Firstborn children are the cleverest
19:00 21 June 2007
NewScientist.com news service
Roxanne Khamsi

Science magazine
Intelligence journal
Firstborn children score significantly higher in IQ tests than their younger siblings, according to a large study of 250,000 military draftees in Norway.

The researchers say the difference is due to social, not biological, factors, as younger siblings have higher IQs if they are raised as an eldest child following the death of an older brother or sister. The findings could suggest better ways of parenting the youngest children in a family.

Petter Kristensen, at the University of Oslo in Norway, and colleagues reviewed data collected from 18- and 19-year-old men drafted into the country's military between 1985 and 2004. These young men took intelligence tests as part of their compulsory military service.

Researchers then looked at the Norwegian birth registry to determine whether these men had older or younger siblings. Medical records also indicated whether their siblings had died shortly after birth, or at a relatively early age.

Decreasing IQs
The analysis revealed that firstborn men have, on average, an IQ that is about 2.3 points higher than those who are second-born. The trend continues such that second born men have higher IQs than their third-born brothers, and so on.

In the US, SAT exams in reading and mathematics have a combined total of 1600 points, and on these two sections a difference in IQ of 2.3 could mean a 30 point difference in scores, says Frank Sulloway, at the University of California, Berkeley, US. This can mean the difference between getting into a premier university or second-tier university in the US, he points out.

A further review of about 600 families that included at least four children showed that the eldest sibling typically has an IQ that is 2.9 points higher than the fourth-born sibling (Intelligence, DOI: 10.1016/j.intell.2007.01.004).

Sulloway calculates that a 2.3 IQ score difference means that the eldest child has a 13% higher chance of having above-average intelligence than the second-born in their family.

The new research shows that it is social birth order – and not actual birth order – that really matters: a person whose older sibling died at a young age generally has a 2.3 point higher IQ score than other second-born individuals.

Time investment
Sulloway explains that older siblings might have a higher IQ because they act as surrogate parents from time to time, tutoring their younger siblings in certain situations.

Another possible explanation is that parents have more time and resources to invest in their firstborn child. As a result of this, the eldest child usually has the most one-on-one time with its parents, and receives greater exposure to their sophisticated vocabulary.

Parents might be able to boost the IQs of younger siblings by scheduling in more individual time with them, Sulloway speculates.

Kristensen, who is the second-born child in his family, says his other three siblings have differing views about his new findings. "The person who is happiest about the results would be my older brother," he says. As for his younger siblings, "they just don't believe it".

He notes, however, that older siblings are much more likely to have a low birth-weight and die in infancy their younger counterparts.

Journal reference: Science (DOI: 10.1126/science.1141493), Intelligence (DOI: 10.1016/j.intell.2007.01.004)

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wow I just read that last line. I am the oldest and actually the cleverest and was born prematurely at 7 months at 3.6 lbs ( which was scary back in 66. ) and yeah I had to take care of all my siblings.

Hmm, I have an older brother...guess that's whay some of my replies on UM read like a moron wrote them.

I was the last born in my family. My IQ is far above anyone else in the family, and I was a member of Mensa.
Statistics can be made to support nearly any conclusion, regardless of how ridiculous it might be.

I have one problem with that statement which I did see on the news. Is there really such a word as "cleverest?" Would it not be "the older child is the most clever?" I would say whoever wrote that, was not the oldest child LOL

I am the oldest but my sister , the baby , always got higher grades , but any family member would say I was smarter and I don't think that's true.

remember there is book smart and life dumb. as a neighbor used to say. I wouldn't say really I'm smarter than my sister because I'm not , but what I am is quicker. I think my sister is just as smart

I knew a kid who belonged ( still belongs ) to Mensa. book smart . life dumb. an emotionally desolate man always having to make sure all were aware how smart he was. But he is an emotional cripple.
Alot can be said for one's EQ.

I wouldn't agree with that, I think it depends on the circumstances. I have an older sister and I'm far more clever than she is. I attribute this to the fact that I've always loved reading, never went anywhere without a book, and just generally loved to learn (spent my time watching documentaries, loved museums and history, always asking questions) whereas my sister always had stars in her eyes, and spent most of her time in acting and modelling classes, never paying attention at school because she was "going to be a star" and didn't need an education (her reasoning). Naturally I did far better than she did in school, and even now she constantly asks me questions or help in explaining something to her, but I don't mind cause I love getting my nerd on

Lt., my elder brother has an above average IQ, sister likewise. Neither is even close to mine. Moreover, the two eldest children have lesser numbers, but are far more practically oriented than #3 and #4. Going beyond that, while #5 (me) has the highest IQ, he also has the greatest degree of both common sense and practical experience and capability than any of the others. #1 can work on cars, paint, fix plumbing, etc. #2 is approximately the same. #3 has a Master's degree, but couldn't change a spark plug and must call a plumber to unclog a toilet. #4 has a Master's and writes novels, teaches, and so on, but couldn't change a spark plug or assemble the major parts of a computer or unclog a drain, basically the same as #3. #5 has a Master's, has written papers in his field, has owned and operated an automotive repair business, has rebuilt entire plumbing systems, electrical systems, built smaller-than-house structures (but is certain he could build a house sized structure), painted, rebuilt insides of houses, and so on ad infinitum.
In essence, then, the first two are worldly capable, the second two are book capable, the last is both.
As stated, statistics are unconvincing.

No wonder I'm the stupidest out of all the kids my mom had.

I agree that the statistics are unconvincing....My oldest daughter weighed 5lbs at birth...She carried a 4.0 average throughout high school and college, but it didn't come easy for her...She was constantly reviewing her texts....My middle child, had to apply herself constantly just to pass...Now my youngest, my son, has a photographic memory, and seems to be the smartest of all three....They grew up unique in their own way, and I now see the same pattern with my grandchildren...

In times like this I'm glad I'm an only child.

You have it all.....

Well, I'm the third out of four, and I can say that my older brother (child #2) is quite intelligent, and he'll tell you all about it. My eldest sister is most definitely NOT the most intelligent, not that she is dumb, but not that great in both real life and books, just average. I now that I had the highest IQ in the tests that we did in high school, OK, there were only like 30 of us in high school, but the counselor who got the results walked up to me in front of everyone and told me I HAD to go to college, not to waste what God gave me (that went over well with the "smartest" guy in high school! If he didn't hate me before, he sure did then) My youngest sister had the hardest time in school, but yet she was the one who graduated from college first. She works hard at everything in her life and if you want to know anything medical, she can tell you, once she learns, she remembers.

Now, I was born 6 years after my mom had my big brother, so her body had a lot of time to recuperate after giving birth to two babies within three years. I wonder if they take that into account? Babies born too close together will tax the mother's body and of course the younger one will get teh short end of the stick. Maybe they should check in with those families that the mom's space their children apart?

not true my brother is mentally challenged..

Hmmm... my younger brother is much smarter than me. Not that I'm a slouch mentally, but he's way smarter.

I can believe that the oldest child might be different in some way. The oldest child is continuously creating the definition of what it means to be ___ years old in his or her family. I can imagine that the oldest child might be more stubborn in the face of opposition. But I don't believe birth order affects IQ. I guess I also don't believe in the value of IQ tests.

I think reading has a lot to do with it as well. My oldest is street smart, my middle child I think will blow him away as he gets older, my youngest it a total idiot (toilet paper nose kid)

I also think that the more kids you have the more exhausted you get as you go along.

When breakfast cereals become a legitimate dinner option for you as a parent, you might have too many kids.

LOL SMK


BTW....that is so NOT true!!! Sheesh!!!

Hmmm, I have to disagree with this.

What if the eldest son is developmentally disabled? Not disussed.

What if you're the youngest and outscore the whole family?

An IQ test is just a load of crap (IMO) not fully defining the inteligence of a person through verbal interviews.

As I've said before, some of the dumbest people I know are in Mensa. Why? They totally lack common sense and/or street smarts. There needs to be a way to factor this into the test; don't you think?

I think each IQ test I've taken is BS and I wouldn't place much validity on the numbers. It cannot completely define the human's character. When the above is incorpoated into the test then maybe the score would be a more valid way to compare individual's.

Hoo-rah!!

Oh man, you nailed that on the head! LOL. Thank god for Frosted Flakes!


I have a younger brother... I dont know if thats neccaserially true?

What do you mean by clever, becuase im the first born and im crap at school, but with mysteries and stuff, i know and understand very complicated things which is wierd.