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Science Says Sibling Rivalry Is Not Real

If you’re part of family where your siblings look nothing like you and you’re wondering whether or not one of you is predisposed to succeed in life while the other is predisposed to fail, experts at the University of Illinois and the University of Houston say that you don’t really have anything to worry about.

The study results showed that yes, order of birth does influence personality traits and intelligence, however the difference between fist borns and second borns, or later borns, are so small that they’re completely insignificant.

For their paper, published in the Journal of Research in Personality, the research team looked at the IQ levels and personality traits of no less than 377.000 high school students. Brent Roberts, project co-leader and psychology professor over at the University of Illinois, gave a statement stressing that the sample is a conspicuously large one. He quickly added that this is the biggest study in recorded history to ever look at birth order and its influence on personality traits and IQ levels.

Rodica Damian, project co-leader and psychology professor over at the University of Houston, gave a statement of her own informing why previous studies on the subject had a flawed approach. Previous studies were inaccurate because they typically worked with subject samples that were too small, and also used a research model than employed a “within family” comparison model.

But on top using a large sample of subjects, the new study also employed a new research model that compares children from different families with one another in order to obtain, better, more accurate results. Professor Damian explained that “[Within-family] studies often don’t measure the personality of each child individually”, instead “They just ask one child — usually the oldest, ‘Are you more conscientious than your siblings?’”.

She also informed that for a “within family” comparison model to be accurate, data would need to be collected from several generations. Each child born in the family would have to have their personality traits and IQ levels documented when they’re about the same age as the ones from previously documented generations, but this is not what researchers are currently doing.

The tests conducted by the team from University of Illinois and the University of Houston have shown the difference between the personality traits and IQ levels of older siblings and those of younger siblings is only a measly 0.02 points, nothing noticeable or significant in professor Roberts’ opinion.

The insignificant 0.02 correlation also applied to applied to the older siblings being more extroverted, conscientious, agreeable and having less anxiety.

Professor Roberts also added that unlike tests which reveal that a new drug can save 10 out of 10.000 patients, the same small effect is nowhere near as profound when it comes to personality traits. He stresses that two (2) people with a 0.02 correlation and sit them down, no one will be able to see the difference.

Professor Damian advices parents not to allow birth order to dictated their parenting approach because this order is not meaningfully related to their kid’s personality traits and IQ levels.

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