Why Men can be shirtless and women can not in public

I wanted to know why men can be shirtless if they want to and women have to keep cover it's because women have breast and That is why people make bras for women because their breast start sagging and it does not look nice.

Lets say if women run or jump up and down when they shirtless the breast will started bouncing and it will hurt any woman but men do not have to worry they do not have breast so if men run or jump there chest will not bounce or sag.

The Bra supports the breasts. Men have nibbles because it has to do with how humans develop in the wombn that is what Ian Tattersall had said he is a paleoanthropologist at the American Museum of Natural History in New York City.

And also men where girls when they where in in the mothers stomach then the Y chromosome starts to kick in that that is how they are made males.

If your a female you have 2 x's Chromosome and if you are a male you have a x and a y chromosome.