If anybody is interested there’s a very good thesis by McKeon on “The emergence of gender difference” in the 17th and 18th centuries.
Before that childhood as a recognised stage did not exist and there was only Infancy and Adulthood. Infants, boy or girl, were treated the same, mostly till around their 7th birthday when they were breached or corseted. If you look at paintings it’s impossible to tell whether the very young children in the family are boys or girls. They are all in “petticoats”.
Personally, having spent my working life with children aged 2 to 7, I would say that any concept of gender comes from outside influences in the early years.
Watching young children develop their thinking is fascinating, not least because of the erroneous (but logical) conclusions they reach.
A girl with an older brother will often think that she will grow a penis as she gets older, just as she will grow taller. Sometimes that she will turn into a boy.
A boy with female siblings will think and sometimes be anxious that his penis will disappear.
A little girl with a baby brother thought there was something badly wrong with him because of his “growths” and her experience of a grandparent with a facial cancer.
Some children declared they were different genders on different days, depending on what they felt like.
I have had “dogs” and “sheep” in my room too.
I think early childhood is all about exploring the world and their place in it. It’s a fluid, puzzling time. I don’t like to see children forced into their birth gender mode by parents with limited expectations of what boys and girls are and do.
But equally I think it would be an enormous mistake to place a change of gender on a young child who is probably only experimenting and exploring the concept f gender or, indeed, what it is to be human.
I think we are jumping too soon in regard to young children.