The Myth of the Only Child

Granville Stanley Hall, a big-name psychologist in the early 1900s, once said that “being an only child is a disease in itself.” Charming, right?

And he wasn’t alone. Alfred Adler also joined the party, painting only children as spoiled with neurotic parents. In fact, his go-to examples included one only child who killed his father after being cut off financially and another who was a “sexual pervert.” Very scientific. Very objective.

Fast forward to today, and not much has changed. The stereotype of the only child as a spoiled, lonely, socially awkward narcissist still shows up everywhere—from dinner conversations to media headlines. Cue the constant question to new parents: When’s the next one coming?

So, are the stereotypes true? Are only children actually worse off?

A meta-analysis (a study that summarizes lots of studies) from 1986 looked at intelligence, sociability, achievement, self-esteem, behavior, leadership, cooperation—you name it. The verdict? If anything, only children looked better off. And when compared specifically to kids from two-child families? No differences.

More recent studies tell the same story. One examined whether people think only children are more narcissistic (they do). It also asked only children what they think (they kinda agree). But when researchers tested actual narcissism levels? Surprise: only children scored a bit lower on narcissistic admiration.

Same goes for prosocial behavior—people assumed only children would be less generous or helpful. But actual data? No differences. And again this is also true for well-being.

One massive study with over 20,000 adults looked at personality traits—things like extraversion, conscientiousness, neuroticism, honesty, openness. They found small, statistically significant differences between only children and those with siblings. only children reported slightly lower levels of conscientiousness and honesty-humility, and slightly higher levels of neuroticism and openness. But these differences were tiny—like, “a 3.58 vs. 3.46 on a 1-to-7 scale” tiny. And the study didn’t even adjust for important confounders (variables that may provide alternative explanations to findings) like socioeconomic status or parental personality. So even those minuscule differences probably don’t mean much at all.

This is exactly why statistical significance without looking at effect sizes can be so misleading.

Here’s another example of that confusion: One study found that the more siblings you have, the lower your risk of divorce as an adult—by 3% per sibling. Sounds compelling! Until the researchers accounted for confounding factors (those that may provide alternative explanations to findings that are based on correlations) like socioeconomic status… and poof, the effect disappeared.

A child’s development is shaped by their parents’ characteristics, the environment they grow up in, and, yes, biology and genetics. If parents of only children in a given culture or era tend to be older or more educated, then certain traits may show up more often in only children—but that likely reflects the shared circumstances of their families, not the fact that they have no siblings

Lastly, and as an anecdotal aside, as it is not based on a meta-analysis or data from various cultures and populations: A few studies show that having more children beyond the first can decrease a mother’s life satisfaction. Yes, the mother’s well-being and mental health deserve some attention too.

The Bottom Line

Only children aren’t more spoiled, selfish, or maladjusted than the rest of us. The early psychologists were wrong. The stereotypes don’t hold up. And maybe it’s time we stopped judging parents for having “just one.”

References

Falbo, T., Only children: An updated review. Journal of Individual Psychology, 2012. 68(1).

Rezende, N. 2021; Available from: https://www.onlychildworld.com/blog-posts/how-many-families-worldwide-have-only-one-child.

Falbo, T. and D.F. Polit, Quantitative review of the only child literature: research evidence and theory development. Psychological Bulletin, 1986. 100(2): p. 176.

Dufner, M., et al., The end of a stereotype: Only children are not more narcissistic than people with siblings. Social Psychological and Personality Science, 2020. 11(3): p. 416-424.

Zheng, X., et al., They Are Not Little Emperors: Only Children Are Just as Altruistic as Non-Only Children. Social Psychological and Personality Science, 2022. 13(2): p. 543-552.

Tang, J., et al. (2025). "How growing up without siblings affects the adult brain and behaviour in the CHIMGEN cohort." Nature human behaviour: 1-18.

Stronge, S., et al., Only children in the 21st century: Personality differences between adults with and without siblings are very, very small. Journal of research in personality, 2019. 83: p. 103868.

Merry, J.J., D. Bobbitt-Zeher, and D.B. Downey, Number of siblings in childhood, social outcomes in adulthood. Journal of Family Issues, 2020. 41(2): p. 212-234.

Goisis, A., et al., Only children and cognitive ability in childhood: a cross‐cohort analysis over 50 years in the United Kingdom. Population and development review, 2023. 49(2): p. 319-349.