It’s common for firstborn kids to believe they’re smarter than their younger siblings—they do get a little head start after all. They’re usually the first to learn new things and reach important life milestones. Now, fresh research reveals this isn’t just about age. Firstborns really do tend to be smarter and more successful than their younger siblings.
What Could Be Behind This Difference?
Researchers from the University of Edinburgh and the University of Sydney found that firstborn kids generally have higher IQs, perform better in school, and earn more later in life. The main reason? Parents usually encourage firstborns more to think creatively. Younger siblings don’t get quite the same push—not because firstborns get more emotional support, but because of how parents engage with each child.
Think about it: with the first child, parents often have more time for mentally stimulating activities like reading, storytelling, and playing instruments.
Experts also found that moms are more likely to smoke or drink during later pregnancies, which can slightly slow cognitive development. With the first child, moms tend to be extra cautious and attentive. With the others, they’re a bit more relaxed since they’ve been through it before.
These Differences Stick Around
Experts say these differences start early and don’t just fade away. By the end of their first year, firstborns are already ahead, and by the time they start elementary school, the gap remains. This explains why they tend to do better in school, land better jobs, and earn more later on.
Of course, the researchers emphasize that this study is based on statistics and doesn’t explain every family’s unique story. It shows a general trend seen in most families studied, backed by earlier research.
A 2010 study of New York siblings also found that the older sibling had a higher IQ.
Younger siblings still have hope: older research shows they tend to be more hardworking and diligent at school, which can boost their chances of catching up and building a great career. The new study didn’t explore this aspect.
