One does not "become lactose tolerant," humans are born lactose tolerant, after all their primary food for the first few months of life is milk. A lactose intol

One does not "become lactose tolerant," humans are born lactose tolerant, after all their primary food for the first few months of life is milk. A lactose intolerant baby is very rare. Lactose intolerance happens with age in X% of the population. The ones who don't become lactose intolerance simply retain their lactase production that they've always have had.