I have been living in Malaysia for about 4 years now and I walk every day in my neighborhood. Rain or shine. I can feel the hot sun beating down upon me and I also most always sweat profusely. When I returned to the US in August some of my friends mentioned that I was as white as when I left. I had no color. I had noticed this phenomenon before and have discussed it with some of my Western Caucasian friends, who also had no color. They couldn't explain it either. I have seen some Caucasian women with a very dark tan, who probably spent a lot of time lying in the sun. I haven't seen too many men with a tan though.
When I lived in the US, the months of July and August were much the same as the heat and humidity here in Malaysia. I didn't spend as much time walking in the sun in the US, but at the end of the summer I had a tan. When I returned to Malaysia from my 3 week vacation in the US I had a tan, which was quite noticeable by friends and acquaintances. Amazingly when I returned to my regular routine of walking in the sun every day, my tan faded. I don't get it. It's not as though I want to sunbathe all of the time to get a tan, that most people here were born with, but I don't understand why I don't get any color at all. Very strange.