How Birth Order Affects Social Relationships

by Amanda Ng (’18)

birth order
Fig. 1: Research shows that birth order can affect how we deal with social relationships.

Although much research has been done on birth-order and its affects on relationships, it has mostly focused on theories such as the “middle-child syndrome” and how birth order can affect siblings’ relationships. However, what has not been studied is the idea that a person’s birth order may also affect their prosociality, which is the degree to which a person acts in the interests or benefits of others.

Dr. Catherine Salmon of the University of Redlands in California recently tested this idea. The study involved 220 female undergraduates, 48.6% of which were firstborns, 17.7% were middleborns, and 33.6% were lastborns. The participants completed a series of questionnaires that measured traits such as competitiveness, self-perceived competence, executive function, and emotional control, which indicated their level of prosociality. Better behavioral regulation, higher emotional intelligence, and personality as a general factor were all positively correlated with prosociality. When using a regression model to predict prosociality based on birth order, it was found that later birth order increased prosociality, with the largest difference between the first and second-born child. It is hypothesized that this difference occurs because later born children are less focused on family and parental authority. As a result, the children become more extroverted and in tune with others in order to create connections with individuals outside of the family to set themselves apart from their older siblings.

In the future, research in this field will focus on whether birth intervals or the size of the family affects a child’s sense of prosociality and competence in society.



  1. Salmon et al., The relationship between birth order and prosociality: An evolutionary perspective. Personality and Individual Differences 96, 18-22 (2016). doi:10.1016/j.paid.2016.02.066
  1. Image Retrieved From:

2 thoughts on “How Birth Order Affects Social Relationships

  1. Reblogged this on Awake and Empowered and commented:
    I wonder if more prosociality (working with others, helping others, etc.) for those later in birth order is a result of having to share right from birth. Those born first have a period where sharing isn’t usually necessary unless they are around other children a lot (not usual). Those born later have to share. The later a child is born in the birth order, the more he or she has to share with others.

    I am sharing this in the ‘Communicate’ section of this blog, because it has applicability to communication and relationship building. Whether, as a parent, you may want to keep it in mind when raising your children, or as an adult, you can understand some of the differences between yourself and others.

    I must admit, however, that this was just one study. Also, this study was performed not only on a Western population, but also one fortunate enough to be enrolled in university. I wonder how this may be different if they were to test different cultures and socio-economic groups.

    What are your thoughts? How true is this for you and your siblings (if you have any) and where you fall in your own family’s birth order?


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