Science of Love, Sex, and Babies

Are firstborns likelier to marry firstborns?

Posted in news, Polls and Surveys by jenapincott on February 20, 2010

Opposites attract, but not in marriages or other long-term relationships. As I describe in BLONDES, we value in others what we value in ourselves. So many of us prefer those with similar background, religion, ethnicity, education, values, and so on. Women often prefer potential spouses who look like themselves or family members. We even prefer those whose body language and verbal intonation resembles our own.

The marriage-minded seek the like-minded.

So is it any wonder that researchers have now found evidence that birth order — one of the major forces that influences who we are — also influences our choice in marriage?

In a recent study, Harvard researcher Joshua Hartshone and his colleagues found evidence that people are more likely to form long-term romantic relationships with someone of the same birth order rank. Only children are likelier to marry other onlies, firstborns are likelier to marry firstborns, middleborns are likelier to marry middleborns, and lastborns are likelier to marry lastborns.

The study, based on the responses of over 2,500 visitors to the website, found that the birth-order effects are independent of family size and unlikely to be a product of class or ethnicity. “If spouses correlate on personality,” Hartshone writes, “and personality correlates with birth order, spouses should correlate on birth order.”

Incidentally, the researchers found that best friends also tend to share the same birth order.

My parents are both firstborns. Many of my closest friends are onlies and firstborns who married other onlies and firstborns respectively. Me, I’m a firstborn who married a middleborn.

32 Responses

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  1. Catherine Sherman said, on February 22, 2010 at 10:47 am

    I’m the oldest of six who married the youngest of four. I’ve read studies that suggest that oldest of siblings often pair up with the youngest of siblings, because the oldest is used to being in charge and the youngest is used to manipulating the oldest to get what they want while letting the oldest think they are in charge.

    • Sustainalogic said, on February 23, 2010 at 9:26 am

      Catherine – I agree with you on that and was going to write a research paper on it myself a few years ago!

      I am a first born girl and I tend to clash with other first borns – less so now as when I was younger mind – and I only have a handful of friends who are also first borns. I’ve been out with a range of other birth orders and it worked best with the youngest and the only, so in my personal experience I have to disagree with this study!

    • Julian said, on February 24, 2010 at 12:29 pm

      It’s interesting that you say that my mom is the youngest of 11 while my dad is the oldest of 10.

  2. Halo Reach said, on February 22, 2010 at 10:56 am

    Looks like a “no” so far.

  3. Ann Plattner said, on February 22, 2010 at 11:05 am

    How interesting. I’m an only and I’ve always been drawn to those from big families, usually somewhere in the middle. My best friend is a middle child of five, and my partner is a fraternal twin, the 7th or 8th of 10 children.

    Are you looking at astrology at all? I’m always drawn to similar signs.

  4. thegreathannah said, on February 22, 2010 at 12:40 pm

    I was just recently pondering this myself. It’s perfectly logical. I am a first born and I know I have been decribed as very prominent and not bossy but a leader. I am dating a baby. He was the last born and the two girls above him are older by about ten to fifteen years. Personnaly I think it is a great relationship. We are much alike in what was also mentioned. Religion, the way we walk and talk you know? He has a neice that he is above though so I often wonder if thats sort of a compensation. Eh, I think this was interesting. (:

  5. 1dental said, on February 22, 2010 at 1:21 pm

    Very interesting. I am also curious about what Catherine posted. I am a lastborn married to a middle and have read/heard that people are drawn to those who are like them or complement them. Middles can marry just about anyone, First borns are best with other frists and lasts. Lasts are good with just about everyone but other lasts. I don’t know how scientific it is, but I do agree that the marriage-minded definitely look for like-minded, and I would say are more likely to have a lasting marriage. What are your thoughts on that?

  6. Slamdunk said, on February 22, 2010 at 1:23 pm

    Interesting. Same as you–I am first born who married middle child.

  7. Goncalo Botelho said, on February 22, 2010 at 1:48 pm

    I find that completely relative. I know really loads of people who were attracted and married someone with a different birth order. They live happily active lives and have kids.
    My parents (both around their 50s) for instance, are married and still going strong nowadays doing romantic trips on their own, sometimes they even work together, they solve problems together etc.. My mother was first-born and my father was the very last being born from my grandparents who had 8 children.

  8. Kat Musselwhite said, on February 22, 2010 at 1:54 pm

    I find this really interesting, mainly because I’ve long felt that birth order has a huge impact on the person we become.

    Personally, I’m the baby of the family (slightly spoilt by two older brothers I will admit!!), and my other half is also the youngest, but acts more like the eldest due to circumstance!

    But in the past I’ve been out with eldest, middle and only childs, my current boyfriend is my first youngest, so-to-speak!

    So yes, very interesting 🙂


  9. impassionedplatypi said, on February 22, 2010 at 2:51 pm

    This isn’t anything I’ve ever really paid attention to. I’m the second of 5, though I suppose I could almost be considered the oldest as far as relationships go because my older sister is 12 years older, so she was out of the house by the time any of us were really old enough to pay much attention. My serious relationships have consisted of a youngest, and two oldest. The youngest doesn’t exactly count normally though because he was an only for his parents and had an older half brother.

  10. Kat Musselwhite said, on February 22, 2010 at 3:01 pm

    That’s funny, I was just saying to my other half about how the middle child in my family is partly the eldest, because our older brother is seven years older than him, and nine years older than me. I can never imagine my eldest brother as a child, and most of my childhood memories surround me and my middle brother. The actual eldest was more like a close uncle in a relationship sense!

  11. Lakia said, on February 22, 2010 at 3:48 pm

    I’ve only dated three people throughout my life, but now that I think about it, all of them have been the babies of the family. My first boyfriend had an older brother, but my last two had older sisters… this is strange lol

  12. akbillue said, on February 22, 2010 at 5:21 pm

    so interesting!

  13. timwaagh said, on February 22, 2010 at 6:10 pm

    interesting. now because this is social science, somebody will propably publish a paper about it, probably using multiple regression analysis. Then somebody else will publish a paper which proves the opposite, also using multiple regression analysis (and the same data), bottom line: this will never be science.

  14. Kat Musselwhite said, on February 22, 2010 at 6:31 pm

    Surely it’s Psychology… Not Science?!

  15. dancingrealm said, on February 22, 2010 at 7:08 pm

    very interesting. My husband and I are both first borns. I’ve always heard however, that its better if the birth sequence is not the same in spouses…

  16. Rachel said, on February 22, 2010 at 8:33 pm

    I am a firstborn. My husband is a second born (or last born since there were only 2). But, I have read that since he is the firstborn male he is still considered a firstborn (it would work the same if he was first and his sister was born second, she would still be considered a first born). Also, I think that they say how many years apart the births were contribute to your birth order ranking. So, in our family we would all be considered first born. We have 2 sons and 2 daughters. The first “set” is 8 & 7 years older than the oldest of the 2nd “set”. I think in so many ways it has just as much to do with the way you were raised as it does your attitude about being the oldest or youngest or somewhere in between. This kind of stuff can certainly be fun to read and see if any of it pertains to you though 🙂

  17. pt4themind said, on February 22, 2010 at 9:34 pm

    This is interesting. I dated four people and all of them have been the oldest with younger brothers except for one. Maybe i should find someone who is the baby of the family.

  18. Stacy said, on February 22, 2010 at 11:31 pm

    Rachel ~ I’ve always wondered if the first born boy acted as the first born, even though the actual first born was a girl. Both having traits of first borns. I’ve heard this stuff for years . . . always interesting.

    I have six siblings and I’m the second born of the 7. On the website link above regarding birth order, I’m the quiet middle child . . . sandwiched between the oldest girl and the oldest boy. I married an only child. The descriptions on that website definitely outlined us both . . . we have our moments but we work well together, going on 8 years. My mom and dad, on the other hand, both first borns and going on 41 years. :0)

  19. jrvitalis said, on February 22, 2010 at 11:33 pm

    Fun discussion – thanks! Stop Pinching Your Sister!

  20. Melissa Strader said, on February 23, 2010 at 1:52 am

    Enjoyed the Blog! Thanks

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  21. Blogsss;* « Tweet's Bloggg;* said, on February 23, 2010 at 9:58 am

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  22. addy said, on February 23, 2010 at 10:13 am

    I’m a first born married to am middle – second boy. I feel I’ve learned to be more “yar” (philadelphia story), to let go a little of my role as leader and gatherer. He’s learned to take the lead and enjoy it. Works out better and better every year.

  23. Jerica Winans said, on March 8, 2010 at 12:05 pm

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  24. CockGawker said, on March 12, 2010 at 1:10 pm

    I’m a last born female married to a first born male. In the past I’ve been drawn to and dated first born males.

  25. Rebecca said, on March 19, 2010 at 6:21 am

    Very interesting. Great theory with lots of truth.

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  26. Myrtle Beach Discount Taxi said, on March 30, 2010 at 10:56 pm

    im an only child, dating an only child. and my mother was the youngest of 4 and married my dad youngest of 3.

  27. Susan said, on May 8, 2010 at 8:32 am

    First borns can marry first borns..It works well

  28. B A said, on September 17, 2010 at 2:17 am

    What is very interesting in this day and age is that just as likely to meet up with a first or last born. That is, with people having only 2 kids usually, it’s sort of a 50% chance.

  29. Jessica said, on April 28, 2011 at 8:28 pm

    I am a first born married to a first born, my brother is the middle child dating a oldest, and my sister is the youngest dating an oldest, my husband is the oldest of 3, I am the oldest of 3 and we have 3 children

  30. Nina Evans said, on May 11, 2011 at 3:13 am

    My best friend and I have completely different upbringings and I am an only child whereas he is the youngest of three. We have much in common; but, because of the common traits we share we fight – like brother and sister. He was, also, my husband…twice.

    The man I currently see is the middle child and we have everything in common except our looks. He is my opposite. He is someone I want to marry and grow old with. He calms me; he makes me think and he challenges me to new experiences – he is, also, a best friend.

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