Is there logic behind not being allowed to pierce my body (ears too)?
Yes. Technically speaking YOU don’t HAVE a body. That body is the property of your mother and father. The reason why they provide food, shelter and other necessities is because they love you and they’re LEGALLY obligated to. Part of the legal obligation includes making sure YOU don’t damage THEIR property. Now when you’re legally declared an adult the body becomes YOURS. At THAT point you can put as many little holes in it you damn well please.