1. Too many boys…
Esther Duflo
18 August 2008
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
liberalization 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 than 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 realize 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 behavioral
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

2. 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.
Footnotes
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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