A new study indicates that first-born children perform better in school and also suggests why. It's not that they are smarter or have higher self-esteem, but that their parents are tougher on them. "People shouldn't feel limited because they are the second or third child," V. Joseph Host of Duke University, tells Yahoo Shine. "Yes, there are birth order patterns to what we accomplish, but these accomplishments are influenced by many different factors, including how we are raised by our parents." Host co-authored the paper with Juan Patano of Washington University.

The authors, who are both economists, looked at data from the National Longitudinal Survey of Youth, which surveyed more than 12,000 participants. The study controlled gender, divorce, family size, and other factors that might have influenced the outcomes. They found that parents of earlier-born children were harder on them when they brought home poor grades than they were with later-born children. Parents were also more lax with their rules for their younger kids when it came to television watching, video games, and other activities that might diminish time dedicated to homework. The study found that the oldest child in a family of four is significantly more likely to "face daily homework monitoring relative to the last born in that family." As a result, oldest children were more likely to be at the top of their classes and the youngest more likely to be at the bottom. What's also interesting is that the survey found that parents took a tougher approach because they were trying to establish their reputation as a disciplinarian. Once they felt their tough-love style had been established with the first child, they had the tendency to slack off.

 Susan Whitbourne, a professor of psychology at the University of Massachusetts, says she appreciates the study's approach because it's focusing on the role of the parent rather than something intrinsic to a child. "There is so much that's written on birth order that seems very deterministic," she tells Yahoo Shine. "There is the tendency for parents to assume that the oldest is going to be better in school, so they put that expectation on them."

The fascination with birth order and its effect on personality and success goes back more than 100 years, when Austrian psychologist Alfred Adler, a contemporary of Sigmund Freud, first theorized that birth order has an inherent role in shaping personality and classified characteristics of first-, second-, and last-born children as well as only children and twins. To simplify, he characterized oldest children as attention seekers who were confused about their place after being usurped by their siblings. Middle children were competitive and in their adult lives needed to feel superior because they had successfully won their parents' attention and also had authority over their younger siblings. As for youngest children, he described them as being overprotected and prone to feeling inferior.

Since Adler's era, there have been more than 1,000 scholarly articles and many books published on the topic. The result of such intense interest is that today, the idea of birth-order-influenced traits has become codified – almost like one's zodiac sign. At the same time, because people believe so strongly in the significance of birth order, they impose stereotypes on their children, which become self-fulfilling. The eldest is pushed to be a high achiever, the youngest is babied, and so on.

A 2012 review looked at 200 studies on the topic and found that certain themes did emerge in defining the characteristics of people depending on when they were born. According to their tabulation of the data:

First-born children are often highly motivated, Type A personalities who are vulnerable to stress. They are the most conformist and influenced by authority.

Middle children are sociable and least prone to "acting out." They can also exhibit feelings of being an outsider.

Youngest children show the highest degree of sociability and empathy. They are also the most rebellious.