help me put this into words please

I know what you mean - as a baby I tended to dress mine (both boys) in white (easier to get stains out of), then as they got bigger, bright stuff - but not frills or dresses (there were some sparkles and leggings though). Mind you, I don't wear frills or dresses either, so whilst there's sure to be a huge dob of societal values, there's also some personal preference.

Mind you, I happily let my son wear pink stuff if he picks it now (youngest is 2 - wearing pink crocs as we speak), and my older one who still wears a nappy to bed (nearly 6) couldn't care less when those pullups are the pink ones (shops around here have a limited nappy supply in his size, so we take what we can get), and chose sparkly trainers for his last but one pair.

I think that's all you can really do as parents. You don't want to force them in either direction but you want to try and keep the unhealthy influences as balanced by good messages as possible - and you want them to just put whatever nappy you have on and not make a fuss!

I would say that the 'all infants in white dresses' phase - which wasn't so long ago - I have pictures of my dad who's in his 60s in a white dress - was more that all kids were lower value (I might hazard a guess that it's something to do with death in childhood being more common?) - whereas now we really dress our kids as mini-adults from the start (unless you're lazy like me and favour sleepsuits), so they get the hit of feminine/masculine much eariler

Also females do have a much wider range of socially acceptable clothes than males, so a girl wearing jeans, navy tops, dinosaurs etc may be more unusual but isn't frowned on like a boy in a dress could be.
I think there might also be something in that about homophobia - growing up gay as a boy can be perceived as a very negative thing whereas I think there's more of a tendency to think lesbians are going through a phase.

If we accept that as true, what about the period prior to the blue vs pink split, and when both genders where dressed the same, in dresses?

www.smithsonianmag.com/arts-culture/when-did-girls-start-wearing-pink-1370097/?no-ist

Were femininity and masculinity considered as equal prior to the late 20th century?