Birth Order Has No Effect on IQ, Personality: Major Study

Think you’re smarter or more responsible than your siblings because you’re the first born? Think again.

New research, tracking the intelligence levels and personality traits of more than 377,000 high school students has found birth order has virtually no influence on IQ or other personal characteristics, Medical Xpress reports.

Although the study, in the Journal of Research in Personality, did find slight slightly higher IQs among “first borns” — equating to about 1 point — the researchers said the differences were so small that they have no practical relevance to people's lives.

"This is a conspicuously large sample size," said University of Illinois psychology professor Brent Roberts, who led the analysis with postdoctoral researcher Rodica Damian, a professor of psychology at the University of Houston. "It's the biggest in history looking at birth order and personality."

Roberts added that the analysis also revealed first borns tend to be more extroverted, agreeable, conscientious, and less anxious than later borns, but those differences were "infinitesimally small," amounting to a correlation of 0.02 percent.

"In some cases, if a drug saves 10 out of 10,000 lives, for example, small effects can be profound," he said. "But in terms of personality traits and how you rate them, a 0.02 correlation doesn't get you anything of note. You are not going to be able to see it with the naked eye. You're not going to be able to sit two people down next to each other and see the differences between them. It's not noticeable by anybody."

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