But I didn't know it happened with age
Of course it is with age. No mammals are born lactose intolerant. We drink milk as infants.
Almost universally, all adult mammals become lactose intolerant. We humans are lucky for those of us who tolerant.
Sure, but I figured that lactose intolerance would typically manifest before the age of, say, 20. I didn't realize that people could become lactose intolerant as seniors.
But I didn't know it happened with age
Of course it is with age. No mammals are born lactose intolerant. We drink milk as infants.
Almost universally, all adult mammals become lactose intolerant. We humans are lucky for those of us who tolerant.
Sure, but I figured that lactose intolerance would typically manifest before the age of, say, 20. I didn't realize that people could become lactose intolerant as seniors.