Born to connect

My project is testing different kids birth orders and and see if the birth order matches there 4 closest friends birth orders
Lauren Au
Grade 6


If I survey at least 50 children, I will find that most of their closest friends will be of the same birth order as them.  For example, the first born children’s friends will also be the oldest in their respective families.  In the same way, the youngest children in their families will most likely have a friend group of last-borns. 



  • Popular belief is that birth order does affect personality, but when you look deeper at the results of studies, you find that the evidence does not support this belief
  • A common statistic that is used when speaking about this topic is that 21/23 NASA astronauts that were chosen for space missions were first-borns. Some assume that this statistic means that first-borns are more ambitious and intelligent
  • Studies since 1980’s show mostly that birth order does affect personality
  • Hartshorn states that Family Size is the biggest influence upon personality.
  • Family Size affects the percentage of being first-born (you have 50% of being a first-born in a 2-child family, but only a 20% chance in a 5-child family).  It also affects the amount of money, time, and attention each child receives. 
  • Family Size can also be affected by cultural background, level of education, and/or wealth
  • Of approximately 65,000 articles listed by Google, most do not take Family Size into consideration
  • Dr. Kevin Leman, in The Birth Order Book: Why You Are the Way You Are (1967) states that sibling personality differences lies in birth order and how parents treat their child because of it. This theory is supported by Meri Wallace, a child/family therapist, in Birth Order Blues (1999)
  • Parents of First Borns are extremely attentive, stringent with rules and overly neurotic about details, causing them to be perfectionists, controlling, structured, cautious, conscientious, reliable and always striving to please
  • Parents of Middle Borns are less strict with rules and less attentive, causing them to be people pleasers, somewhat rebellious, thrive on friendships, have huge social circles, and are peacemakers
  • Parents of Last Borns have become increasingly more relaxed towards parenting, causing the Last Borns to be fun-loving, uncomplicated, manipulative, outgoing, attention seekers (with natural charm), and self-centred
  • Parents of Only Children direct all of their support and attention to the child, therefore, they are mature, perfectionists, conscientious, diligent, and leaders
  • Popular belief is that birth order shapes personality and defines stereotypes (Eg. First-borns = intellectual, mature, responsible, conformists. Later-borns = risk takers, creative rebels)
  • Popular book, Born to Rebel by Frank J. Sulloway (1996), confirmed this belief and stereotypes
  • IQ of adults could be affected by amount of mental stimulation they were given as children
  • But since 1996, there has been a growing amount of evidence to disprove Sulloway’s theories and these studies use more data and show a relationship between birth order        personalities-but in adults
  • 2015 study assessed 20,000 people in Germany, US and UK and found that birth order did not alter “Big 5 Personality Traits” (Conscientiousness, Openness, Extroversion, Agreeableness, and Neuroticism)
  • Rodica Damien, a US social-physiologist studied 375,000 high-school students in 2015 and confirmed that birth order does not influence the “Big 5”. But she and other scientists have found that birth order does slightly influence intelligence with First-Borns having an average of 1-2 higher IQ points
  • Null Effect” = studies that do not show significant effects are often not published 
  • Sulloway quoted a 1968 study that shows that Later-Borns more likely to play dangerous sports. He also quoted a 2010 survey that showed that Later-Borns in Major League Baseball are 10x more likely to attempt to steal bases
  • Study conclusions may also confuse birth order and age. Some personality traits are developed later, so a subject may have a type of characteristic not because of birth order, but because of influences gained from age
  • Damien does state that birth order affects grown-up personalities but looks at how culture and education are also influences
    • Eg. Family Size (affected by wealth and education-levels) could affect statistic that Harvard’s 2021 class is 40% firstborn, 32% youngest born and 14% middle siblings



My Controlled Variables are the questions we are asking the Subjects and that they are all under the age of 18.

My Manipulated Variables are that we are asking different children of differing ages. 

My Responding Variables are the responses of the children and whether their birth order matches the birth order of their closest friends.



  1. Gather as many participants as possible* goal to have at least 50
  2. Ask them these questions (What is your birth-order? and What is the birth-order of your 4 closest friends?)
  3. Collect data  from at least 50 children
  4. Record data in one place
  5.  Analyze data, create graphs based on the results


  • ​​​​​​​Laptop
  • Used social media to collect participants



My conclusion shows some pattern but overall had no real conclusive findings linking birth-order and your choice of friends.  It does however show that the oldest/only have a higher percentage match but it didn't really affect the results.


As suggested by the Background Research, parents likely give a different amount and type of attention to each of their children. This creates common personality traits among oldest/only children, which then affects whom they choose as friends  

This is probably because most families have 2 or less children. Where there are less than 3 children, there are no middle children at all

There may be no obvious patterns for Youngest children due to family size. So they may all be “Youngest”, but they could be the youngest among 2, 3 or more siblings



Over the past 100 years, many studies have tried to prove that there are stereotypical personalities due to birth order. (Eg. Youngest are risk takers, Oldest are more responsible, etc.) This experiment shows that birth order doesn’t necessarily affect personality or choice of friends. So we can use the results to teach kids that they can be the type of people they want to be and choose friends who may be like or unlike them.


Sources Of Error

Ways I could have improved or expanded my project: 

  • Consider that some people have disabilities
  • Consider their gender
  • Consider how to classify twins
  • Consider that more than one person in a friend circle was surveyed, resulting in overlapping results
  • Consider size of families

Sources of Error

  • The possibility that participants may not have been truthful
  • With all studies involving human participants, you must consider sample size. My project involved 77 participants, however, many more participants would have given me more reliable data.


Guarino, Ben. “Birth Order May Not Shape Personality after All.” The Washington Post, WP Company, 12 June 2019,


Hartshorne, Joshua K. “How Birth Order Affects Your Personality.” Scientific American, Scientific American, 1 Jan. 2010,


Voo, Jocelyn. “Birth Order Traits: Your Guide to Sibling Personality Differences.” Parents, updated July 30, 2020.



2 people I would like to thank are my teachers Mr.Baillie and Ms.Summerscales because they helped me alot during my research and gave me tips for my project

Also I would like to thank my mom so much for helping me with everything this year but asspecially science fair 

So thank you to those people for helping me get to this point