Recent research has told us that our birth order can affect our health — that firstborn children are more likely to have a higher weight and BMI as they grow older (boo). However, what we’ve always taken as universal truths about birth order and personality (the oldest are overachieving and bossy and youngest are rebellious, for example) may actually just be one big giant myth, according to a recent study.
The study, which was conducted by German researchers and published in the Proceedings of the National Academy of Sciences, pooled over 20,000 subjects — half who were German, a quarter American, and a quarter British. They not only wanted to compare people within their individual families, but compare different sibling sets; they did so via surveys about their birth order, their IQ, their view of their own intelligence, and the Big Five Personality Test (which measures extroversion, neuroticism, agreeableness, conscientiousness, and openness).
One of the birth order stereotypes that did hold up: The oldest siblings tended to score highest on the IQ test, with IQ scores declining slightly with every subsequent sibling. (This could be because first-time parents tend to be sticklers with education because they’re paying more attention to making sure their child learns what they need to learn early on.)
However, there were no other strong correlations between personality and birth order, no matter how the researchers tested it. They tried testing large age gaps (which previous studies had suggested accentuated personality differences), but found nothing. “It was surprising the results are so clear,” Julia Rohrer, a graduate student in psychology at Germany’s University of Leipzig and one of the authors of the paper, told TIME.
Rohrer also noted that when it comes to the IQ result for first-born children, it’s possible that it’s a self-fulfilling prophecy — the oldest children are aware of the stereotype, so they try harder, and their siblings follow with what they believe is their own stereotype.
Naturally, this is just one study; though it has a large sample size, it doesn’t debunk previous studies on birth order. But it certainly does suggest that a lot more research has to be done on the subject — and that we should probably second-guess those birth order stereotypes. We’re more than our birth order, folks!
(Image via Warner Bros Television.)