“We found no substantial effects of birth order on any of the personality dimensions we examined,” saidStefan Schmukle.
Lay people as well as a scientist share a number of beliefs: First borns are supposedly perfectionists, for example, while middle children develop a talent for diplomacy and last borns are expected to be rebellious.
The question of whether a person’s position among siblings has a lasting impact on personality has occupied scientists for more than 100 years, the study said.
To find out whether these differences actually exist, the researchers analysed the data of more than 20,000 grown-ups from Germany, Britain and the US.
They found that central personality traits such as extraversion, emotional stability, agreeableness and conscientiousness are not affected by birth-order position.
Small effects of birth positions were, however, found regarding self-reported intellect.
First borns were more likely to report a rich vocabulary and less difficulty understanding abstract ideas.
“This effect on intelligence replicates very well in large samples, but it is barely meaningful on the individual level, because it is extremely small,” Schnukle explained.
The study was published in the journal Proceedings of the National Academy of Sciences of the United States of America (PNAS).