I didn't develop intolerance until my late 40s (of milk, that is). Acidophilis doesn't help; I think even makes it worse for me, but the lactase tablets most certainly do. There are actually web sites that help people deal with acidophilis intolerance.
Your example is exactly the kind of information that is supposed to make real scientists remember that simple corellation is not causation.
I would bet that you could take a group of children from the predominately lactose tolerant groups. Starting from infancy, get them off of milk at a very young age and keep them off until their mid-twenties. I'd bet they'd be lactose intolerant.
I would bet the population groups that they say are lactose tolerant genetically are simply that way today because their families still use milk as generously throughout their life as their ancestors did. Their gut keeps a healthy supply of the right bugs to digest it, cause they keep milk in their diet. Raise their kids without milk and I'd bet they'd be as lactose intolerant as the Chinese seem to be.
There are those individuals everywhere in the world who are born without the right genes to digest milk ever, even mothers milk. They are the exception. I think the whole thing is what your body learns to respond to from a young age and continuing intp adult hood - for the most part.