Very few people know the real reasons for why the gender ratio is a problem in China. It is not due to the government forcing people to only have one child, because if that was the case, then it would be very imbalanced for the first child and balanced for more children. But it is in fact the opposite. Among first children the ratio is very balanced, but among second children and higher the number is out of whack.
The real cause of the gender ratio is abortions done in rural areas. They are often limited to two children and if they don't get a boy on the first try, then they certainly want the second child to be a boy. The consequence of the gender ratio will be lonenly farmers, not hordes of desperate men in the cities.