Nail polish on boys?

So a FB friend shared the post below & said she wouldn’t let her son wear nail polish because “it’s for girls.”

My question to CC: Is nail polish only for women? Would you let your male child to wear nail polish?

To those who said 1yes or 2no: Why? How would you explain they can’t? If you catch them painting their nails secretly would you punish them?

Bonus: When are kids sure about their gender? When do they stop being confused?

I added the other comments so y’all can see the other’s logics. I wanted to comment to the rest of the women but didn’t want to continue to stir the pot lol.