Why Firstborn Children Are Smarter Than Their Siblings

Did you know that 80 percent of people across the world are lucky (or perhaps unlucky, depending on how you think of it!) enough to have at least one sibling? We build special relationships with our brothers and sisters over the course of our lives. However, sibling rivalry is alive and well in most families — and some new research could make that competitive dynamic even worse.

According to a study conducted by economists at the University of Edinburgh and the University of Sydney, firstborn children are smarter than their younger brothers and sisters. So, no pressure for all of you middle kids and babies of the family!


Researchers examined a group of 5,000 children, beginning in utero until they were 14 years old. The findings showed that those born first in a family tend to get a higher level of education and go on to land better-paying jobs. Researchers have dubbed the phenomenon the “birth order effect.”

So what exactly were the research methods used in this 14-year experiment? Once every two years, experts tested the children’s letter-matching, reading and picture vocabulary skills. The results showed that the firstborn children in the test group tended to have a higher IQ level than their siblings by the tender age of 1.


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Other studies of this kind have reached similar conclusions. A study at the University of Essex in England found that firstborn daughters tend to be more ambitious. Need proof? Angela Merkel, Hillary Clinton, Christine Lagarde, Oprah Winfrey, Sheryl Sandberg, JK Rowling and Beyoncé are all the oldest children in their families!

Hillary Clinton photo
Getty Images | Justin Sullivan

This is all very interesting, right? The question is, how does this social phenomenon arise? Well, the researchers at the University of Edinburgh and University of Sydney give you permission to basically blame your mother and father.

Their theory is that many parents give their subsequent children the same amount of emotional support and outright love that they give to their first child. But what makes the difference for firstborn children is the time that parents spend alone with them. Why? They say it can help to instill a level of intellect that is hard to beat.


Both parents usually give undivided attention to a firstborn. This can help to give those children a slight advantage over younger children, who have to share parents’ attention from day one.

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Many parents in the study admitted that they were less enthusiastic about engaging in enriching activities with their second and third children. Like what? Well, bedtime stories, crafts and playing instruments — exactly the types of things that help to increase intelligence.

mom and baby photo
Getty Images | Ian Waldie

On top of all that, some mothers admitted that they were not as strict with themselves about things like drinking and smoking during their second or third pregnancies, which could contribute to adverse outcomes for their babies.

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If all this sounds familiar to you, and your big brother or sister is indeed smarter than you, don’t blame yourself: He or she had a scientific leg up! Your parents probably gave undivided attention to your oldest sibling. They tried to do everything perfectly the first time around.

This means that your older brother or sister may have a few more IQ points. But let’s be honest — being the middle or youngest child often means you can get away with murder! And, that’s not a bad trade-off.