My cousin's mother in law told his son and a friend (they are 4 or 5) that they can't hug. That guys…

My cousin's mother in law told his son and a friend (they are 4 or 5) that they can't hug. That guys don't hug. That they have to shake hands or fist bump. WTF?! I will never tell my son's that they can't hug. My kids are gonna be allowed to show feelings and greet people how they want to in a respectful manner.