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Boys at the top of the pecking order -- either by birth or because their older siblings died -- score higher on IQ tests than their younger brothers.
The question of whether firstborn and only children are really smarter than those who come along later has been hotly debated for more than a century.
Norwegian researchers now report that it isn't a matter of being born first, but growing up the senior child, that seems to result in the higher IQ scores.
Petter Kristensen and Tor Bjerkedal report their findings in Friday's issue of the journal Science.
It's a matter of what they call social rank in the family -- the highest scores were racked up by the senior boy -- the first born or, if the firstborn had died in infancy, the next oldest.
Kristensen, of Norway's National Institute of Occupational Health, and Bjerkedal, of the Norwegian Armed Forces Medical Services, studied the IQ test results of 241,310 Norwegian men drafted into the armed forces between 1967 and 1976. All were aged 18 or 19 at the time.
The average IQ of first-born men was 103.2, they found.
Second-born men averaged 101.2, but second-born men whose older sibling died in infancy scored 102.9.
And for third-borns, the average was 100.0. But if both older siblings died young, the third-born score rose to 102.6.
Social rank, not birth order
The findings provide "evidence that the relation between birth order and IQ score is dependent on the social rank in the family and not birth order as such," they concluded.
It's an issue that has perplexed people since at least 1874, when Sir Francis Galton reported that men in prominent positions tend to be firstborns more often than would have been statistically expected.
Since then, several studies have reported higher intelligence scores for firstborns, while other analyses have questioned those findings and the methodology of the reports.
While the Norwegian analysis focused on men, other studies have included women, some indicating a birth-order effect and some not.
Frank J. Sulloway of the Institute for Personality and Social Research at the University of California, Berkeley, welcomed what he called the Norwegians' "elegantly designed" analysis.
"These two researchers demonstrate that how study participants were raised, not how they were born, is what actually influences their IQs," said Sulloway, who was not part of the research team.
The elder child pulls ahead, he said, perhaps as a result of learning gained through the process of tutoring younger brothers and sisters.
The older child benefits by having to organize and express its thoughts to tutor youngsters, he said, while the later children may have no one to tutor.[/b]
It's very interesting. I've read the book "Growing Up First Born" and it talked about this too. I'm the oldest of 4 so I can't deny that I'm a genius anymore!
Well, they're saying the *average* score. The difference on a case-by-case basis can be much more noticable.[/b]
I understand it is an average...I guess I am wondering how many people were tested in this study. The smaller the number, the more likely that there wasn't any great difference between the two groups (first born and subsequent children).
But if it was a bigger study, then I guess you could have some pretty significant variations, and still have the average be 2 or 3 point difference.
But, why the vast (if it was a bigger study) variations in the first place?
ETA: What about the lack of consistency (IMO) if there are such vast variations? Lack of consistency (IMO) always leads me to believe that the results are more of a product of chance, rather than fact.
The difference in the scores (103.2 vs. 101.2 vs. 100 for the third-borns) is so tiny, it hardly matters. An even 100 is average. 112 is the next standard deviation up, meaning that the distance is statistically significant from 100. So basically anyone within the 100 to 111 range is considered an average IQ and more or less equal to one another as the scores can change within a range of points each time a person takes the test.
However when you have a large study population you should always get an average IQ of 100, as they did with third-borns here. Any statistically significant difference in IQ from the average of 100 does mean something. The fact that the research shows a consistent though very tiny difference tells me that first-born children are probably getting something extra, maybe it is their parents' time or attention, maybe they are talked to more, maybe it is all the brand-new toys. It seems we kinda already knew that firsts and onlies had a few advantages in those areas...
The difference in the scores (103.2 vs. 101.2 vs. 100 for the third-borns) is so tiny, it hardly matters. An even 100 is average. 112 is the next standard deviation up, meaning that the distance is statistically significant from 100. So basically anyone within the 100 to 111 range is considered an average IQ and more or less equal to one another as the scores can change within a range of points each time a person takes the test.
However when you have a large study population you should always get an average IQ of 100, as they did with third-borns here. Any statistically significant difference in IQ from the average of 100 does mean something. The fact that the research shows a consistent though very tiny difference tells me that first-born children are probably getting something extra, maybe it is their parents' time or attention, maybe they are talked to more, maybe it is all the brand-new toys. It seems we kinda already knew that firsts and onlies had a few advantages in those areas...[/b]
I have more than a few siblings, half and step, but was raised as an only.. so of course I have no way to compare myself to my sibs
however I am agreeing with Kyle (and I was going to post some of the same info cause I'm studying stats RIGHT now for my NCE)
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The difference in the scores (103.2 vs. 101.2 vs. 100 for the third-borns) is so tiny, it hardly matters. An even 100 is average. 112 is the next standard deviation up, meaning that the distance is statistically significant from 100. So basically anyone within the 100 to 111 range is considered an average IQ and more or less equal to one another as the scores can change within a range of points each time a person takes the test.
However when you have a large study population you should always get an average IQ of 100, as they did with third-borns here. Any statistically significant difference in IQ from the average of 100 does mean something. The fact that the research shows a consistent though very tiny difference tells me that first-born children are probably getting something extra, maybe it is their parents' time or attention, maybe they are talked to more, maybe it is all the brand-new toys. It seems we kinda already knew that firsts and onlies had a few advantages in those areas...[/b]
So, I'm not a genius?
[/b]
No, you're still a genius LOL!! This is all completely on the broader, averaged-out scale. Like a first-born in the study could have an IQ of 96, his second-born brother could have an IQ of 105 and the third-born might be 111. Because each child was averaged with other children of his birth order, the individual scores get absorbed into the averages regardless of whether they individually actually followed the overall pattern. So go get down wit your bad genius self!!
The difference in the scores (103.2 vs. 101.2 vs. 100 for the third-borns) is so tiny, it hardly matters. An even 100 is average. 112 is the next standard deviation up, meaning that the distance is statistically significant from 100. So basically anyone within the 100 to 111 range is considered an average IQ and more or less equal to one another as the scores can change within a range of points each time a person takes the test.
However when you have a large study population you should always get an average IQ of 100, as they did with third-borns here. Any statistically significant difference in IQ from the average of 100 does mean something. The fact that the research shows a consistent though very tiny difference tells me that first-born children are probably getting something extra, maybe it is their parents' time or attention, maybe they are talked to more, maybe it is all the brand-new toys. It seems we kinda already knew that firsts and onlies had a few advantages in those areas...[/b]
TO the bolded: Really? LOL, not the case for me! The baby got all of the attention, followed by the only boy, and then...me! HAHA!
The difference in the scores (103.2 vs. 101.2 vs. 100 for the third-borns) is so tiny, it hardly matters. An even 100 is average. 112 is the next standard deviation up, meaning that the distance is statistically significant from 100. So basically anyone within the 100 to 111 range is considered an average IQ and more or less equal to one another as the scores can change within a range of points each time a person takes the test.
However when you have a large study population you should always get an average IQ of 100, as they did with third-borns here. Any statistically significant difference in IQ from the average of 100 does mean something. The fact that the research shows a consistent though very tiny difference tells me that first-born children are probably getting something extra, maybe it is their parents' time or attention, maybe they are talked to more, maybe it is all the brand-new toys. It seems we kinda already knew that firsts and onlies had a few advantages in those areas...[/b]
So, I'm not a genius?
[/b]
No, you're still a genius LOL!! This is all completely on the broader, averaged-out scale. Like a first-born in the study could have an IQ of 96, his second-born brother could have an IQ of 105 and the third-born might be 111. Because each child was averaged with other children of his birth order, the individual scores get absorbed into the averages regardless of whether they individually actually followed the overall pattern. So go get down wit your bad genius self!!
[/b]
It makes sense....I'm just an exception to the rule!
The book "Growing Up First Born" is really interesting, though. It only talks about IQ's briefly. The whole book is just about how first borns are treated and the differences between first born and middle child, etc. I really could relate....
Wait, for Kyle: OK, so first borns get an extra *something*. Does that mean the scores go down for all subsequent children then (i.e., in something like the Duggart family, would the 14th child have that different of an intelligence level than the 1st?), or the first is just generally more priviledged and the rest are about even?
Hmmm.... that seems like such a tiny difference that it isn't even worth mentioning IMO. I am the firstborn in my family (though I do have two half siblings who are older) and I have always done better in school than my younger siblings. I don't know if there's any correlation in that or not... but we all did take IQ tests when we were in high school, and my brother (the youngest) actual scored the highest, but we were all over 140.
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Yeah, thats such a small number, and middle children are more stressed out from thier siblings that they could have just been too stressed for the test. Its all to miniscule to even make an issue of.
The social order theory makes sense to me I suppose as a favored child, first borns and only children might get more involvement from their parents in their preschool years. But, as Kyle mentioned, unless we are talking about differences a standard deviation above or below what is normally expected, I hardly think it is worth getting worked up about. A score of 103 and 100 isn't that huge and if they tested them on a different day, they could come out with the same scores or the person that scored the lowest might score the highest. I think I remember research stating that only in family's with more than 10 children do the youngest children start to suffer academic impairment but that was years ago and who knows what kind of studies have been done since then.
Wait, for Kyle: OK, so first borns get an extra *something*. Does that mean the scores go down for all subsequent children then (i.e., in something like the Duggart family, would the 14th child have that different of an intelligence level than the 1st?), or the first is just generally more priviledged and the rest are about even?[/b]
I have to believe that the firstborns are getting some tiny little benefit that the others aren't. The reason I say this is because when you have a study sample of over 400,000 people based on a characteristic that is not known to relate to intelligence (such as birth order, or for that matter eye color or height), you expect an average IQ of exactly 100. The average IQ has been set at 100 in order to reflect that that exact level of intelligence is historically the average when you test any large population. So the fact that the firstborns had an average of *very slight and not statistically significant* 3 points above the average tells me one of four things:
- there was general sampling error despite the large sample studied, which has a very low probability of occuring
- there are more (or more extreme) outliers in the firstborn sample. For example, let's say there were 150,000 firstborns; 150,000 secondborns; and 150,000 thirdborns. And let's say that among the firstborns there were 300 certifiable geniuses (IQ over 140) while in the secondborn sample there were 250 and in the thirdborn sample there were 200. The extra 50 to 100 outliers in the firstborn group *could possibly* raise the average IQ a few points higher even though if the extreme outliers in all categories were eliminated then all three groups might have an average of 100. Sampling error is much likelier to happen in the smaller subset of geniuses than on the larger scale that says all firstborns are 3 IQ points higher than all thirdborns.
- Similarly there could simply have been more extremely low-IQ persons in the thirdborn group which could cause the numbers to possibly work out in the other direction. If that was the case, then you'd have to look at confounding factors such as the parents might be older at the birth of their third child and have a higher rate of Downs Syndrome etc. based on that factor and therefore IQ would not be based on birth order at all, but rather on age of parents. In this case however, you would have to assume that the population of Norway as a whole have an average IQ of 103.2, and several OTHER confounding variables would need to be considered in that case.
- the final possibility is that there really IS some benefit to being the firstborn, which results in a tiny, statistically insignificant but consistent benefit of 3.2 IQ points. If that's the case there could be any number of reasons related to birth order, such as having more undivided attention from parents. On the other hand, on a common-sense level you might also argue that second and thirdborns IQ SHOULD benefit in other ways such as having an older sibling to expose them to learning, interaction with older siblings who have better language skills, and possibly more (and more advanced) books, computer programs etc. in the home due to having an older sibling.
The main things to keep in mind about ANY research are:
You cannot infer causation from correlation. Just because two things show up together in a study does NOT mean one caused the other.
-AND-
Studies cannot predict individual cases. So this study absolutely cannot predict whether you as a firstborn really will be smarter than your younger sibling, because these numbers are only averages and there are certainly many cases where younger siblings are smarter than the older siblings, for any number of reasons. And I have no idea about the Duggar family because there are many extraneous variables in that case just as there are in any individual example. For instance, maybe every one of their kids is smarter than the one before because the parents are perfecting their homeschooling skills with the older ones and are better able to teach the younger ones. KWIM?
My brother is two years older than I am, and he is only "above average". (for instance, on his ACT, he scored a 25 when the average is 22).
I, on the other hand, score in the top 2 percentile for people in the united states.
My mother drank no caffeine with either of us, ate all of the right things, didn't smoke, stay on her feet too much, or get near alcohol.. so it's definitely nothing to do with environment. If anything, I would assume she was more careful with Bob because he was her first child. We are biologically brother and sister, as well. (instead of half or step)
Now, this isn't to say that it means anything.. it could just be a fluke. Personally, I'd just like to think that girls are way better = )
(and if my mother being so careful with what she put into/allowed near her body during pregnancy mattered even in the slightest, what will that mean for my baby? I'm not around smoke, and I don't drink.. but I do have about 3 cokes a week. hehe.. oops.)
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