Interestingly in Australia it’s become the norm for kids of all genders to wear full sleeve rash tops that cover their chests, shoulders and arms. This is because our sun is so damaging and people now are educated about how much of the sun damage that can lead to skin cancers is caused by sun exposure from childhood.
The great thing about this movement is that now we see all kids and also many adults all wearing similar swim attire and it’s almost become strange to see a kid playing in the water with their chests bare.
In regards to bikinis on babies, what a stupid thing for anyone to consider putting on their kid! I’m sure if I tried to put a string bikini on any of my kids as babies they would have ripped them off immediately!