I'm very skeptical of this. I was born and raised in Asia, and all of my peers were raised on a diet with regular milk consumption. So either we were a huge cohort of statistical outliers or that number is way, way off.
I do know that lactose intolerance rates for Asians is much higher (and consequently, less socially troublesome due to the fact that dairy is generally not a core part of cuisine), but 90% is way, way, way out there.
[1] http://en.wikipedia.org/wiki/Samudra_manthan
[2] http://en.wikipedia.org/wiki/File:Krishna_with_flute.jpg
Interestingly, my wife and I grew up on milk in India (to adulthood), but found ourselves mildly lactose-intolerant to American milk.
Edit: changed "includes" to "excludes".
the difference is I can drink a quart of milk (a little under a liter) without any side effects
All of the Indians I know are fine with milk and my understanding is that milk is now part of the regular childhood diet in Japanese school lunches [1].
Anecdotally, I do know a few Chinese Americans who grew up in the U.S., moved to Hong Kong during their middle and highschool years, didn't tough the stuff while there and came back lactose intolerant as adults. So I suppose it may be an acquired skill one has to keep up with? (their younger siblings who didn't make that trans-pacific journey are fine with milk)
Anecdotally, this seems untrue. I was back in China for 2 months earlier this year and milk (fresh, no less, with expiration days of literally 3 days or less) are sold everywhere. Clearly there is a high demand for milk in mainland China (so much so that there are even brands of imported milk from Germany). This was in the capital of Beijing.
Actually, a little more looking, I think I also found the Yale study it's from. Here's the power point: http://cst.yale.edu/sites/default/files/worldwide distribution of lactose intolerance, madison 2010.pptx
Or perhaps East Asians developed different kinds of social and economic structures that mitigated the disadvantage of not being able to consume milk.
Or perhaps the necessary mutations just didn't get incorporated into East Asian genes. Also according to the article, the lactose tolerance gene spread as far as India but didn't cross the Himalayas.
[1]: http://sourcing.indiamart.com/agriculture/articles/origin-an...
Milk allergy: http://en.wikipedia.org/wiki/Milk_allergy
Understanding and Managing Your Child's Food Allergies: http://www.amazon.com/Understanding-Managing-Allergies-Hopki...
-- asian who drinks milk daily.