Approximately 65% of the worlds population suffers from a diminished ability to digest dairy after childhood, see http://ghr.nlm.nih.gov/condition/lactose-intol

Approximately 65% of the worlds population suffers from a diminished ability to digest dairy after childhood, see http://ghr.nlm.nih.gov/condition/lactose-intolerance http://ghr.nlm.nih.gov/condition/lactose-intolerance. That said lactose intolerance usually doesn't occur in people of European descent so I would imagine you happen to live in s special subgroup who has no such problem.