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Is China’s one-child policy really to blame for personality changes?

People born in China under the one-child policy (OCP) – a policy applied since 1979, restricting urban couples to having only one child – are less trusting, trustworthy, competitive, conscientious, risk-seeking…

China’s “little emperors” may have been unfairly characterised. Saf'

People born in China under the one-child policy (OCP) – a policy applied since 1979, restricting urban couples to having only one child – are less trusting, trustworthy, competitive, conscientious, risk-seeking, and optimistic than those born prior to its implementation.

At least, that was the finding of a recently-published article by Australian economists in Science Express.

With this in mind, imagine you are one of the many individuals born under the OCP. According to the research, you are one of the xiao huangdi, a “little emperor”, privileged and pampered by indulgent parents. You have several undesirable psychological characteristics, and the OCP is to blame.

Now, imagine a different scenario. You are a Chinese policy-maker being lobbied to abolish the OCP. You’ve endured years of bleating about the appalling consequences of the policy, such as the gender imbalance resulting from abortions of baby girls and the increasing proportion of elderly people with fewer offspring to care for them.

You’re now told that those born just after the introduction of OCP – who are now in their thirties – perform more poorly on a range of psychological measures than those born pre-OCP, just a few years older than them.

Both individuals would be justified in asking for evidence: these are, after all, strong claims with significant implications.

But is the evidence compelling or merely suggestive? Suggestive data are fine if conclusions drawn from them are suitably restrained. In the Scottish philosopher David Hume’s words: “a wise man […] proportions his belief to the evidence.”


Using a range of economic games involving decisions about giving and investing money, and sophisticated regression analysis, the authors of the Science Express paper – from Monash University, ANU and the University of Melbourne – drew the conclusions referred to above: those born prior to the OCP (1975 or 1978 for the purposes of the study) are more trusting, trustworthy, competitive, conscientious, risk-seeking, and optimistic than those born under the OCP (1980 or 1983).

The individual born under the OCP may want to ask: is there really a difference between those born under OCP versus pre-OCP? The policy-maker will want to know whether the OCP really caused this difference.

Taking the Science Express article at face value, the answers appear to be “yes” and “yes”. Group differences (for example, OCP participants invested 58% of a hypothetical sum versus 66% in the non-OCP group) are adorned with asterisks – the more, it seems, the better.

The term “causal” is used five times and “impact” ten - these are bold terms, describing a relation that is much more precise than mere association. The results, at first glance, could hardly be clearer.

Same but different

But are there really differences between the people studied? In simplified terms, a result in social science is typically called “significant” if the probability of the result occurring merely by chance, rather than reflecting a real difference, is low. The widely-accepted criterion is 5%.

In the Science Express paper, when controlling for relevant variables to rule out alternative explanations, four of the five differences in behavioural outcomes (trust, trustworthiness, risk-taking, competitiveness, but not altruism) are labelled “significant”, but using a criterion of 10%.

Had the widely-accepted 5% cut-off been used, two of the outcomes (trustworthiness and competitiveness) would not have been labelled significant.

Although the cut-off is largely arbitrary and somewhat flexible, the fact remains that for two of the outcomes, a conclusion of “no difference” is admissible by widely-accepted standards.

And invoking effect sizes – an alternative way to compare groups – does little counter this: the effect sizes for trustworthiness and competitiveness are smaller than for trust and risk-taking. In short, some results are marginal at best.


Alternative realities

So can the supposed differences in trust, trustworthiness, competitiveness, conscientiousness, risk-seeking, and optimism be attributed to the OCP?

The authors controlled for a range of variables in order to rule out alternatives. They also correctly describe the study as a natural experiment, which is to say their groups are naturally occurring rather than randomly allocated.

The problem with natural experiments is that alternative explanations cannot be easily dismissed.

Tobacco companies understand this all too well: “the deceased did smoke our cigarettes and die from lung cancer, Your Honour, but was also exposed to asbestos …”

Perhaps the OCP is the most likely explanation for the group differences, but are there alternatives?

The bigger picture

China experienced dramatic societal change over the period in question. The Cultural Revolution ended around 1976 and triggered the opening of China’s economy. China established diplomatic ties with the United States in the very year the OCP was introduced. In other words, a lot was going on.


The extent to which the authors statistically control variables purported to assess these alternatives (e.g. attitudes to government intervention as an indicator of the effect of the opening of the economy) is admirable, but involves many assumptions.

The OCP may be the most likely explanation of the group differences, but alternative explanations are not completely precluded by the data.

So, are there really differences in these psychological variables between those born pre- and post-OCP? Yes, but some are marginal. Can these differences be attributed to OCP? Perhaps – although several plausible alternative explanations cannot be dismissed.

The push for the abolition of OCP can gain momentum if strong evidence for its negative implications is discovered. Strong claims based on merely suggestive evidence from a single study on a narrow sample will convince nobody with influence, and perhaps only offend a population of young Chinese-born individuals who must wear the “little emperor” label.

The conclusions, to reiterate Hume, are not yet proportional to the evidence.

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10 Comments sorted by

  1. Alexsandra Louise

    Enrolments and Marketing Manager at Perth Montessori School

    The research can just as easily be attributable to "birth order" / "only child" but in an environment where everyone is an only child that is factor that is of interest. How would the typical characteristics of an only child play out in an environment of "only children".

  2. Stephen S Holden

    Associate Professor, Marketing at Bond University

    Sorry to split hairs, but if we're going to dissuade people from any misunderstanding about correlation and causation, let it extend to statistical testing too!

    You said: "a result in social science is typically called “significant” if the probability of the result occurring merely by chance, rather than reflecting a real difference, is low"

    It is not "the probability of the result occurring merely by chance", but the probability of the observed result under an assumption of no relationship between the variables (see for a 'lite' effort to explain this to the wider public.

    And then, it is certainly generally presumed that statistical significance reflects a 'real difference', but that really is another bigger issue: see

    1. Dan Costa

      Lecturer and Researcher in Psychology at University of Sydney

      In reply to Stephen S Holden

      Stephen, that's not splitting hairs at all, but my statement was an attempt to simplify what is a complex idea within the constraints of everyday language. Your statement is both more precise and accurate, but after years of teaching statistics I'm not convinced a reader not already well-versed in null hypothesis significance testing would understand it (I am, however, willing to be proven wrong). Giving some leeway for the translation from technical to lay language, my description may not be optimally phrased but I don't think it is incorrect.

      Thanks for the useful links. That broader issue needs far more publicity.

  3. Colin MacGillivray

    Architect, retired, Sarawak

    Excellent article. There are clearly too many variables at work and the effect is minimal.

    Note to TC editors: Please could a political expert write about why the Chinese method of selecting a leader for a fixed period is better than democracy?

    1. Yanshuang Zhang

      PhD Candidate at University of Queensland

      In reply to Colin MacGillivray

      Haha that would be inviting criticism even attacks. Somebody tried before but as far as I know out of the protection of him many comments had to be deleted.
      But your suggestion still holds because every system has a flip-side and especially in this post-capitalism/ post-socialism era, confronting some same development conundrums, serious reflection and introspection should become our common quest.

    2. Colin MacGillivray

      Architect, retired, Sarawak

      In reply to Yanshuang Zhang

      Hi Yanshuang, my post was meant to provoke! Just this week the Roman Catholic Church selected its boss in a similar way to China- an "electoral college" of informed senior people.
      Whereas here in Australia, a small party faction can eject a Prime Minister at any time, ignoring possible input from party members or the public.

  4. Tony Xiao

    retired teacher

    The Chinese Academy of Social Sciences concluded recently and correctly that the sample size of 421 well-educated Beijing residents is not big enough to account for the whole of Beijing, let alone China and is nothing more that stereotype research and based on personal observations, I wholeheartedly agree.

  5. Antony Eagle

    Senior Lecturer in Philosophy at University of Adelaide

    I think the substantial objection raised to the research under discussion is very reasonable. But the framing using both Hume's dictum and observations on statistical significance raised some issues for me.

    If hypothesis testing is to guide belief at all, it must do so by giving binary recommendations to 'accept' or 'reject' the null hypothesis, at a certain pre-determined level of significance. But if we're really going to *proportion* our belief to the evidence, then we'll need belief states that are more fine-grained than simple 'on-off' belief. So it's tricky to see how we could follow Hume's otherwise platitudinous advice with only the resources of hypothesis testing available to us. (By contrast, it's easier to see how to proportion one's belief to the evidence if one has something like Bayesian *degrees of belief*.)

  6. Yanshuang Zhang

    PhD Candidate at University of Queensland

    I think the "bigger picture" in this case should be the main acting factor. Just wonder how he quantifies and evaluates the socio-political influence on individual.

  7. Kim Darcy


    Dan, sorry, just to clarify, but are you saying" less trustworthy, less competitive, less conscientious, less risk-seeking, and less optimistic?" That makes the current China population lazier and more depressed than their forbears, something I would find very difficult to accept, as I watch the Chinese both in China, Australia, and across the world. I'd say zippy, passionate traders, academically excited, and definitely ascendant.