Theories of birth order — hypotheses that character traits are based on where an individual falls within the lineup of siblings — have been around at least since Alfred Adler first proposed his ideas back in 1908. Now, two economists conclude that first children do better in school when compared to later-born siblings because their parents feel the need to establish a 'tough' reputation so that younger children appropriately fall into line. In the end, the oldest child benefits most from a stricter parenting style.
“In particular, earlier born siblings are more likely to be subject to rules about TV watching and to face more intense parental monitoring regarding homework,” the authors wrote in their study. “While further research is needed… we believe that results indicate that parental reputation dynamics may explain part of the observed birth order effects in school performance.”
After examining the literature on birth order effects, the authors apply certain economic models and theories to their analysis of families. They drew their data from the National Longitudinal Survey of Youth, 1979, which included questions about the parent-child relationship asked of both mothers and children. While conducting their analysis, the authors controlled for family structure — such as divorce — theorizing that when children suffer from instability, it affects the younger siblings more than their older brothers and sisters.
First, the team of researchers analyzed the mothers’ answers to the question asked about each of their children: “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?” They discovered mothers were more likely to say their oldest child is at the top of the class and less likely to say the same about younger children. The authors argued that 'parental subjective belief' about a child’s performance matters most, even though the self-reports could be validated against school transcripts. The researchers also analyzed the mothers' tendency to discipline children and found that “earlier-born siblings face a more regulated home environment” with more rules about TV watching and video game playing. Specifically, they discovered the mothers suggested they would be more likely to closely supervise a child who brought home a worse-than-expected report card when the child was 'earlier-born.'
For these reasons, the authors concluded that parents are concerned about their reputation when rearing their first child, and go easier on later-born children after they have established a tough-love reputation.
Other Effects of Birth Order
Two other studies come to what some may find to be surprising conclusions about the effects of birth order.
For one study conducted in the United Kingdom, the researchers compare the birth order of patients who suffer from either posttraumatic stress disorder (PTSD) or adjustment disorder (AD) with population norms. Participants in the study included 83 PTSD patients and 104 AD patients from a psychiatric trauma clinic. After establishing family history, number of siblings, and birth order, the researchers compared the birth order data from the patient group against birth order data from the Office for National Statistics for the same years. They discovered that, when compared to the general population in England and Wales, psychiatric patients with PTSD were more likely to be from a large family, specifically a fifth or later child, and less likely to be the eldest child. Contrarily, no differences existed for birth order between AD patients and the general population.
In another study, a single researcher from East Carolina University decided to test popular culture notions of juvenile delinquency. “While images of the middle child acting out for attention or the rebellious youngest child readily spring to mind, little research has attempted to explain why,” the researcher wrote. Using new methods that allow for greater examination of family differences, the researcher found that, contrary to popular belief, the relationship between birth order and delinquency is spurious. Specifically, birth order differences are “largely products of the analytic methods used in previous tests of the relationship.”
Despite his findings, to many, one of the most convincing theories of birth order is the one proposed by Frank J. Sulloway in Born to Rebel. In this 1996 book, Sulloway takes a Darwinian approach to competition among siblings and hypothesizes that first-born children identify with parents and authority, and so support the status quo, whereas younger children rebel against it. In this way, he extends the impact of family dynamic to society at large, arguing that throughout history, leaders of revolutions (such as Thomas Jefferson) were younger brothers, while older brothers uphold the conservative values of society.
Of course, the truth of birth order effects may evolve over time with children changing as they grow older. One thing that is important to remember is the pioneer of birth order theories, Alfred Adler, was second in a family of six children. His theory of birth order suggested that middle children were most suited to success.
Sources: Hotz VJ, Pantano J. Strategic parenting, birth order and school performance. National Bureau of Economic Research Working Paper. 2013.
Cundiff PR. Ordered delinquency: the "effects" of birth order on delinquency. Personality and Social Psychology Bulletin. 2013.
Green B, Griffiths EC. Birth order and post-traumatic stress disorder. Psychology, Health & Medicine. 2013.