I was taught birth order effects in middle school in the 2000's in the US in a "health" class (in the same unit we also did handwriting analysis). We were literally shown a video of a family in which everyone explained why they were the rebel as the second child, the overachiever as the first child, the spoiled brat as the youngest, etc. Birth order effects might exist... but even if that were true we should not teach them to middle-schoolers as determining their life. This is for the same reason that we would not want a video of a "typical community" showing a white male doctor, a white female kindergarten teacher, and a black male janitor even if all of those occupations are statistically more likely to be held by those demographics than the others. Because we live in a time and a place where children get to choose that they are not like their statistical cohort if they put their mind to it.
The only positive thing I took out of that class was the number of other students going "this is bullshit, I'm a first child and am the rebel of the family" or whatever. And it was a good introduction to not trusting authority.
The author is cherry picking studies to try and prove his hypothesis, ignoring that the "studies" he cites show only a possible correlation.
First, he's taking the results of a voluntary survey of users of his own site. He'd be better off asking a polling firm to randomly contact people, ask if they regularly read any more well-known sites that are more "intellectual" in nature, and then ask about the person's birth order.
Second, he uses anecdotal data about Harvard students, which ignores several potential sources of bias. As one example: Harvard is expensive, and students are more likely to come from families with large incomes. High-income families have fewer children. Another example: younger siblings often specifically don't want to go to the same school as their older siblings, so if an older sibling gets into Harvard, they are less likely to bother applying.
There's also a bit about males being more likely to be gay based on having more older brothers. I could probably spend an hour listing reasons you shouldn't take that research seriously.
For an effect this prevalent and strong my first reaction is "check your data." Then I read this:
>It’s unlikely that age alone is driving these results. In sibships of two, older siblings on average were only about one year older than younger siblings.
And I really start thinking you have to check your data. The average age difference in that cohort is only one year and humans have a 9 month gestation. Something is likely wrong with your data or your sample.
I would be interested to know how only children fall into this analysis. If the oldest child has more intellectual curiosity because they received more attention, you'd expect only children to have received even more attention still.
It's pretty likely that first born children were more likely to respond to the survey given that Scott openly stated he expected more first born children to be among his readership, giving people an impression that first born is better and they might feel good about themselves vs second born children who might feel bad about themselves.
I thought it was conventional wisdom that sexual orientation in males is influenced by birth order. If that's the case then I'd be surprised if there were no other effects.
There's a handful of comments kind of getting tripped up here. Scott is relying on a 1-2 punch-- First, that openness to experience was decently different in the two groups (73rd percentile vs 69 percentile) and then that most Big5 tests aren't done well. (
Big5 is a valid personality test-- it gets decent test/re-test scores, but it's still weak. Myers-Briggs fails because, despite being very similar to the Big5, it doesn't have good enough test/re-test scores.)
Scott cites another study that says when you test openness properly, you get a wider distribution. So if you pair those two together, you get a decent sized effect. Maybe.
This doesn't seem to be a "birth order" effect, so much as a "first born" effect. Once you get past the first child, there doesn't seem to be much influence. That makes me very skeptical of any biological explanation, as you would expect to see more of a tail-off.
I think it's more likely a measurement error, or some subtle statistical effect caused by a combination of probability skewing and demographic changes.
There is also a disproportionate amount of people online that are born jan 01 1900, and have mothers with the maiden name "asdf". Several thousand % more than you would expect.
Reading a random person rant about scientifying stuff, should perhaps be evenly distributed across siblings; until you realize that writing style does give away a lot about the person writing it. You can write a decently performing classifier that predicts gender (and several other demographics) from stuff they write, even from tweets, and chats. It would be stupid to think that people do not pick up the demographic clues in writing, and set their preferences accordingly.
This doesn't seem like a valid approach to me. To take a specific group, measure something, and assume that metric had an impact on them being in that group.
It's interesting nevertheless.
The birth order effect is fascinating to me because my bias is to trust the scientific consensus, but as a parent I see such obvious patterns in my children and in the dozens of friends kids that I’ve watched over the years.
It’s hard to reconcile.
It's odd to discuss this without also mentioning the very strong apparent affects of birth order on sporting ability, eg .
I'd never heard of the supposed higher intelligence of first born, but I've heard a lot about the sporting side and anecdotally I've noticed it too (I am the oldest sibling in my family).
> But these demand strong effects of parenting on children’s later life outcomes, of exactly the sort that behavioral genetic studies consistently find not to exist
Would like to hear more details to that claim. When ever I read about genetic factors (For example on the topic of depression), I keep hearing that without the environmental factors the genetic indicators loose their predictive power. Genetic factors in behavioral science make a person more effected by environmental factors, but alone the genetic factor tend to have no effect.
To take the explicit example in the article. Is there an measurable effect in adult life that correlate to the amount parents focus and dedicate time to them as child? In rats I have heard enough studies to show a very strong correlation between stress in adult life and time that the rat got groomed as young by the mother. Could it be so simple that parents spend a bit more time/focus with the first child during the first few years, while the second child receive a bit less since there is now two children and the parents are a bit more experienced and feel more secure in parenting. While rats and humans are not identical, it is a strong hint that "parenting style" might carry an effect into adult life.
Although heritability estimates are significantly greater than 0%, they are also significantly less than 100%. As noted earlier, heritability estimates are substantial between 30% and 50%.... No traits are 100% heritable (e.g., Plomin, 1989; Turkheimer, 2000).
Speaking informally, but as a professional analyst here who is unfortunately at a computer with no analysis tools setup :( but who has worked with his fair share of social, survey and demographic information.
Check your data. My first gut-instinct on seeing data like that is not "Eureka - i found a huge first-birth-order effect", but rather "huh...looks wrong, I wonder why that is?".
What do I mean "looks wrong"? Keep in mind I have no real "pony in the race" on first-born effects (although I admit I am one), but intuitively it "doesn't look like real social data looks like".
The effect is too big. Its too loud. Its too constant. Its too nice. Something else is driving it and its your job to find out what...
The first place I'd look is data quality. Have you proven your data got into your final histogram data set right? I had problems with your csv opening it in libre office...looks like it interpreted it as having some value migration between the variable in whatever you did. Could be my computer, but in my experience, if there's a problem with the csv, these kind of things correlate with other mistakes.
The second place i'd look is survey design: was there a default option, are people clicking through by default, are the response frequencies of other variables lining up as would be expected (gender, birthdays, that kind of thing). If not, why not?
If you've crossed and ticked all those, only after that would I start the analysis...but again, a pattern and effect of that size and consistency is something that you should default to needing explained in the data. Reach the conclusion that its real only after you've eliminated everything else.
To me it seems most likely that it is entirely due to environmental/nurturing reasons rather than some innate effect of being first out of their mother. For example money for school can vary, and the parents attitude towards nurturing thier children definitely does.
Found the aggerate survey data:
And it is pretty obvious the sample is bias, though take a look to see for yourself and comment if you notice anything too.
Anyone else find it strange that the author used SAT scores as a metric for intelligence? I think it is kind of absurd to think that a test that is specifically not designed to test intelligence and designed to give trick or misleading questions is a good metric. Not to say there isn't a decent correlation between intelligence and test scores, but a significant amount of people fall through the cracks. From what I understand, even the academic communities don't place a lot of weight on tests like SAT, ACT, GRE, etc. I think it is fine to use this method to measure intelligence, but not in isolation.
"I first started thinking this at transhumanist meetups, when it would occasionally come up that everyone there was an oldest child."
Alternative hypothesis: first-born children wish to escape their siblings so much that they would prefer to leave the species.
> It’s unlikely that age alone is driving these results. In sibships of two, older siblings on average were only about one year older than younger siblings. That can’t explain why one group reads this blog so much more often than the other.
It would be interesting to investigate the relationship between the age of the respondent and the effect of birth order. For example, does birth order matter less for millennials than it does for baby boomers, or vice versa?
Also would be interesting to investigate how much the age difference between siblings matter. For example, does birth order matter more if the siblings are born 1 year apart vs 10 years apart?
Not an issue with this study, but possibly worth noting that, naturally, there must be more firstborns than subsequent-borns (not counting the generic middle-child grouping). This could lead to a larger preceived effect.
Few things helped me more understanding people and family than knowledge of birth order.
First born, middle, baby, only... Quite helpful as how to understand and predict people's actions. And how to communicate with them.
Also, the cases where the first born or first son being expected to behave like a FB but are naturally not...often they dont realize this until adulthood.
The book by Leman (The Birth Order Book) i bought shortly after entering the workforce. A great read.
For those interested in the topic, I can recommend Judith Rich Harris' superb book, The Nurture Assumption.
It mostly deals with debunking common views on parent->child effects, but includes some material on birth order effects.
> It’s unlikely that age alone is driving these results. In sibships of two, older siblings on average were only about one year older than younger siblings. That can’t explain why one group reads this blog so much more often than the other
So, uh... People understand that "average difference" is a miserable plan here right?
The reason is probably that the first child gets the most attention, right?
There are some articles on HN about boredom and creativity. Perhaps its just that firstborn have more time alone. It'd be interesting to see age differences vs creativity.
For me, the movie Gattaca perfectly captures the importance of nature vs nurture. The equalizer is how one responds to adversity.
Wow, I'm impressed that the average IQ of Scott's readership is so high (at least if you use SAT as a proxy for IQ).
Didn't he also run a control condition on Mechanical Turk? Why isn't that analyzed here to show the effect?
Not convinced. What about the effect of selection bias? That done probably accounts for the entire "study"
I’ve often thought that certain jobs should only be open to first borns. Jobs with serious responsibilities.
Sure they exist, but we don't want to talk about it. There is a strong motivation to be able to say that everyone is created equal, regardless of how uncontrollable factors affect you (birth order, height, race, gender). We don't want to kill someone's motivation to study for college just because they are a third child. But stereotypes exist for a reason. The hard part is separating hatred-based stereotypes from the stereotypes based on observations throughout history.
Regarding birth order, the "middle child" stereotype is prevalent in Western society. Did the middle child stereotype spring from some sort of effort by first-borns to keep their lower-ranked siblings in line (a la racism?)? I doubt it. The middle child stereotype probably came from hundreds of years of observations. It's a similar story for the first-born and last-born stereotypes- they weren't created out of any prejudice, but probably from hundreds of years of mothers chatting about their kids.
Like the article says, denying that the differences exist prevents us from ever finding out why (because people won't do research on something that doesn't exist). So let's acknowledge that some groups of people are different than other groups, and then respectfully do research to figure out why. The differences could be societal- perhaps first-borns are treated with more care by their parents, or they could be biological- perhaps the hormonal changes in a pregnant woman are different for each successive child, or they could be something else entirely- I had many of the same teachers as my older sister, and I often benefited from them having a pleasant experience with her, making my time in class much easier.
But anyway, the first step is acknowleding that a difference exists, and that you aren't somehow "birth order-ist" just because you acknowledge that first-born kids often outscore lower order kids on many metrics.
intellectual curiosity != slatestarcodex reader
Middle child here.
I didn’t like the methodology of this study, so I did my own little study, my wife being the core respondent.
The results were astounding and the P value is off the charts (higher is better in this case - trust me).
Conclusion: middle children are the best
This article is going to be flagged into oblivion into a few hours. We're not discussing the relationship between biological and psychological traits on HN.
Wierd, I'm the youngest of 6, and I'm acknowledged by the others as the smartest of the lot, by quite a margin. "bloody little genius" has been my nickname since I'm about 8 ;-)
My older brother was as smart as a box of rocks. Even given that, he was an under achiever. He would couch surf and mooch off anyone. He would work a job until the first pay check then quit. If there was ever a reason to be against UBI, he was it. I would tell my mom he's like that first pancake that just doesn't turn out right because you rushed.
I, on the other hand, became an engineer.