Yes, we do have an idea.
Abusing booze and smoking will take their toll on any skin type. The main difference between Caucasian and Asian skin is the amount of melanin produced which protects the skin from UV damage, one of the main factors in skin aging. Whites produce less melanin so are more susceptible to photo damage. This is probably the main reason many whites don't age as well as other races. Having said that, there are many ways to combat photo damage starting with a simple application of a cross spectrum sunscreen, healthy diet, and of course, as you mentioned, avoiding booze/smoking which really accelerates the aging process.
If whites followed such a lifestyle plan, they'd look as young as their brethren.