Does birth order matter?

Published on Psychology Today

Three years ago when my son was born, my life changed forever. The first few months were the most difficult of my life, but the ones that followed were among the best. Every day I watch as he developed and became a more delightful person. It was difficult to imagine loving anyone more, even a second child. Which is why when I found out I was pregnant again, I couldn’t possibly fathom what it would be like to have a second son—one that I would obviously love as much as the first.

Besides being worried about loving the second one as much as the first, I was also worried about how much time I would have for a second child; having one is hard, but splitting time between two (and a husband and full time career) sounded exponentially harder. Would I be able to give the second child as much attention as I’ve given the first? Would my first son still get enough time with me, even as I’m nursing the second? How would the second time around be different?

First, I quickly saw that physically having the second child was significantly easier than having the first. When I went into labor, I knew exactly what was happening, I knew when to go to the hospital, and I knew what to do when I got there. I already knew how to nurse, how to burp a newborn, how to change a diaper, and how to swaddle. I knew that leaving my newborn alone for a few minutes in the crib was perfectly safe, and that I could easily take a shower or make myself some lunch without having to worry about every second that I wasn’t watching closely over my new baby. I knew that crying wouldn’t hurt him, and I knew that every bump in the road would eventually pass.

All in all, I am way more relaxed for the second child than I was for the first. But then again, I’m also more tired, busier, and have less total time to devote to #2, because I have a 3-year-old who is perfectly capable of telling me when he wants my attention, and has a full repertoire of strategies up his sleeve that he can use in order to get it.

It certainly feels like there are large differences between the way I can be a parent to the first child versus the second, even though I’m still me, I’m raising them in the same house, with the same environment, in the same family. Watching these differences unfold before my eyes has made me wonder about the effects of being the born first versus being born later. Are there real effects of birth order?

Although it’s hard for me to believe that these differences in my own behavior won’t have a real effect on my children, research on birth order is surprisingly controversial. One of the most consistent findings documented by several researchers is that children born first tend to do better in school throughout childhood, and some have even reported that they have a higher IQ than children born later (see Hotz & Pantano, 2015, for a review). In contrast, younger siblings tend to be more rebellious, agreeable (Paulhus, Trapnell, & Chen, 1999), and open to new experiences (Healey & Ellis, 2007).

Although some researchers have suggested that differences in school performance and IQ might be because babies conceived later are born to older moms whose biology is more apt to producing problems during pregnancy, the most widely accepted explanation is that parents have less one-on-one attention to give children who are born later and fewer financial resources; thus, these children get less attention academically and socially. Another view is that as the result of getting more attention from parents, first born children are motivated to fulfill parents’ expectations and therefore become more responsible. Conversely, as a result of wanting to a find a place of their own in the family, children born later are less conforming to what their parents want, and therefore more rebellious and open to new experiences (Solloway, 2001).

These theories are controversial, as are the realness of birth order effects themselves. Indeed, while several studies report effects of birth order on both academic achievement and personality, other studies report no such effects (e.g., Bleske-Rechek & Kelley, 2014). What’s most likely is that if birth order effects do exist, they’re not huge and likely vary widely based on several factors, such as the spacing between kids, total number of children in the family, as well as cultural, and socioeconomic differences.

But besides birth order effects based on differences in parenting, the mere occurrence of having siblings present in the household could also affect a child’s development. For example, having a sibling has been shown to be related to the development of prosocial emotions like sympathy that might help children develop more advanced social skills (Harper, Padilla-Walker, & Jensen, 2016). Sibling support has also been shown to be a buffer against problems with depression and self-esteem in adulthood (Milevsy, 2005). In contrast, only children (who grow up without siblings around) have been shown to be more creative than children with siblings, but less agreeable, and recent work suggests that such differences might even be reflected in the development of the brain (Yang, Hou, Wei, Wang, Li, & Qiu, 2017).

From my own observations thus far, I can’t see how birth order will no effect on my children. My first son experienced 3 full years of the undivided attention of a more stressed mother who was experiencing parenthood for the very first time. He has always had guidance for every new milestone, and careful attention has been paid to every one of his needs (at least until the second one was born). My second son has a mother with less overall attention to allocate to his development and he will likely have to do more on his own, but in a much more relaxed environment. He also has an older brother—another child in the house—that will motivate his development in very different ways. So I fully believe that having a sibling will inevitably change the lives of both of my sons, hopefully in ways that are mostly positive. I grew up with a younger brother, and I can say with confidence that I wouldn’t be the person I am without him in my life, in the best ways possible. I can only hope that the same will be true for my sons.

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Bleske-Rechek, A., & Kelley, J. A. (2014). Birth order and personality: A within-family test using independent self-reports from both firstborn and laterborn siblings. Personality and Individual Differences, 56, 15-18.

Healey, M. D., & Ellis, B. J. (2007). Birth order, conscientiousness, and openness to experience: Tests of the family-niche model of personality using a within-family methodology. Evolution and Human Behavior, 28, 55-59.

Harper, J. M., Padilla‐Walker, L. M., & Jensen, A. C. (2016). Do siblings matter independent of both parents and friends? Sympathy as a mediator between sibling relationship quality and adolescent outcomes. Journal of Research on Adolescence, 26, 101-114.

Hotz, V. J., & Pantano, J. (2015). Strategic parenting, birth order, and school performance. Journal of Population Economics, 28, 911-936.

Milevsky, A. (2005). Compensatory patterns of sibling support in emerging adulthood: Variations in loneliness, self-esteem, depression and life satisfaction. Journal of Social and Personal Relationships, 22, 743-755.

Paulhus, D. L., Trapnell, P. D., & Chen, D. (1999). Birth order effects on personality and achievement within families. Psychological Science, 10, 482-488.

Sulloway, F. J. (2001). Birth order, sibling competition, and human behavior. In H. R. Holcomb, III (Ed.), Conceptual challenges in evolutionary psychology: Innovation research strategies. Boston: Kluwer.

Yang, J., Hou, X., Wei, D., Wang, K., Li, Y., & Qiu, J. (2017). Only-child and non-only-child exhibit differences in creativity and agreeableness: evidence from behavioral and anatomical structural studies. Brain imaging and behavior, 11, 493-502.