If you think your parents let your younger siblings get away with everything, you're probably right. A new study from researchers at Duke University, Johns Hopkins University and the University of Maryland concludes that parents punish older children more harshly -- and they're wise to do so.
The study, "Games Parents and Adolescents Play," finds evidence that parents are more likely to withdraw financial support from older siblings who either drop out of high school -- or in the case of girls, get pregnant -- than their younger brothers and sisters who wind up in the same situations.
Further, the paper presents a mathematical model that supports such unequal treatment of children because more severe discipline of older children deters younger siblings from engaging in the activities for which they know their older siblings were penalized.
The study, published in the April 2008 issue of the Economic Journal, is co-authored by V. Joseph Hotz, an economics professor at Duke; Lingxin Hao, a sociology professor at Johns Hopkins; and Ginger Z. Jin, an assistant economics professor at Maryland. It was supported by a grant from the National Institute for Child Health and Human Development.
"My older sister always complains that she never got away with anything when she was growing up, and we all agree that my youngest sister got away with murder," said Hotz, who was the middle child of five siblings and is now the parent of two grown children. "That's the story of this study."
The researchers began by constructing a model of parent-teenager interactions using the logic and mathematical tools of game theory. The model assumes that parents want their adolescent children to avoid long-term negative consequences that can result from risk-taking behaviors, such as drinking, drug use, sexual activity and dropping out of school. Teenagers, on the other hand, are assumed to value the short-term thrills of risk-taking behavior while also wanting to avoid punishment.
The authors posit in the model that parents need a reputation among their children for following through on threatened punishments. This reputation can change if parents do not punish their children after promising they will.
This reputation factor proved pivotal, as its predictions varied by the birth order of the children. According to the authors' theory, parents have an incentive to punish their first-born child if that child engages in risky behaviors in order to deter such behavior by younger siblings. First-born children, recognizing that their parents are likely to be tougher on their transgressions, are generally deterred from being rebellious. However, this deterrence motive for parents is predicted to wane as their younger children reach adolescence.
"Tender-hearted parents find it harder and harder to engage in ‘tough love' since, as they have fewer young children in the house, they have less incentive to uphold reputations as disciplinarians," said Jin, herself an older sister and a parent of two. "As a result, the theory predicts that last-born and only children, knowing that they can get away with much more than their older brothers and sisters, are, on average, more likely to engage in risky behaviors.
"We became stricter with our son after our daughter was born," Jin added.
To test their model, the researchers looked for evidence of differential treatment of adolescent risk-taking by birth order in survey data from the National Longitudinal Study of Youth (NLSY), provided by the U.S. Bureau of Labor Statistics. They found two measures of adolescent rebellion and two measures of parental punishment. Dropping out of high school and getting pregnant were interpreted as rebellion; not allowing a teenager to live in the family house and not financially supporting a teenager were interpreted as punishment. (Providing financial support was defined as parents paying half or more of a child's living expenses.)
The results of the researchers' analysis of the NLSY data were consistent with their model. The analysis showed that first-born children who dropped out of high school or got pregnant were less likely to be living at home or receiving financial support from parents than younger siblings in the same situations. Moreover, as predicted, younger siblings were more likely to engage in these behaviors, especially dropping out of school, than their older siblings.
"Parents often worry about how forceful of a stand to take in response to their older children's behavior," said Hao, the youngest of three sisters and a mother of one daughter. "Our study finds that some parents are successfully using this strategy of influencing their younger children by stopping their older children's risky behavior."
Despite being the youngest in her family, and therefore less likely to be disciplined, Hao said, "I turned out to be pretty good."