Time and again, research has shown that first-born children are better at a lot of things than their younger siblings. First-borns do better on IQ tests and are more likely to become president of the United States than their kid brothers or sisters. And, at the other end of the spectrum, first-borns are less likely to do drugs and get pregnant as teenagers.
So it probably won’t surprise anyone that first-borns do better in school than their younger siblings, a finding documented in a recent study I wrote with Juan Pantano, an assistant professor of economics at Washington University in St. Louis.
But why birth order appears to matter so much for school achievement level is much less clear.
Many theories have been posited, ranging from genetics to the stability of family life to the teaching dynamics among siblings. Pantano and I offer a different explanation: It comes down to parents’ reputations for maintaining discipline with their kids. Reputations matter for politicians, teachers, and even used car salesmen. Less obvious, but still important, is a parent’s reputation in their children’s eyes.
The basic idea is this: There are two types of parents—those who in our study we call “unforgiving” in that they will punish poor school performance, regardless of the child’s birth order, and those who are “forgiving,” meaning they don’t like to punish any of their children, regardless of birth. The latter type of parent faces a dilemma. If they don’t punish their oldest child’s poor behavior, all of their children will know that mom and dad are pushovers who don’t punish for poor grades. As a result, all the children of forgiving parents will tend to not work hard in school. To avoid this situation, forgiving parents are strict with their first born, hoping to establish a perception that will influence the behavior of their younger children as well. The younger children, seeing their big brother or sister punished, will be less likely to slack off in school because they can’t be sure that mom and dad aren’t really unforgiving types. Call it “trickle down” discipline—you put the most energy into the first-born, trying to set the tone for all. (As Slate’s Matthew Yglesias put it, it’s a cost/benefit calculation. The cost is the disciplining, which most parents don’t enjoy doling out.)
It is only later that these forgiving parents, who really don’t like to punish any of their children, start slacking off in their parenting. So the outcome of this strategic parenting is that while all children benefit from the first born’s punishments, the impact is greatest on the eldest child.
In our study, Pantano and I looked at data from the children of female respondents who themselves were members in the National Longitudinal Survey of Youth begun in 1979. We focused on families with more than one child. The survey included detailed information on parenting, and we were able to look at parenting rules as reported by mothers and by their children.
While the data does not contain complete information on grades, it does include information on mothers’ perceptions of their children. In some cases we were able to link mothers’ perceptions to actual performance, and found their perceptions to be accurate. For the purposes of this study, however, the mothers' perceptions still gave us a clear picture of birth-order trends.
Mothers were asked, “Is your child one of the best students in class, above the middle, in the middle, below the middle, or near the bottom of the class?” Based on these mothers’ responses, we found a clear association exists between birth-order and school performance. While 34 percent of first-born children were considered “one of the best in the class,” only 27 percent of those who were fourth in the birth order received such recognition. On the other end of the spectrum, only 7.3 percent of first-borns were considered “below the middle or at the bottom of the class,” while mothers classified 11.7 percent of fourth-borns this way.
After establishing the existence of birth-order effects, we then used the data to explore whether differing parental treatment based on birth order affected how children performed at school. We found that first-borns were more likely to face daily homework monitoring than younger siblings. Again, the reputation model is at play here. The eldest children get the most monitoring in the hopes that younger siblings will observe that poor school performance leads to closer monitoring or loss of privileges, and will then have additional incentives to do well in school.
Perhaps the most interesting feature of the data we use is that mothers were asked hypothetical questions about their children’s performance in school and how they would react.
For each of their children, mothers were asked, “If [your child] brought home a report card with grades lower than expected, how likely would you be to keep a closer eye on [his/her] activities?”
This question lets us look directly at parenting strategy. We found that the more younger siblings a child has, the greater the likelihood that parents will closely supervise the oldest child after that child performs lower than expected on a report card. In fact, with each additional younger sibling, the chances of increased supervision rose by 2.2 percentage points.
So what’s the takeaway? While it is often thought that different levels of attainment across birth order are determined at birth and thus unavoidable, our results suggest otherwise. Rather, our findings show that it matters how parents establish discipline and priorities for their children when they are young. Our evidence strongly suggests that the better performance in school by first-borns and the poorer performance by later-borns is the result of differential parenting.
So, the next time you first-borns complain that mom and dad never let you get away with what your younger siblings did, you can be assured that you’re right. And you’re better off because of it.