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Higher IQ and Firstborns — The Real Story

As many news organizations reported this past week, a study on 241,000 Norwegian 18- and 19-year-olds found a small difference in IQ, which the researchers attributed to family dynamics, not biological or genetic differences.

And that’s the key take-away from the research. Not, as most media organizations are headlining that “First Born Have Higher IQs.” Because, while factually true, the headline is completely misleading. A 3 point difference is not clinically significant, certainly not significant enough to have life-altering effects or differences one could even notice in day-to-day life.

The New York Times claims otherwise, citing unnamed “experts” who say it can be a “tipping point for some.” Well, first, who says this? What psychologist would claim that a 3 point difference in IQ is going to make that significant a difference in a person’s life that it could alter their educational options and choices for all time? I just find it incredible to believe, since it goes against everything I’ve read, was taught, and know from my colleagues who work with IQ day-in and day-out. Except in some rare case, there is no significant difference between someone who scores an IQ score of 100 and one who scores a 103. (The standard deviation for most IQ tests is 15 — meaning you need to get to 85 or 115 before people are really seen in a different light for their “smarts” or abilities.)

Now, the confusion likely arises because the researchers point out that this 3 point difference is significant. But they are talking about statistical significance in their research design. There is no clinical significance to a 3 point difference in this range.

And that’s where the mainstream media is getting this story completely wrong.

The real significance of this study wasn’t in the 3 point difference, but in the fact that the study teased out whether this was genetics or not, without actually having to look into people’s brains or genes. If it was genetics, then a second-born would be expected to have second-born IQ (100) no matter what. But in cases when the first-born dies, the second-born’s IQ raises up to the first-born’s IQ (103).

Now that part of the study is really interesting, because it shows how significant the family and social situation really impacts our learning abilities. That’s it’s not written anywhere, “Well, since you are second-born, you can’t be as good as Joe Firstborn.” In fact, the study is a boost for people who believe that family dynamics and family upbringing really make a difference (for better or for worse) in a person’s development and abilities.

Higher IQ and Firstborns — The Real Story


John M. Grohol, Psy.D.

Dr. John Grohol is the founder and Editor-in-Chief of Psych Central. He is a psychologist, author, researcher, and expert in mental health online, and has been writing about online behavior, mental health and psychology issues since 1995. Dr. Grohol has a Master's degree and doctorate in clinical psychology from Nova Southeastern University. Dr. Grohol sits on the editorial board of the journal Computers in Human Behavior and is a founding board member of the Society for Participatory Medicine. You can learn more about Dr. John Grohol here.


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APA Reference
Grohol, J. (2018). Higher IQ and Firstborns — The Real Story. Psych Central. Retrieved on October 17, 2019, from https://psychcentral.com/blog/higher-iq-and-firstborns-the-real-story/
Scientifically Reviewed
Last updated: 8 Jul 2018
Last reviewed: By a member of our scientific advisory board on 8 Jul 2018
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