20 years ago you NEVER saw Asian women with large natural breasts, now there are more than ever.
Natural selection?... fast foods?... estrogen in the water?
i remember a report stating that Japanese women are getting larger breast sizes due to higher protein diets (Western). But the breast cancer rates have increased. So, you have Westernized diets---fast food, etc that is possibly screwing with estrogen levels. The thing is, they still are a more rarer sight than there white and black counterparts, hence the fetishism.