Older siblings are likely to be more intelligent than their younger brothers and sisters — and to brag about it too, according to a new study.
Researchers found that first-borns tended to score higher on objective measures of intelligence, and to rate their intelligence more highly than younger siblings. The self-confidence could come down to comparisons in childhood and adolescence, when older children would have the edge because they were more developed, they said.
That left a “stable bias in self-estimations of intelligence, with later-born children slightly underestimating and first-born children slightly overestimating their actual cognitive abilities”, the researchers said.
The scientists, who looked at long-term population studies of 20,000 adults, found no link between birth order and personality traits. Even in intelligence, the differences were so small they would be unlikely to be detected in a family, researchers from universities in Mainz and Leipzig said.
Professor Stefan Schmukle, who led the study, which was published in Proceedings of the National Academy of Sciences, said: “The real news is that we found no substantial effects of birth order on any of the personality dimensions we examined.
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“This does not only contradict prominent psychological theories, but also goes against the intuition of many people.”