Born to Rebel: Birth Order and Personality

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Updated on Mar 26, 2014

Grade Level: Middle school; Type: Life Science, Social Science


  • Learn about personality traits and tests
  • Explore birth order effects
  • Explore the relationship between personality traits and birth order effects

Research Questions:

  • On which of the “Big Five” scales were your subjects’ average results similar to Sulloway’s results?
  • On which of these scales did your subjects’ average results differ from Sulloway’s results?
  • What is the nature of the criticism against Sulloway’s interpretation of his results (you will be able to find this information using the links provided below)?

Research by Frank Sulloway (1997) supports a link between birth order and personality characteristics (as assessed using the “Big Five” personality test). Sulloway contends that first borns are more extraverted and conscientious, less open to new ideas and less agreeable than younger siblings. However, many people disagree with his findings. In this study, you will ask students to anonymously complete an on-line Big Five personality test, and also to provide you with information about the number and birth order of children in their family. You will assess the relationship between personality characteristics and birth order in your data, then compare them to Sulloway’s original findings.


  • Access to a computer and printer
  • Graph paper, pencil (preferably colored)
  • Cardboard box or bag
  • Box of envelopes

Experimental Procedure

  1. Recruit as many subjects as possible (try to get 30 people) to take the “Big Five” Personality Test on their own computer or one available at your school or public library. The test is available at here. When you recruit participants, tell them that when they complete the test and hit the "submit" key, they will be presented with their scores for five different personality dimensions. [Note: They will also receive percentiles for each score, but you won’t be using that data in your study so be sure to ask them to provide you with the raw scores.] Tell them to write the following information on a piece of paper 1) each dimension and their associated raw score, as well as 2) the number of children in their family and their placement in the birth order (e.g., “There are four children in my family and I’m the third-born child). Provide them with an envelope and tell them to put their results inside and seal it, then bring it to you at school (or your home if it’s a relative or friend) and place it in a collection box or bag. [Note: You’re providing them with an envelope and having them place it in a box or bag so that you will not know which results below to which person; this is done in order to protect your subjects’ privacy.]
  2. Create a data collection sheet by making 7 vertical columns on the graph paper and label the top of the columns, from left to right, as follows: Birth Order; Number in Family; O; C; E; A: N [The letters in this acronym stand for the different scales on the “Big Five”: Openness to new experience; Conscientiousness; Extraversion; Agreeableness; Neuroticism.]
  3. Record the data for each subject [Note: you can save some time by grouping the data for first borns, second borns, third borns, fourth borns, etc.]
  4. Average the scores for openness for first borns, and continue calculating averages for each personality trait for each of the birth orders.
  5. Create bar graphs of all five traits for each of the birth orders.
  6. Assess your results to see if they are similar to Sulloway’s [e.g., are you finding that your firstborns are more extraverted and conscientious, less open to new ideas and less agreeable than later borns?]
  7. What other interesting patterns do you notice in your results?
  8. Check your results for any only children; are their results more like first borns or later borns?
  9. Discuss your results; what factors might explain personality birth order effects?

Terms/Concepts: Personality; Personality trait; Personality test; “Big Five” Personality Test; Birth Order; Correlation


Dr. LaCerra is an evolutionary neuroscientist, author of âThe Origin of Mindsâ (with co-author, Roger Bingham, Harmony, 2002) and a columnist and contributing editor at âSpirituality & Healthâ Magazine.

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