other kids a lot of the time anyway and there's only so much you can do. My daughter went from being totally accepting that men could be with men when she was 4 or 5 (we have gay friends and she thought nothing of it), to a worrying little homophobe when she was 6/7, and now she's 9 and can actually understand concepts like romantic relationships and sexuality and is back to thinking nothing of it.
I think maybe there are more fundamental considerations when it comes to understanding why younger kids are confused. They don't really have any concept of love or attraction and their basic concept of what "a couple" is, is "a mummy and a daddy" ... like, people are together SPECIFICALLY for that reason, I honestly don't think they necessarily even get that it's a separate relationship that goes beyond being "the parents". Which I guess contributes to confusion about why two men or two women would be in a relationship. So in theory, the perfect time to be talking about homosexuality being normal would be around the age of 8 when they're starting to develop a concept of what romantic relationships are
at all.
I'm not saying there's any harm normalising it for younger kids too I'm just not totally convinced that there's much point or that it makes much difference. They find heterosexual relationships weird and hilarious too
