Based on their results, they concluded that first-borns are, in fact, smarter than later-borns.
However, the tests didn’t find evidence that birth position affected extroversion, emotional stability, agreeableness, conscientiousness, or imagination.
The researchers found a pattern that showed birth-order position increased intelligence by roughly 1.5 IQ points. It’s like the first-born child has 1.5 IQ points more than the second-born.
Of course, that wasn’t always the case. According to the results, the firstborn is 60% more likely to be intelligent than the second born.
Do you think this IQ difference is innate or developed?
You’ve probably heard that most of our intelligence is developed. Around 40% of our intelligence is genetically conditioned. The rest has to be built through the environment. The IQ differences between the kids are a result of the environment, not genes.
First-borns may have higher IQs because they get their parents’ undivided attention for a long time – something late-borns has to compete for right from the start.
The parents have higher expectations from their first child than the other kids, and as you know, higher expectations contribute to higher IQs in the long run.
Therefore, first-born kids are often left to take care of their younger siblings. It’s not uncommon for them to teach their younger siblings what they’ve learned.