How did I become so tan? I'm asian?

As a child I lived in the east coast but was always very pale. My sister was always quite tan. However, now I am fairly tan, the only parts of me still pale is where my pants and shirt cover up and my underarms. I might have grown out of my original skin color, I know people tend to be naturally paler as children. But I'm thinking it's because the change of climate. I probably have a naturally pale skin color, but an easy ability to tan. Or maybe because I got tanned as a child, it got stuck that way? I don't know I'm curious though. By the way, I'm korean .