This is just madness to me, and absolutely agree with a pp who says this reeks of being decided by people who have no experience of children.
Personally I've had a daughter who was clearly what we would have called a 'tomboy' from age 3. Wanted short hair. Wanted blue clothes. I indulged her. Wanted to be a boy BECAUSE CHASE FROM PAW PATROL IS A BOY.
That's where I explained no dear, Chase is a dog.
She's 7 now and still likes a lot of typical "boy" things and has mostly boy friends, she has hair down to her bum, pink dresses etc.
I gives me chills thinking what would have happened if the nursery had picked up on this and gone behind my back to tell her she could be a boy.
Both of my 'tomboy' friends at school are women. One of them a lesbian.
I have a brother who is very effeminate (whatever that means) and always has been. He's a gay man. He's happy.
What made him unhappy in school wasn't being called a boy, it was that loads of people called him a poof.
Maybe they could deal with bullying in schools - which is rife in my experience. Both of my daughters have had it. One of them dragged onto the ground and strangled in primary school.
That's a bit more difficult than indulging 4 year olds who say they identify as dogs though, eh?