How Birth Order Affects IQ And Personality
If you’ve grown up with a sibling, you’ve likely heard about how birth order can affect any number of things.
Academic rivalries, risk taking tendencies, intelligence, and exerting self-control are just a few of the attributes that have been associated with being born first, second, or third.
A massive new study looked at over 377,000 kids to see if birth order had any links to differences in personality or IQ. The results might not be what you expected.
Getting It Right
If 377,000 kids seems like a lot, you’d be right. It’s the largest study ever done in regards to looking at differences when it comes to birth order. The details of the study were published in Journal of Research in Personality.
The researchers also went to lengths to make sure they got it right. Doing so required doing things a little different.
Some studies suffer from small sample sizes. While this is done to keep research costs low, it can skew results. Some effects can be exaggerated which makes the results unreliable.
The study also looked for confounding factors. These are variables that scientists look for that might affect the results. One of the factors accounted for in this study was economic status. This is done because it is known that wealthier families generally have fewer kids. Why does this matter?
First-borns in wealthier families generally have more access to resources. This has been found to affect IQ and personality. So scientists wanted to make sure this wasn’t impacting the results.
Another problem is accounting for the relative age of the children. Generally speaking, older children have had more time to develop. When comparing children this becomes an issue. If you compare an older child with a younger child, they are going to appear more responsible because they’ve had more time to develop those skills. It’s an unfair comparison that is done in some studies.
They also adjusted for other factors that had been ignored by previous studies. Additionally, the scientists made sure to measure each child’s personality on an individual basis to make the data as accurate as possible.
Results Are In
Here’s what the researchers found.
First-borns were found to have a 1 point increase in IQ over their siblings.
There were also some differences in personality. Those who were born first tended to be more extroverted, agreeable, and conscientious. They also had less anxiety than children who came after them.
If you think that is the end of the story, you’d be wrong. The researchers made sure to put their results in the proper context.
How Much Does It Matter?
Although their findings were significant in statistical terms, you should be asking another question. Would you be able to see the difference?
The scientists argue that you can’t.
In fact, the differences are small enough that it’s meaningless. The lead person who did the analysis – Roberts – had this to say:
“In some cases, if a drug saves 10 out of 10,000 lives, for example, small effects can be profound. 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.”
So even though there are differences, it’s not enough to raise any eyebrows. One point in IQ doesn’t mean much, and child personalities are generally going to be the same.
As far as raising your kids? It makes sense to treat them equally.
Damian, another researcher from the study, put it well:
“The message of this study is that birth order probably should not influence your parenting, because it’s not meaningfully related to your kid’s personality or IQ.”
So in the end, you probably shouldn’t worry about birth order.