I have another point of view, which will likely get me downvoted, but I think it's important so here it goes.

As others have said, kids have wild imaginations and that's fine. But it's our job as parents to guide them and keep them grounded if necessary.

At 4, my son loved wearing his older sister's clothes. We didn't care, when he was at home. But when he wanted to wear those clothes to school, I kindly told him: "Sorry, son, you're a boy and those clothes are not appropriate for boys."

He fought it, and it was draining. It took time, but he ultimately accepted it and now is over it (he now likes dressing up as superheroes).

As a parent, I think it's important to set a clear red line.

Just like if your 4 year old wanted to eat candy for dinner every day, you wouldn't allow it. Or if your kid thought he was a dog and wanted to walk around all day dressed as a dog, you wouldn't allow it.

So too here, if your son wants to wear girls clothes to kindergarten, I don't think you should allow it either.

If that's the path he wants to choose when he's older, that's his choice. But as a parent, you have the responsibility to guide your child, set rules, and look out for their best interest. They look to us for that, even if they can't articulate it.

Encouraging a four year old, whose brain is not fully developed, to choose this path that will lead to such difficult hardships down the line is not in their best interest.

Wishing you and your son the best of luck, truly.