That does not make much sense, since I am the only one in my family, including all relatives are not lactose intolerant and I was raised on dairy for much of my life, until I realised that I was lactose intolerant and the cause for all of stomach problems I was having. It was one of the last things for me to think of, since it was not expected, due to my heritage, but yet here I am with the ability to digest lactose, s adaptation to dairy is not what it is about, but rather a random mutation. I would say that dairy use happens because of the mutation, not the other way around.