As mentioned in the other thread, I’m half German half Taiwanese, born and raised in Germany and do hold both passports. Even though it is mathematically not correct, I consider myself 100% German but also 100% Taiwanese, which makes me in my own sense a westerner as well as an Asian at the same time. I feel this way, because I have both cultures in me and consider both countries my home. Giving up one or the other would break my heart.
Nevertheless growing up as a mixed-race kid was sometimes not easy, because neither side really sees you as a native, which makes you basically a foreigner everywhere and you have a sense of not belonging. But when you get older things change and I started to realize that it is rather gift than a curse. 
So for me, being a westerner isn’t limited to the appearance, growing up in a western country can also make you a westerner. But I see that many people, also taiwanese, think that westerners ought to have a certain physical appearance.