A reflection about the traditions and divisions between boy and girl's clothing. Why can't we dress as we like?

Leo loves to wear costumes: pirate, superhero, knight... he also likes to put on a lavender skirt, but the day he decided to go out with it, someone mistakes him for a girl. He gets very angry. Can't a boy play and put on a skirt? Years ago, girls weren ́t allowed to wear pants...