Title: Why are some people lactose intolerant? - Quora
Headings: Why are some people lactose intolerant?
Why are some people lactose intolerant?
Anonymous

Content: So, then, most humans are lactose intolerant because for most of human history, they had no reason not to be. When conditions changed, we started moving in the direction of not being lactose intolerant, but evolution is slow and the advantage is slight, so only about a third of us aren’t lactose intolerant now. Prabha Karan
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Answered 2 years ago · Author has 403 answers and 646.9K answer views
Originally Answered: How can someone become lactose intolerant all of a sudden? There are so many reasons for it, not a single reason. 1)Body nature changes with age,environment,food habits,diseases,medicines took for those diseases. So when the body nature changes it would change the digestion also. This can lead to lactose intolerance. 2)Some persons really won’t be capable of digesting milk after they attained adulthood. This is not new.