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