“In the future, there will be millions of men who can’t marry, and that could pose a very big risk to society,” warns Li Shuzhuo, a leading demographer at Xi’an Jiaotong University.

China’s official one-child policy was a huge factor in the today and future imbalance

Out of China’s population of 1.4 billion, there are nearly 34 million more males than females — the equivalent of almost the entire population of California, or Poland, who will never find wives and only rarely have sex. China’s official one-child policy, in effect from 1979 to 2015, was a huge factor in creating this imbalance, as millions of couples were determined that their child should be a son.

India, a country that has a deeply held preference for sons and male heirs, has an excess of 37 million males, according to its most recent census. The number of newborn female babies compared with males has continued to plummet, even as the country grows more developed and prosperous. The imbalance creates a surplus of bachelors and exacerbates human trafficking, both for brides and, possibly, prostitution. Officials attribute this to the advent of sex-selective technology in the last 30 years, which is now banned but still in widespread practice.

In the two countries, 50 million excess males are under age 20. Washington Post, April 18, 2018