The Happiness Paradox of Birth Order

That happiness tracks income is an abiding finding in the social science literature. First-born children tend to have higher socioeconomic attainment than later-borns, and therefore are expected to be relatively happier. Using data from representative U.S. surveys (approximately 15,000 individuals and 7,000 siblings), I find that although first-borns have substantially higher income levels, birth order effects on indicators of psychological well-being—life satisfaction, positive affect, and mental health—are statistically non-significant. Nevertheless, observed first-born effects on life satisfaction, albeit small, align with differences implied by birth order income gaps and the income–well-being gradient. By contrast, first-borns have significantly lower levels of positive affect and mental health than implied by their income advantage, revealing a happiness paradox. Possible explanations for the paradox are explored. These findings highlight the relevance of social context in shaping the income–happiness link, and invite investigation into relational determinants of well-being that may be independent of material success.

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