Research into non-cognitive aspects of human development is all the rage, and this study marries it with our fascination with birth order. It examines how birth order impacts non-cognitive skills, personality traits, and career paths. Analysts use a trove of longitudinal data to address these questions in Sweden, starting with population registry data that include every person born in that country since 1932, specifically data on their birth year, biological or adoptive parents, and biological or adoptive siblings. These data are combined with military enlistment data (until 2010, all Swedish men had to enlist), which include information on non-cognitive as well as cognitive abilities gleaned from a battery of physical, psychological, and intellectual evaluations. They also have data on employment and occupation from 1996 to 2009 for individuals between the ages of 16 and 74 in the labor market and they employ data from the Occupational Information Network (ONET) to generate measures of personality traits (such as conscientiousness, emotional stability, and extraversion) based on their importance to particular jobs. Finally, they include data from a survey of children at age 13 to examine how parental behavior affects kids’ study habits. The final sample includes children whose mothers were born between 1917 and 1964 and who come from families with at least two children but not more than five. Because the military data are limited to males, most of the analysis focuses on men; in total, they observe roughly 560,000 boys from over 260,000 families.
Trust me: these analyses are complicated and must control for a host of variables. Yet the main analysis depends on the simple notion that each child receives a random half of each parent’s genes, which makes parent and child share, on average, half their genes. So it follows, analysts say, that “genetic makeup is not expected to differ systematically between siblings in general or by birth order in particular” and the “effect of birth order can thus be identified by simply comparing personalities of siblings within the same family”—which is what they do.
There are three key findings. First, non-cognitive abilities decline with birth order such that earlier-born men are more outgoing, emotionally stable, persistent, willing to assume responsibility, and able to take initiative than are later-born men. (Those were all of the non-cognitive abilities they were able to measure in the military enlistment data.) Specifically, after controlling for cognitive ability, they find that a move from first born to third born results in 0.11 standard deviations decline in non-cognitive ability.
Second, birth order also tends to impact one’s occupation such that first borns are likelier to be managers. (“Management” here ranges from top-level managers to middle- and lower-level managers, though first borns are also likelier than third borns to be “top managers.”) Earlier borns are also more likely to be in occupations that require leadership ability, social ability, and other personality traits like agreeableness and openness. On the other hand, later borns are more likely to be self-employed which tends to be associated with “risk-loving individuals”.
Finally, adolescent behaviors also vary by birth order. First-born teens are more likely to read books, spend more time on homework, and spend less time watching TV. “Parental investments” decline by birth order in that parents report spending less time discussing school work with later born children. Whether this could explain the fact that certain non-cognitive abilities decline with birth order is an open question.
Unfortunately, this is not a paper about education policy nor does this study have apparent implications for those of us who play in that sandbox. As for parents, the implications are not entirely clear. Should they be encouraging their older sons to teach their younger brothers to be more outgoing and responsible? Or encouraging their younger sons to tell their older siblings to lighten up and take a risk? In the end, we tend to be intrigued by birth order research, if for no other reason than to prove what we’ve known all along: I’m smart as a whip but that brother of mine is a nincompoop.
SOURCE: Sandra E. Black et al., “Born to lead? The effect of birth order on non-cognitive abilities,” Institute of Labor Economics (February 2017).
