Only Children: Are They Really All That Different?

New research compares the personalities of adults with and without siblings.

Posted Nov 15, 2019

Source: Peakpx

Deserving or not, only children are often faced with what some might consider "personality discrimination." They are perceived to be spoiled and unlikeable. According to a recent Gallup survey, only 3% of American adults would describe a one-child family as ideal. 

But is there any truth to these notions? Or, are they just another example of misguided prejudice?

New research forthcoming in the Journal of Research in Personality might have an answer. A team of psychologists led by Samantha Stronge of the University of Auckland in New Zealand examined the personalities of adults with and without siblings to see if they could uncover any meaningful differences.

They found scant evidence to suggest that adults without siblings were any different from adults with siblings.

"One-child families are increasingly prevalent, yet negative beliefs about only children persist," state Stronge and her team. "These negative views are commonly held and may impact, among other things, family planning decisions and patient perceptions among health professionals. The current research robustly tested differences in Big-Six personality between adults with and without siblings in a large national panel sample, and found differences that, while statistically significant, did not rise to the level of a practical effect."

To arrive at this conclusion, the researchers examined data from 21,937 New Zealanders who participated in the New Zealand Attitudes and Values Study (NZAVS). In this study, participants were asked to complete a condensed version of the HEXACO personality inventory. For those unfamiliar with this test, HEXACO measures six core dimensions of personality: honesty-humility, openness to experiences, neuroticism, conscientiousness, agreeableness, and extraversion. Participants also reported whether or not they grew up with siblings and answered a series of demographic questions.

Interestingly, the researchers found that adults without siblings scored lower on the honesty-humility and conscientiousness dimensions of personality. They also found that these individuals reported higher levels of neuroticism. In other words, there is some truth to the idea that only children are more likely to possess some of the more unfavorable personality traits.   

However, the researchers also point out that the differences between the groups were far too small to have real-world implications. For instance, the odds that a randomly selected adult without siblings would be any less honest than an adult with siblings is approximately 52.5%, according to the researchers. Compare that to the odds of a randomly chosen male being taller than a randomly chosen female (92%), and you can see why this finding does not hold much water in the real-world.

The authors conclude, "Though negative perceptions of only children endure, the perception does not stack up against the empirical evidence. We infer that any personality differences between adults with and without siblings are vanishingly small."

These findings align well with another recent study, published in the journal Social Psychology and Personality Science, which found no difference between adults with and without siblings in the likelihood of exhibiting narcissistic personality traits. 

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Stronge, S., Shaver, J. H., Bulbulia, J., & Sibley, C. G. (2019). Only children in the 21st century: Personality differences between adults with and without siblings are very, very small. Journal of Research in Personality, 83, 103868.