The significant achievement in the long-term effects of sibship size on adults' mental health and subjective well-being was reported entitled ''Do fewer siblings lead to better mental health and subjective well-being? Evidence from China's family planning policies'', which was made by Associate Professor Zhuang Hao from the School of Economics and Management, Beihang University together with Huihui Cheng from Rutgers University. The study provides evidence of the long-term and non-monotonic causal effects of sibship size on adults' mental health and subjective well-being by exploiting two of China's family planning policies as natural experiments. The findings indicate that having more siblings leads to adverse effects on adults' mental health and subjective well-being and interestingly, being the only child also worsens mental health in adults. The study also finds supportive evidence that adults without siblings have better physical health but are less agreeable and more neurotic than those with siblings. These seemingly contradictory findings reconcile the theory of quantity-quality tradeoff and the studies on the only-child disadvantage and advance understanding of the impacts of sibship size on mental health and subjective well-being. It provides valuable reference for policymakers when designing family planning or social welfare policies.
