I don’t think it’s always as blatant as bullying, but young children around Reception age definitely go through a spell of ‘gender policing’ as it were. I’ve taught children whose own mothers were doctors who would furiously insist in the role play area that girls are nurses and boys are doctors and that’s that. Lots of discussion about what is a boy’s/ girl’s colour and the same boys who spent most of the nursery year happily dressed as Minnie Mouse or Elsa suddenly get very militant about what constitutes boys or girls clothing.
Of course it’s just a phase and them figuring things out, and of course you want to challenge these stereotypes and point out that anyone can drink from the pink cup, like dinosaurs, play fairies or wear gingham shorts - sometimes all at the same time.
With my own DD, I have to admit to feeling a bit heartbroken when she insists on wearing the pinafore option rather than the comfy stretchy trousers otherwise she will ‘look like a boy’, and I’m bloody fed up with the impractical pale yellow gingham dresses and once worn forever ruined white knee socks. But she’s one of the youngest in her Reception year and already navigating so much, I feel like forcing her to blaze a trail for gender equality is probably a bridge too far. I still talk about how girls can wear trousers and boys can have long hair etc, pointing out examples and trying to offer diverse interests and role models. But right now she wants and needs to fit in so we’ll go with that for the time being. Plus, as insistent as my DD is, it’s still somehow more socially acceptable for girls to wear the same as the boys, than for boys to wear what’s perceived as the ‘girls’ option. Which is all kinds of wrong, and if I had a boy who was really keen to go against the norm I hope I’d support and encourage him in that - but I wouldn’t want to have him navigate all the above just because I thought it looked nicer of that was how it ‘should’ be.