Don’t use birth order as an excuse, you’d be wrong!

I was born the second son and older brother to my sisters, fraternal twins, who are two years younger than I, in a family of four children. Sometimes I wonder if my life would have been different as the oldest, the youngest or even as an only child, which, on occasion, I would have preferred. The latter would have been my preference during this recent school break at home as I just needed to sleep, have some quiet time and get school work done. It is hard to meet any of those needs with my family of 6 people. There is always someone in the bathroom when you want to use it, someone playing the television or talking too loudly, specifically when I am on the verge of thinking of a great blog idea!

My parents have referred to me as the middle child, even though there are four of us, because my younger sisters are twins. In terms of birth order, I am in the middle so I can understand the categorization. I came across the chart below and started thinking about my personality and that of my siblings. While each of us resemble the descriptions for our birth order, any one of us can check off certain characteristics in the other categories as well.  That led me to my hypothesis; Birth order doesn’t drive personality traits since we are all individuals with different likes, needs and desires.


Picture source:

A study, published by the Proceedings of the National Academy of Sciences, or PNAS, used a compilation of data for approximately 20,000 subjects representing people from Germany (10,457), America (5,240), and Great Britain (4,489). Given the size of the sample, the results were considered statistically significant. The analysis assessed the subjects in the same families and between different families. It evaluated the subjects with specific assessment for what are considered the big five personality traits:

  • Openness – being imaginative and willing to try new experiences
  • Conscientiousness – being reliable, organized, methodical and a planner.
  • Extraversion – being energetic, talkative, assertive.
  • Agreeableness – being friendly, kind, sympathetic and compassionate.
  • Neuroticism – emotionally unstable, moody, tense, worrier.

Confounding variables considered in this study included; family size (family size of more than 4 siblings were excluded), age disparity of siblings, socioeconomic status and genetic susceptibility.

This study was conducted to determine if birth order defines the direction a person takes in life. It described and refuted the early studies that originated the birth order theory. Francis Galton conducted a narrow study of first-borns in 1874, concluding parental favoritism drove intellectual superiority.  Alfred Adler defined the birth order theory in the early 1900s, suggesting that personality is influenced by such order. Finally, the Family Niche Theory, produced by Frank Sulloway, in 1996, was reviewed but dismissed because of the limited sampling of only one sibling per family and a subject self-rating model of themselves and their own siblings.

The research conducted for the study was independent, robust and thorough. It reflected consistent, proven results of broad analyses and data. It claims to have achieved a power of 95%, which translates to a mere 5% potential impact on our lives, driven by birth order. I believe that this topic fits the framework of correlation does not imply causation topic that Andrew shared in class.


This credible and statistically significant study determined that, intellect aside, there is no lasting effect on the big five personality traits, because of birth order. I must admit that the data presented was a bit intimidating to dissect, but after reading through it a couple of times, I think it makes logical sense. In my research, I came across this personality test. It is free and claims to be reliable. It might be an interesting test to do with family members over the winter break!


Study: Examining the effects of birth order on personality:

The Big Five Factors:

Personality test:

8 thoughts on “Don’t use birth order as an excuse, you’d be wrong!

  1. Francis Patrick Cotter

    A lot of people have told me that personality is very influenced by birth order. I am the baby of the family, therefore I am deemed have all the qualities associated with the last baby and the wearer of all thing hand-me-down. However, I believe there are so many third variables active in personality development that birth order is limited to shaping only a portion of your personality in a specific setting. However, that is just an anecdotal observation on my part. The data your presented does a good job of disproving the commonly held belief that personality is a serious determinant of a person’s personality.

  2. Lauren Eve Ribeiro

    I think this blog could have been really interesting to read if it was more thorough. This blog caught my eye when I was reading it because of the chart that you included. I am an only child and in the chart it says that we are “confident, conscientious, responsible, perfectionist, center of attention, mature for their age, seek approval, sensitive and leaders”. When reading this I was amazed because I felt like this perfectly described me. However, because your blog was lacking a lot of evidence, i started thinking could these personality traits be due to something else. I looked up my astrological sign, which is a leo, and found that some of the most common traits were “Creative, passionate, generous, warm-hearted, cheerful, humorous, self-centered”. I felt that a lot of the characteristics over lapped, with the common theme that only children and leos were both dominant and confident in what they do. I think your blog could have been a lot more convincing that my traits are due to me being an only child if their was more evidence.

    1. Michael Robert Szawaluk Post author

      Lauren – thanks for the feedback. I would suggest that you read the study by PNAS I included in the blog because it did include a broad range of subjects and a significant amount of evidence. Quite frankly, I don’t believe that astrology as evidence of personality traits would be considered scientific evidence by credible scientists. As a Virgo, I am “always paying attention to smallest details”, so I thought I would share that with you.

  3. Matthew Porr

    I think that the research on this topic is lacking because there are only 2 studies. However 20,000 is a lot of subjects I think they excluded a lot of people. The study mentioned that they excluded results from families with more than 4 children. I think that this research could benefit by changing the structure of the study, getting more specific, and having a more controlled study. They could have possibly focused on a families with only 3 children and compare the personality tests with one another depending on their birth order and see what correlations they find. While I understand that correlation does not equal causation, you never know what you are going to find if the research on this topic continues.

    1. Michael Robert Szawaluk Post author

      Matthew – Thanks for your feedback. I suggest that you take a look at the PNAS study in the blog (see the full text tab on the link for the details). I think you will find that this study has a large number of subjects and compares “within-families” and “between families” of varying sizes. Analyses match families of similar sizes (less than 4 in a family) across three countries.

  4. Claudia Lynn Hatch

    I am not sure how much evidence there really is to back up a claim like this, however I did find it very interesting. I am the oldest of eight children so I totally understand what it is like to live with a ton of people, and to have to share the bathroom. I remember learning about the five traits in AP Psychology, so I found this blog to be intriguing. It took my knowledge further, and I appreciated that. I think you could have organized your thoughts better, but overall you did a good job. This video is a crash course on measuring personality traits and I found it to be very helpful.

  5. David Louis Haselkorn

    I do not think this is an arguable topic. It never occurred to me that the order in which you were born determines your personality traits. This is not something that can truly be tested no matter how thorough of a study they conduct. While I agree that family plays a big role in shaping your personality I do not agree that the order of which you were born makes a difference. There are too many family situations for something of this magnitude to be determined. In this article ( you can read about the science behind what really determines your personality.

  6. Mackenzie French

    I love taking personality tests just to see if I feel like I fit the criteria they conclude. I also have an older brother who is very different from me. Not just because I am a girl and he is a boy, but our personalities, motivations, and likes are very different. Yes we do have some similarities, but I thought your post was interesting way to look at personalities depending on when you were born. I can’t relate to you since I don’t have younger siblings, but I was curious to see what you had to say. This is an article I found which relates to this idea of personalities between siblings, check it out!

Leave a Reply