OK to be...lactose free!

I'm taking a holistic health practitioner class and this is one little nugget of info we got in class that I thought was interesting.
People lose the enzyme that digests at 18 months. It's natures way of getting babies to rely on food instead of mothers milk. So, people who are lactose intolerant are NORMAL. We're not supposed to be able to digest milk, we don't have the enzymes for it. And people who have no problems with milk are those that have MUTATED over time because their ancestors were probably exposed to so much dairy that their bodies adapted.
So all you milk drinkers are WEIRD!