VoxEU Column Development

Too many boys…

China’s one-child policy led to an explosion of the boy-girl ratio in the ‘80s and ‘90s. As this “only child” generation reaches adulthood, problems – including rising crime rates – are starting to appear.

China is gradually getting rid of the vestiges of its communist past. But the demographic policy of the 1980s and 1990s planted a time bomb, and its effects are just starting to be felt.

Its best-known aspect is the one-child policy, first put in place in 1978 and still in practice, though in a more relaxed form. Today, a couple made up of two only-children are allowed to have two children. In rural regions, a couple whose first child is a girl is normally authorised to have a second. But in the ‘80s and ‘90s, the one-child policy was strictly applied, albeit not uniformly across regions. Parents were penalised for births “outside quota”. They were fined and were financially responsible for the education and health-care of “extra” children.

Envisioned by Deng Xiaoping, this aggressive fertility control strategy marked a rupture with the Mao period, which had launched the slogan “more people, more power”. Xiaoping considered fertility control essential to getting a handle on the economy, the foundation of China’s success.

The one-child policy was a great success in terms of controlling fertility. But in a country where there was already a strong cultural preference for boys, it resulted in a serious imbalance between the number of girls and boys; the widespread use of techniques for determining a foetus’s sex opened the door to sex-selective abortion.

The preference for boys, sex-selective abortion, and excessive mortality of young girls isn’t an exclusively Chinese phenomenon and isn’t therefore entirely due to the one-child policy. This phenomenon is seen in India, Taiwan, Pakistan, and even in the United States in communities made up of immigrants from these countries1. But the one-child policy accentuated this imbalance, by “forcing” parents who wanted at least one boy to eliminate girls from the first children born to them. For example, in Taiwan, where fertility wasn’t controlled, the liberalisation of abortion in 1986 led to significant sex-selection of children, but only starting with a couple’s third child2. In the People's Republic, governors in each province had some latitude in implementing the policy, and in certain regions, since the ‘80s, parents have been allowed to have a second child if their first-born was a girl. In these areas, the boy-girl ratio is more or less normal for first-births and catastrophic for second births.3

All of these factors combined, including the one-child policy, led to an explosion of the boy-girl ratio in the ‘80s and ‘90s: there were about 102 boys for 100 girls among children born in 1978, and more than 112 boys for 100 girls among those born in 1998. Today, there are 37 million more men then women, and there are as much as 120 boys born for 100 girls.

This “only child” generation is now reaching adulthood. A child born in 1980 is now 28 years old, and China is beginning to realise the consequences of this demographic imbalance. Among 16-25 year olds today, there are nearly 110 boys for every 100 girls. Boys are having trouble getting married. And young men, particularly single ones, have more behavioural problems and commit more crimes than young women. It has been argued that the “frontier town” mentality of the United States is responsible for its high propensity to violence. Since 1998, the number of crimes has risen 13% per year on average. Seventy percent of criminals arrested are between 16 and 25 years old, and 90% are male.

To what extent is the rise in the number of young men responsible for the increase in crime? A recent study by Chinese and American researchers: “Sex ratio and crime: Evidence from China’s one-Child Policy” (by Edlund, Li, Yi, and Zhang) answers this question by comparing the increase in the number of crimes between 1998 and 2004 in regions where the one-child policy was strictly enforced with the same increase in regions where parents were allowed a second child if the first were a girl (where the boy-girl ratio is much closer to normal). They conclude that the one-child policy explains one-seventh of the increase in crime.

Besides the mechanical effect of the increase in the proportion of boys (and therefore potential criminals) in the population, the difficulty that young men have getting married is probably one source of this phenomenon.

A long-term study of Vietnam veterans in 1998, cited in a recent New Republic article, provides some clue as to why. The subjects' testosterone levels, which are linked to aggression and violence, dropped when they married and increased when they divorced. Men who remain single maintain high levels of testosterone, which may make them particularly aggressive.4 

Another factor is that of being raised as an only child. One study shows that girls born in regions where a second child was permitted have stayed in school longer than those in regions where they were the only child. It seems that far from creating competition, siblings benefit each other.5 The only-child generation is perhaps a generation of lonely children.

Whatever the case may be, and even though the one-child policy is on the decline, it will continue to haunt China for decades to come.


1 See Jason Abrevaya “Are There Missing Girls in the United States? Evidence from Birth Data”, forthcoming in the American Economic Journal: Applied Economics and Almond, Doug and Lena Edlund “Son-biased sex ratios in the 2000 United States Census.” Proceedings of the National Academy of Sciences, 105: 5681-5682

2 See Lin, Ming-Jen, Liu, Jin-Tan and Qian, Nancy (2008) ”More women missing, fewer girls dying: The impact of abortion on sex ratios at birth and excess female mortality in Taiwan” CEPR Discussion Paper 6667

3 See Qian, Nancy “Quantity-Quality: The Positive Effect of Family Size on School Enrollment in China” Brown University mimeograph

4 “No Country for Young Men”, by Mara Hvistendahl, New Republic, July 9, 2008

5 Qian, Nancy “Quantity-Quality: The Positive Effect of Family Size on School Enrollment in China” Brown University mimeograph

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