How old do you have to be to grow a mustache?

I’ve recently decide to experiment with facial hair and have come to the conclusion that a man under 40 should definitely have hair on his chin to accompany his stache. Imagine any number of guys you know under 40 with just a mustache. Odds are you are imagining a group of guys that all look like perverts.

We all know guys with mustaches, but odds are they are least 50. So, when do you stop looking like Kip and start looking like Tom Selleck?