Why do all Chinese people have black hair?
Gwydion Madawc Williams, Read a lot about this
Answered Sep 6, 2015
Black hair is the global norm. Other shades are mostly seen when levels of sunlight are low. Not true of most of China, so few have anything other than black hair.
Answered Sep 19, 2015
Hair color was originally black, but because of the different environments where our ancestors evolved, some mutations occurred. Another thing is that it is hard for lighter hair color to be commonly observed in large population of black hair, because black hair color is the dominant gene.
Despite this, Chinese hair isn't all black, if you observe many people you can see that there are actually different shades of black, and there are some people (very few) who has hair color such as reddish or brownish.