Does birth order impact overall intelligence? It’s a question researchers have been asking for centuries and continue to investigate today. And while there are many factors that contribute to personality and smarts, studies do show that where you fall in your family tree may have some impact on the person you become and the I.Q. you achieve. (See also: Good and Bad Habits of Smart People)
Here’s what we know.
First Born Smarts
As the eldest in my family of two kids, I’m happy to report that a Norwegian study published in 2007 supports my brain power over my brother’s. Researchers examined military IQ tests of 18- and 19-year-old men and corrected for factors that might otherwise skew data, including maternal age, parents’ education level, and total family size. In the end, first born children scored an average of 3% higher on intelligence tests than second children (103.2 versus 100.3) and 4% higher than third borns (who scored 99.0 on average).
What’s interesting to note is that younger siblings — second borns, in particular — seem to score higher on their I.Q. tests before age 12. The theory behind these findings? When kids are younger, the first born is impacted by his or her siblings, even negatively when it comes to both language and cognition. On the flip side, big brothers or sisters have the opposite effect, enriching the lives and brains of their kid siblings. This situation changes over time, perhaps as the eldest matures and fosters the intelligence (tutoring, etc.) of the rest of the pack.
Rank and Circumstance
There are other notable factors that have the power to shift these basic findings. For example, if the eldest sibling in a family dies and the second-born is, then, bumped up in the lineup, the game changes. This kind of circumstance results in beefed up scores for a second born, who then becomes, for all intents and purposes, the biological and social leader to the rest of the kids in the family.
Age Gaps, Family Size, Etc.
Still, it’s hard to declare first borns are inherently smarter than their siblings because so many other variables are at play. If there’s not much spacing between brothers and sisters, for instance, birth order appears not to matter quite as much. In fact, small age gaps have shown an “unfavorable” impact on I.Q. levels. And there does seem to be some relationship between overall family size and smarts as a whole for everyone involved, but — again — the dynamic is complicated and requires further study.
Then there are those only children — how do they stack up? Well, hundreds of studies in the 1980s — that continue to gain support today — show that only children often score significantly higher on intelligence tests, all while boasting higher self-esteem and emotional lives. The idea is that parents with only one child (a one in five chance in America) are able to devote all their resources, both time and money, giving singletons the best of all worlds. However, these benefits come with a price. Stress increases with age for only children, as they are taxed with facing elder care and other issues without the help of siblings.
So? Does all this match your own experience? Please share in comments!