Shifting Sex Ratios

By josh donlan on April 5, 2008.

In some Asian countries (e.g., India, China, South Korea), it is well documented that male births often far exceed female births. In India the ratio is 1.39:1 and in China it is 2.25:1. Many point to China's one-child policy, high-dowry payments in India, or reliance on children for support as important drivers of the observed sex ratios (the biological norm is 1.05:1). New research to be published in the Proceedings of the US National Academy of Sciences challenges those factors. U.S.-born children of Chinese, Korean, and Asian parents also show a male-biased sex ratio. In 2000, if a couple had no previous sons, their third child was 50% more likely to be a son (1.51:1). The researchers point to the availability of prenatal sex determination and abortion as key factors contributing to the observed sex selection. The use of such medical technology explicitly for sex selection raises as suite of interesting ethical questions that many would rather turn their head than debate.

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Thanks for blogging this, but I don't see how this research really challenges our understanding of what's happening in the nations you highlight. It seems to me that male children are deemed to be more valuable for whatever reason and people do what they feel they have to to obtain them regardless of which nation they inhabit.

Um, I haven't looked at the PNAS article in question, but I'd say that the US data you mention strengthens rather than challenges the hypothesis that higher male:female birth ratios are due to selective abortions. Some of the countries you mention have PR campaigns and (marginally enforced) laws against pre-natal sex determination. Presumably as people with these sociological impulses move to the US where such measures are absent, they are free to give full rein to their desires for a male child. They are also more likely to do this after being initially "disappointed" with one or more daughters.

Perhaps a comparison of sex ratios of aborted fetuses amongst various populations/cohorts would clarify this issue.

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