Birth Order May Not Mean Much

Have you ever heard that the oldest sibling is the smartest, the middle child may tend to be more rebellious and the youngest one is always searching for more attention?  Studies are showing that birth order may not effect one’s intelligence nor their personality. Coming from a family with three children this has been a talked about subject for quite some time, whether it is true or not. While some of the stereotypes hold true for us, others were the opposite. Being the youngest, I can see why we are often thought of as attention grabbers. We always try to keep up with our older siblings and want to establish our place in the family. Middle children are often assumed to be forgotten about and therefore act out more. This was so not the case for my sister, the middle child of the family, she was the angel of the bunch and could normally do no wrong in the eyes of my parents. My brother, the oldest, was the rebellious one but probably the smartest as well. He is now an oral surgeon and doing very well for himself. All of that to say, I was very curious as to if these myths were true.


A study conducted at the University of Illinois asked themselves the same question. They studied 377,000 high school students to find out if birth order had any correlation with intelligence or personality. They sorted through the 377,000 and excluded those who were only children, a twin, triplet, etc. and any who were not a credible source. This left them with 263,712 students to study. They asked their participants several questions about their family life background (i.e. who they live with), demographics and personality. In addition their intelligence in many subjects was tested. As we have learned in class, there are several different outcomes that could appear when looking at a correlational study, if the two do indeed correlate.

  1. The birth order could be causing the intelligence and personality of the student.
  2. The intelligence and personality of the student could be causing the birth order.
  3. A confounding third variable could be responsible for the correlation.
  4. It was all due to chance.

The reverse causation, number two, does not seem possible. The third variables seems probable just as a hypothesis. The study did take into consideration these factors such as the number of siblings in the family, the families socio-economic background, the age and gender of the student and family structure. They collected two sets of data, one controlling these confounding variables and another without them controlled. The results proved to be rather interesting. There really was not any large correlation between birth order and intelligence/personality. With the variables controlled, the correlation was at .02 which is a positive correlation but not anywhere close to 1. It only jumped up a tiny bit with the variables unconcealed.

A smaller version of a similar study was done at University of Wisconsin. They had a much, much smaller sample size and were looking into more how birth order can influence personality, not so much intelligence. They also studied how parents perceived their children based on their birth order. Most parents did not perceive their children any differently but it was common for them to say that if one child was extroverted, the other would be introverted. Their results were similar to the first study in that personality is not caused by birth order but rather by genetics or by the environment they were raised in.

Now that we have strong evidence that birth order does not cause a certain personality type or intelligence level, we don’t have to place ourselves in certain categories based on where we are in the lineup. If your family does follow the stereotypes, it is most likely due to chance as the correlation is so low. So just because you are the youngest child, does not mean that you can’t achieve a 4.0 G.P.A. and just because you are the middle child does not mean you have to be a rebel. We are free to be ourselves!


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8 thoughts on “Birth Order May Not Mean Much

  1. Victor William Gregory

    Hey Monica,
    I found this post very compelling as I am one of four children. I agree that as a society we think of children a certain way based off the order they were born, but i believe it has more to do with the way our parents raised us than anything else. I agree with you and the studies you discussed that birth order has no affect on your intelligence, but i think its possible that birth order could indirectly affect our personalities. Growing up in a house with three older siblings you watch what they do, and you learn from their choices. The more siblings you have the more you learn at a younger age. I think that this could be looked into further however, i’m not sure how far a study such as this would be able to go based of the ones that you discussed in your post.

  2. Rebecca Aronow

    This is a really great topic for a blog post. I’ve always found the effect of birth order on intelligence and personality to be really interesting, especially while analyzing myself and my sister. I’m the oldest of two children; my sister is two years younger than me. We’re both intelligent, but contrary to largely held beliefs about birth order, my sister is academically smarter than I am. We haven’t gotten an IQ test but I believe that her IQ would be higher as well. I do, however, feel like I am the more responsible one. But, although I was a role model to my sister, as I’ve grown older my sister has become a role model for me as well. So, your conclusion that birth order does not cause certain personality types or intelligence levels agrees with my experiences. But in researching I found a journal article from the Journal of Instructional Psychology that made me think of this topic in a slightly different way. The abstract of this article states that a student’s role in a group learning setting needs to be chosen based on their role within their family (i.e. their birth order). The abstract argues that children’s personalities and behaviors develop as a result of their place within their families, so teachers should try to maintain a balance between the student’s role in their family and their role in the classroom. This made me think that we can’t conclude based on the studies that you mentioned that birth order has nothing to do with intelligence or personality, because every experience we have in life influences our personalities and how we develop intellectually, and much of those experiences do have to do with our birth order. For example, I feel responsible as the oldest child to set a good example for my sister and am therefore responsible and always looking after others. My parents also treat my sister and myself differently just because I was like their “test-run” child and they felt a bit more relaxed raising their second kid, so my younger sister got away with more and was able to do things at a younger age and therefore matured earlier than I did. So, I don’t think birth order dictates who we turn out to be, but I definitely think it impacts us in many ways that are hard to scientifically measure.

  3. Olivia Frederickson

    I’m from a family of 3 siblings as well so this was a very eye-catching topic. I’m the oldest of 3 sisters and on one side of my family, the oldest of 5 grand-daughters. Naturally, the conversation at big family dinners has been about where I’m going to college, what my grades are like, who are my friends, etc. These correlations that you list certainly pertain to how my family views me, but I also agree this is due to chance. I know for certain my younger sister, the middle child, is smarter than me and one day she will be the focus of discussion at the dinner table. I think people tend to correlate the placement of siblings too much with intelligence or integrity. I really enjoyed reading your blog since you constructed it very cleanly and made it easy to follow focusing directly upon this correlation. How you listed the possible conclusions or theories made it easy to follow and really think about what each study was conducting. Although, I think you should ask more questions that explain one step further the possibilities. You could ask how much does culture play into sibling ranking, or wealth, or even if sex and age are possibly correlated. These are other confounding variables and may also affect the outcome of the conclusion.

  4. Jarrod T Skole

    Great blog Monica! I only have a sister so I do not know much about middle child syndrome or any of those stereotypes, but I do fall into the stereotype that the youngest child is more of the baby than the older child. In my case this is the opposite. I am the youngest but tend to take more of the in charge role whenever my sister and I are left alone. I think that a child is the way they are just based on who they are, rather than then the stereotype they are given. Id also like to talk about the theory that the middle child is the least loved or least remembered. My best friend is one of three and happens to be the youngest. He has two older sisters, but the funny thing is that the middle child is the one who gets all the attention. His father treats Shannon, the middle child, like a queen. So I believe that it doesn’t matter what order you are born in when it comes to getting attention or the way you are.

  5. Mary M. Brown

    Monica, I love the way you crafter this study. I have am older half-brother who doesn’t live at home and a younger brother, so I’ve always been stuck in between the stereotypes of both the oldest and middle child. Personally, I am super type-A and organized, and not at all rebellious, so I’ve never felt that birth order has meant much. But it was so interesting to read about the science behind it! Honestly, I think that the personality of a child has nothing to do with birth order, but could possibly have more to do with gender or the environment in which the child was raised. Here/a> is an article linking different genders with different personality traits. It’s worth the read!

  6. Gulianna E Garry

    Monica, I found this study very interesting. I only have a younger sibling and even though our personalities are very different, I now believe that it has nothing to do with out birth order, but just who we are. I believe you may find the theory of ‘middle child syndrome’ very interesting. After reading your blog, I wonder if middle child syndrome is actually real, since it’s theory is based on the order the children were born. Here is a here looking a little more into it! Enjoy.

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