Sociology
The Demographic Causes and Consequences of Son Preference in East Asia
Quick fact
In the 1990s, South Korea's sex ratio at birth reached as high as 116 boys per 100 girls, far above the natural baseline of about 105, and although it has since normalized, China and other parts of East Asia still show significant imbalances.
Why this is interesting
In several East Asian countries, the natural balance of boys to girls at birth has been tipped—so much that there are tens of millions of 'missing women' in the population. Why would families deliberately prefer sons, and what happens to a society that has many more men than women?
Read the full explanation
Understanding The Demographic Causes and Consequences of Son Preference in East Asia
Imagine an ancient family tree where only sons can carry the surname, perform ancestral rituals, and care for aging parents. This deep-seated cultural preference for sons, known as son preference, is rooted in patrilineal traditions across East Asia. For centuries, this preference influenced family sizes but didn't distort the population's sex balance. Then, in the late 20th century, two things changed: governments introduced policies limiting family size (most famously, China's One-Child Policy), and modern medical technology like ultrasound made it possible to know a fetus's sex before birth. Suddenly, families who wanted only one or two children—and strongly preferred sons—could terminate pregnancies with the 'wrong' sex. With easy access to sex-selective abortion, the number of boys born per 100 girls began to rise. South Korea, Taiwan, and China all saw sex ratios at birth climb above natural levels. South Korea's ratio peaked in the early 1990s, while China's became even higher, reaching around 121 in some years. This wasn't just a passing trend; it's a shift in the demographic structure that carries decades of consequences.
A deeper explanation
The core mechanism behind son preference is a combination of cultural incentives and structural constraints. Confucian values, still influential in East Asia, emphasize patrilineal family continuity—sons inherit property, carry the family name, and are expected to support parents in old age. Daughters, in traditional view, marry into other families and thus are often seen as a 'loss.' Historically, this preference was muted because families had many children, hoping to get sons among them. But when fertility declines—due to urbanization, women's education, and family planning policies—families try to achieve their desired son within a smaller family size. This is where technology plays a role: prenatal sex determination (via ultrasound) and sex-selective abortion allow parents to avoid having daughters. The result is an elevated sex ratio at birth. The consequences ripple through society: a surplus of men of marriageable age (the marriage squeeze) becomes a major social issue. Men at the bottom of the socio-economic ladder may find it hard to find brides, leading to delayed marriage, social tensions, and even cross-border bride trafficking. Additionally, the imbalance contributes to an aging population, as the missing women reduce the pool of younger mothers, and may alter migration patterns. The phenomenon is not uniform: South Korea's SRB normalized after 2000, partly due to gender attitude shifts and policy efforts, but China's remains skewed, partly because of missing girls in previous cohorts creating a 'marriage market' imbalance that affects even the current generation. This illustrates how demographic structures, once set, can have self-perpetuating effects, and how cultural preferences intertwined with policy and technology can reshape an entire society's demography.