Aren't Asian males the largest ethnic group? More males are born than females. While males tend to die more often of illness, accident, and violence, females die more often in childbirth. (Until recently, men outnumbered women even in the U.S. due to deaths in childbirth. Even all the male deaths in the Civil War created barely a blip in the demographics compared to deaths in childbirth.) Add to this the preference for male children in many Asian cultures, and the sex ratio is quite skewed. They are worried that many men won't be able to find wives at all in China, because of their one-child policy. If families can only have one child, they want it to be a boy.