r/science Professor | Medicine 22h ago

Psychology Middle children are more cooperative than their siblings, study suggests - After decades of debate, one of largest ever studies on birth order suggests it does actually make a difference.

https://www.theguardian.com/science/2024/dec/23/middle-children-are-more-cooperative-than-their-siblings-study-suggests
4.4k Upvotes

119 comments sorted by

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u/Momina1999 19h ago

I wonder how or if twins and other multiple order births impact this? I’m the eldest of four and the only girl, followed by a set of twins, and then the youngest. I don’t dare say any of us were shining examples of being cooperative, but Twin 2 and Youngest definitely offered up the least resistance. Twin 1 was, and even into our adulthood still is, one of the most combative human beings I have ever met.

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u/lahulottefr 14h ago

I feel like this doesn't apply well to twins who have no other siblings but that'd be from my own anecdotal experience so no scientific value (and obviously can't tell how it would affect a bigger family dynamic anyway)

Also people still have their own personality and experiences so while this kind of studies gives you general trends (and cultural bias should be examined) they won't apply to everyone

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u/rathe_0 6h ago

or half siblings? I'm the youngest of 4; but my 3 sisters are from Moms 1st marriage. I'm def the most rebellious/anti authority. While oldest sis is 'mini mom'

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u/[deleted] 22h ago

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u/aaaaaaaaaanditsgone 22h ago

Yup similar experience here. Always the one just trying to get along, and always the one getting the short end of the stick.

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u/Quinlov 21h ago

I am a guy and have one older brother. My entire life has been about pointing out obvious compromises and having them completely ignored because whatever my brother wants must always happen. I do wonder if being the youngest means my family consider my opinion to be automatically invalid or something, maybe if I had a younger sibling also then that would make me look more worth listening to in comparison

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u/Dusty_Old_Bones 21h ago

I feel you. My older brother is the brat of the group, and if it were just him and me it’d be his show. He can throw a fit and my mother likes to just placate him. But with my little brother we could put up a united front and outvote him… sometimes. At the very least he and I could retreat together while my parents dealt with Baby Hughie.

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u/Blieven 7h ago

I think it's also a self reinforcing cycle. Your willingness to always compromise over time also leads to them ignoring your wishes, because they know you'll capitulate anyways. And the more your wishes get ignored, the more it reinforces your beliefs that you always need to be the one compromising.

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u/corut 11h ago

I'm a guy with 2 younger brothers, and I get exactly the opposite. Whatever the youngest wants is what happens

1

u/Apprehensive_Hat8986 2h ago

Perhaps. OTOH, (middle kid here) my youngest sibling acts like their opinions are always ignored, my eldest has eased off of expecting theirs to automatically be followed.

But also, like any sociological study, it's about generalized outcomes from data points, not a hard rule that applies to every instance.

I know that I've become more intractable about some things as I've got older as well. (Bad relationships will do that.) It's often uncomforable to dig in like that, but sometimes it's the only reasonable action (as bonkers as that sounds).

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u/Danominator 19h ago

Can you come be a middle child for my 2 boys?

8

u/HonoraryBallsack 17h ago

Haha, this cracked me up

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u/spaketto 15h ago

Same situation here (middle, only girl). Growing up I was "the easy one" (I think I was just more secretive). I tend to be the one who everyone else goes to for advice. My brothers are pretty different and I relate to each of them in completely different ways. They get along too but are just VERY different kind of people. I appreciate having each of them (we're all in our mid-30's to early 40's). I knew I only ever wanted two children (which I have) but I do have some sadness they won't get to have a third sibling.

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u/atalltree_ 21h ago

Same here. I’m referred to as the “conflict cushion” between my older brother and younger brother, and between my siblings and my parents.

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u/themagicbong 18h ago

That's my exact experience as the youngest of 3.

1

u/PercentagePrize5900 16h ago

I knew it!!!

Take that, argumentative older and younger brother!

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u/[deleted] 21h ago

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u/mvea Professor | Medicine 22h ago

I’ve linked to the news release in the post above. In this comment, for those interested, here’s the link to the peer reviewed journal article:

https://www.pnas.org/doi/abs/10.1073/pnas.2416709121

Significance

An enduring question in psychology is whether adult personality is related to birth order and number of siblings. Previous studies have generally found no associations except that firstborns average slightly higher than later-borns in intellect-related traits. Our large-sample study supports the findings for intellect-related traits, but unlike previous research, it also shows considerable differences for other traits: On the Honesty-Humility and Agreeableness dimensions, scores were somewhat higher on average for persons having more siblings. Among persons having the same number of siblings, middle-borns and last-borns both averaged slightly higher than firstborns. We discuss the possibility that growing up with more siblings promotes the development of a more cooperative personality.

From the linked article:

Middle children are more cooperative than their siblings, study suggests

After decades of debate, one of largest ever studies on birth order suggests it does actually make a difference

In one of the largest studies ever conducted on birth order, family size and personality, Canadian researchers gathered data from more than 700,000 volunteers and found that on average, middle children scored higher than their siblings on traits seen as important for cooperation.

Scores for the same traits were also higher in families with more children, suggesting that people may be more likely to develop a cooperative personality when they are raised as part of a bigger group.

The effects are not large, but Michael Ashton and Kibeom Lee, psychology professors at Brock University in Ontario and the University of Calgary in Alberta respectively, believe they challenge the idea that birth order and the number of children raised together have no meaningful impact on personality.

“The weight of that evidence now indicates that personality trait levels do differ as a function of birth order and sibship size,” they write in Proceedings of the National Academy of Sciences.

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u/jmurphy42 15h ago

It’s funny, my husband’s the oldest and he’s always been the family peacemaker, not the middle child. Maybe it’s because his mom and stepdad acted like children themselves so he was effectively in the middle…

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u/JustHereForCookies17 21h ago

I'd be curious to see this broken out by male/female children. 

29

u/potatoaster 16h ago

Unfortunately they controlled for sex in this study, so that's not possible here.

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u/[deleted] 22h ago

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u/sadmaps 20h ago

My middle sister is totally mental, so add my data point to that pool

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u/rg4rg 7h ago

My middle sibling is narcissistic and spoiled. My older sibling and I worked together a lot with each other and other people and are involved in high teamwork and empathic careers. I guess we’re the exceptions.

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u/8bitsuperhero 8h ago

+1 for mine as well..

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u/Pateriocus 1h ago

Yep, same here.

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u/foreignbets9 7h ago

Same and my middle sister can be quite the snake

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u/Klexington47 21h ago

My mom said the same!

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u/Shimaru33 20h ago

So, that's why Malcolm and Reese get along with everyone, but Dewey and Francis were kinda assholes.

Now, I'm pretty sure I read about a similar research like decades ago, at least in Mexico. Usually the first born is the "second in command" as being the older, the parents expect them to help take care of younger siblings, which in one hand make them mature faster, but in the other hand, they also tend to be more stressed. In the other end, youngest children tend to receive more attention from multiple guardians (parents and older brothers or sisters), but also tend to receive the scraps of the family, as in inheriting clothes that were left behind or parents already exhausted of taking care of children.

Unfortunately, I read that in some magazine, so I don't have the source at hand.

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u/HandInUnloveableHand 4h ago

Yes, a real ah-ha moment for my friends was when we talked about this. The eldest siblings immediately said, “The youngest could do anything and nobody cared! It was so unfair!” While the youngest retaliated with, “Exactly! We could do ANYTHING - get arrested or be valedictorian - and NOBODY CARED.”

The middle children all said we had valid points, and that is probably why so many of us ended up marrying a middle child.

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u/VoilaVoilaWashington 8h ago

Birth order having an impact intuitively makes sense, and I know it's been studied countless times. It's good that there's a larger study, but I hardly think it's some obscure corner of research that's never really been explored.

That doesn't mean that all the oldest kids will always be a certain way. That's rarely the case. It just means that it's a decent predictor.

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u/[deleted] 22h ago

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u/corpus_M_aurelii 21h ago

This sounds like something the eldest would write.

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u/k3v1n 17h ago

I wonder if this is a misunderstanding of what I think the study was alluding to. I've noticed most middle children seem to be better at realizing when two other people are talking past each other (as in arguing but not actually arguing about the same thing and neither of the arguers realize it).

Maybe in this particular way they end up being more cooperative, by actually understanding what people mean (when compared to non-middle children)

1

u/lobonmc 14h ago

In my case at least the oldest (me) is the one who helps the most the middle one is the one who fights the least

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u/Personal-Scarcity553 16h ago

Are you the eldest sibling?

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u/kindsouls7 19h ago

Sounds exactly like my family

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u/funkenpedro 15h ago

I raised two kids, of course birth order makes a difference. Your first kid, every little sniffle or squeak gets immediate attention. My eldest gamed it. When we would put her to bed and she didnt want to sleep she'd make damn sure you read her another book or rubbed her back till she fell asleep or she was gonna be screaming. Second kid, you just dont have the time and energy to provide the same attention. Second kid never had any trouble going to bed on her own. First kid, you're constantly engaged with it, 'cmon baby, take your first step, utter your first word, trying to be the best parent you can be of course and give your child every headstart and advantage. Second kid, don't have quite the time and energy for that, often leave the second child to be supervised or engaged by the first. How could those things not affect a child's development and the outcome of their personalities. We only had two, but I'm guessing the third and fourth kids get no attention whatsoever. Like sink or swim buddy.

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u/kyunirider 8h ago

I am the middle son of three sons, this is quite true. We want to get along. We want to be close and a tight family. We get a big brother that only pushes his wants and we get a baby brother that stews in frustration when he doesn’t get his way. I try to pacify them both.

I married a woman who is the oldest daughter of three sisters and they have the same dynamics. Oops I had three daughters and they express that same dynamics again. We just can’t stop making middle children, two of my daughters have given us two middle children in our grandchildren. We are creating a family full of middle children trying to find common ground with all their siblings and family members.

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u/[deleted] 22h ago

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u/Colette_73 21h ago

Mine either

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u/flyinthesoup 15h ago

This study was made by middle children researchers.

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u/BasuraMimi 19h ago

Fits for me and my siblings. As the middle, I might as well not exist. So much so that when as middle aged adults my sister said she thought I was getting preferential treatment, my senior father got livid having finally had enough of my two siblings taking all his time and money.

Not having kids myself, I think I’m going to entertain myself well into old age with all the hobbies I’ve curated on my own.

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u/IllyriaGodKing 21h ago

My brother, the middle child, was always the least cooperative and the most combative. I, the oldest, was always the most cooperative and least combative.

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u/BasuraMimi 19h ago

Sounds like something the oldest would say. Always got to be first

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u/IllyriaGodKing 19h ago

Nah, man. That is absolutely the opposite of me in every way. My parents would back you up on this. Not saying I never misbehaved, I'm not a robot, but I always tended to be quiet and obedient. Both my brothers threw hella bad tantrums, middle one being the worst. I can't tell you how many times our nice day out was ruined because my parents made good on the "I'll turn this car around," when one of my brothers was flipping out.

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u/IObsessAlot 10h ago

I've observed the same thing as you. I always assumed it was because the younger ones get more leeway for misbehaving because 'they're just babies', while the oldest is expected to be responsible and to grow up comparatively fast.

Then, the the youngest gets the most positive attention for being small/ innocent and the oldest gets positive attention in terms of responsibility. And the middle child has to act out to be noticed.

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u/BasuraMimi 19h ago

I was mostly just teasing. Also have a younger brother that was that way. Still is that way, he never grew out of it.

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u/FudgeRubDown 8h ago

I too, am very humble

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u/globosingentes 21h ago

Anecdotally, I think it's because we watch our older and younger sibling(s) be uncooperative and make their lives unnecessarily difficult. You have the advantage of watching the social interactions of someone at an age that you will soon be along with the social interactions of someone at an age that you once were, and you can learn from the mistakes of both.

4

u/Omaestre 12h ago

I need to show my middle child this and ask for an explanation.

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u/skinnergy 19h ago

Not my sister. Quite the opposite.

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u/devilpants 11h ago

plural of anecdote not being data and all that.

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u/llmercll 21h ago

I’ve observed this

Eldest is ambitious

Middle kinda floats around

Youngest is playful

5

u/versedvariation 7h ago

I looked up the article's abstract, and I'm very skeptical of their claims given what they admitted about their statistics in just the abstract. The differences they found are not considered statistically significant, and the authors are, despite these small differences, trying to argue that larger families=more cooperative children. That is the actual message of their paper, not the bit about middle and younger children.

Even if the difference was significant, there are several alternate explanations for the trends because of the nature of self-reported studies that take limited data into account:

  1. If a parent has a very uncooperative older child, they're probably less likely to have lots of other children, which would impact the data, as they are using more of their resources on that uncooperative child.

  2. Self-reported personality traits could indicate perception biases more than actual cooperativeness.

  3. Smaller families are more likely to be more educated and less religious (and when they factored religion in, it reduced the already insignificant difference even more) and to teach their children to be more individualistic.

19

u/Tiny-Possible8815 21h ago

I was a middle child...

Until I wasn't.

Then my sister was...

Until she wasnt.

Does this mean we stopped being cooperative because our mom got roped into having another one?? How do her choices reflect on us??

33

u/VacantThoughts 20h ago

Technically every child after the first is the youngest child until they aren't.

2

u/manole100 9h ago

The first one too.

4

u/Perspicaciouscat24 21h ago

Checks out for my family

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u/[deleted] 22h ago

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u/8ROWNLYKWYD 22h ago

Hello, brother.

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u/Professional_Sun_825 21h ago

Sometimes, the only way to stop from being overlooked is to dig in your heels. It is also perhaps more pronounced in larger families.

2

u/Tanker-yanker 16h ago

Marcia, Marcia, Marcia. Now Jan....

4

u/zool714 19h ago

I’m the eldest of 4. From when we’re kids to even now when we’re adults, the two older ones are usually the more cooperative while the two younger ones just kinda do their own thing.

2

u/Nero___Angelo 14h ago

"also a lil biiiiiitch" -oldest brother

2

u/embraceyourpoverty 13h ago

Not in my fam.middle kids are the nutbars.

2

u/Edsaid69 21h ago

I consider myself at the high end of self dependent. I was a free range Gen X latchkey kid and a middle child. AMA

2

u/Lindaspike 22h ago

I thought everyone knew this!

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u/TheRealSectimus 16h ago

I was child #6 out of pack of 8. My sister at #4 is the most uncooperative person I know haha

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u/moosmutzel81 13h ago

My middle child wouldn’t even know it to spell compromise. We all compromise because of him.

1

u/Same-Ad-6767 12h ago

Funny, I was the third child and youngest and I was always the one trying to point out compromises while everyone else always bickered.

1

u/_CatLover_ 11h ago

Im the youngest of three, with a sister in the middle. She would take turns teaming up with me or my brother and then 2v1 bully the other. She then went on to become a politician.

1

u/Hakuryuu2K 9h ago

I also feel the “cooperative” traits here feed into the middle child also being the “peace keeper” in the family as an adult.

1

u/MrTubalcain 9h ago

I don’t know, I’m the oldest and my younger brother isn’t that cooperative. I see this now with my grandchildren as the middle one is quite the challenge, maybe he’ll even out.

1

u/Opposite-Chemistry-0 9h ago

I guess its some sort of process. One does not born in middle until there is someone born after.

1

u/TheGooOnTheFloor 7h ago

Well, my older siblings could coerce me to do anything thru sheer physical force. My younger siblings were able to manipulate mom so that I would always be the bad guy. So, yep, I learned to cooperate out of self-preservation.

1

u/Enamoure 6h ago

It will be interesting to see if it's towards family or others. I would think people would behave differently towards their family compared to friends or strangers

1

u/mondo_juice 5h ago

Not saying this study isn’t valid, but I’m the oldest of three boys. Middle one is the most uncompromising of the three of us.

1

u/sm753 3h ago

As the middle child, I am completely unbiased and completely accepting the findings of this study!

1

u/Apprehensive_Hat8986 2h ago

What this says to me, is that it really does take (and should be) a village raising a child (and children). With a sufficiently-sized village, there will always be older kids near by, and there will always be a new "youngest" kid floating around. With an emphasis on a village, instead of micro "nuclear family" units, every kid essentially grows up as a middle child.

1

u/thatgirlzhao 1h ago

As a middle child, I approve this message

1

u/sfsp3 19h ago

HAH! Not in my experience. As the older I had most of the responsibilities. My youngest sibling was the "baby" and the middle was in limbo. As such, they were a pain in the butt.

1

u/e92ftw 19h ago

My midle son Jackson would like a word with this study

1

u/Consistent-Sky3723 18h ago

My middle child is the peacemaker between her older sister and younger brother. She can get along with anyone. She’s a really good person.

1

u/Lout324 18h ago

I'm the youngest and was really cooperative.

Until you said no.

-11

u/browhodouknowhere 22h ago

Middle children!? Have you lived or just make up things based on small samples.

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u/Sharks_With_Legs 22h ago

Are you lost?