New Study Upends Common Belief About Birth Order and Risk-Taking

The results of a new paper sound a lot like that classic parental refrain, “it doesn’t matter who was born first.” Because when it comes to risk taking, it really doesn’t matter who was born first.

An analysis of three different sets of data — including an original database of 187 “explorers and revolutionaries” (more on that later) — found that neither birth order, nor inter-family personality dynamics influenced whether someone grew up to become a risk-taker. It’s a compelling idea that refutes several previous studies that suggest birth order affects which child has risk-taking personality type. The study was published Monday in The Proceedings of the National Academy of Sciences.

Tomás Lejarraga, Ph.D., a business economics professor at the University of the Balearic Islands in Spain, and the paper’s lead author, tells Inverse it’s perfectly reasonable to wonder if birth order affects personality.

“People’s interest may come from the possibility that they hold strong intuitions about how birth order influences their personality and behavior,” Lejarraga says. “The family is the first and most proximate environment that people encounter during development, so it is reasonable to inquire whether dynamics within the family could play an important role in shaping personality and behavior.”

Lejarraga points to a few papers that have indicated effects of birth order on personalty. One 2010 paper found that younger siblings were riskier baseball players than older siblings. A co-author of that paper, psychologist Frank J. Sulloway, Ph.D., at UC Berkeley, has also developed a model of family dynamics based on the idea that siblings compete for resources. Sulloway suggests that older, dominant siblings tend to protect their privileged status by adhering to more conservative ideas and values, while younger siblings seek new ways to differentiate themselves and gain that covered attention.

As familiar as this model may feel, it didn’t hold up against Lejarraga’s three-pronged analysis. First, he looked at survey data. When checked self-reported data on riskiness from 53,503 members of 11,000 German households who indicated their propensity for risk-taking in activities like driving, financial decisions, sports, or career moves, he found no significant relationship between birth order and risky choices in those activities.

Self-reported data can be flawed, so the team conducted a behavioral experiment on 1,507 individuals. In that experiment, participants performed eight tasks intended to test their propensity for risk-taking. One of those tasks involved a computer game where a participant clicks a digital balloon to “inflate” it with air, and is awarded a financial prize per click while running the risk that the balloon will pop (in which case, they lose the cash). The authors reported no significant results regarding birth order and riskiness in these trials.

About Those “Explorers and Revolutionaries”

Still, Lejarraga and his colleagues weren’t totally convinced. In a final trial, they turned to history to make extra sure they weren’t missing something.

In their final trial, the team compiled a database of 187 explorers and revolutionaries that they believe might demonstrate the effects of birth order and riskiness outside the lab. They compiled this database using Wikipedia’s list of explorers as of October 2018, the Encylopedia Britannica, the book Explorers and Discoverers of the World, and The Encyclopedia of Revolutions and Revolutionaries: From Anarchism to Zhou Enlai.

In that list, Lejarraga and his team still found no correlation between these explorers and revolutionaries and birth order — which adds power to their earlier findings. This list was far from comprehensive, though. For example, the revolutionary list included six women and the explorer list included one — though it did includes names like Adolf Hitler and Leon Trotsky. It’s also missing names like Rosa Parks or Martin Luther King, celebrated risk-takers from American history.

The online version of the list of is an “expanded” list of candidates, but if you download the file, you’ll see the final list of names included in the analysis, based on “eminence criterion” that is described in the paper’s supplementary information and by Lejarraga.

“The sample of explorers and revolutionaries is predominantly male,” he writes. “We constructed the sample using the following eminence criterion: We first identified important published sources of revolutionaries and explorers, and then selected people who had been featured in more than one source.”

Previous trials that included female participants suggest that gender does not impact their final conclusion: birth order doesn’t influence riskiness, Lejarraga says.

A biased record like that list of explorers and revolutionaries from history could impact other studies that employ similar styles of analysis. Importantly, some researchers have already noticed this — for instance there is already a movement to write Wikipedia articles about women who have shaped the world around us to help set the historical record straight.

Third tier of analysis makes a lasting point about who history remembers as a revolutionary or explorer: It may not matter if you are the only, oldest, middle, or youngest child in your family, but, other traits, like gender and race, do leave indelible marks that may continue to influence new insight into human behavior.