Would Tibetans growing up in the West become less tanned than Tibetans in Tibet?

One of the easiest way to tell Tibetans from Chinese is basically through skin color. Even when Chinese migrants get sunburned, they rarely become as tanned as Tibetans.

But are Tibetans who grow up in the West less tanned, or Tibetans generally have naturally darker skin color than other East Asians?