SECOND-BORN BOYS WERE 20 TO 40% LIKELIER TO BE DISCIPLINED
Second-born boys were 20 to 40 percent more likely than first-born boys to be disciplined at school or enter the criminal justice system, researchers found.
The finding came from a National Bureau of Economic Research working paper, “Birth Order and Delinquency: Evidence from Denmark and Florida,” issued in January 2017. Authors Sanni N. Breining, Joseph J. Doyle Jr., David N. Figlio, Krzysztof Karbownik and Jeffrey Roth studied data from Denmark and Florida.
“In families with two or more children, second-born boys are on the order of 20 to 40 percent more likely to be disciplined in school and enter the criminal justice system compared to first-born boys even when we compare siblings,” the authors wrote.
The comparison between brothers is the key. Looking at siblings helps separate birth-order differences from differences between unrelated families. HuffPost Australia also covered the findings.
What the numbers showed
The outcomes included school suspensions, juvenile delinquency and imprisonment. The paper said second-born boys’ involvement with the juvenile justice system was about 40 percent higher than the mean for first-born boys in both Denmark and Florida.
In Denmark, incarceration by age 21 was also 40 percent higher for second-born boys, the paper said.
The gaps showed up in the classroom too. The paper reported lower reading and math scores for second-born boys than their older siblings in Denmark, and lower reading scores in Florida.
ABC13 reported that the school-related measures covered disciplinary actions and truancy, along with juvenile delinquency, adult crime and imprisonment. Birth-order differences among girls were less significant than among boys, the station reported.
The researchers said the results were consistent across Denmark and Florida despite the differences between the two places.
What the researchers said
Doyle did not hide his surprise. “I find the results to be remarkable that the second-born children, compared to their older siblings, are much more likely to end up in prison, much more likely to get suspended in school, enter juvenile delinquency,” he said in an NPR interview published July 4, 2017.
The team used large datasets involving tens of thousands of brothers, NPR reported.
As for why, the paper pointed to parental investment. First-born children received more parental time, measured by time out of the labor force.
Doyle said parental attention and sibling influence may both play a part. He added that the two are hard to separate because they happen at the same time.
He also offered a vivid take on the sibling side of it. “The first-born has role models, who are adults. And the second, later-born children have role models who are slightly irrational 2-year-olds, you know, their older siblings,” ABC13 quoted him as saying.
The findings do not establish that either factor alone causes delinquency. The pattern describes groups of children and does not mean any individual second-born child will become delinquent.
