Birth Order and Risk-Taking Analyzed by Scientists in Huge Study

Psychologists have long debated whether older siblings are more conservative and conscientious compared with apparently reckless, risk-taking younger children. But, according to researchers, the order in which siblings are born doesn't affect whether a person is tempted to walk on the wild side.

For decades, experts have studied different aspects of the human character—from intelligence to our seeming propensity for hitting traditional markers of success—in an attempt to understand whether being a first-, middle- or last-born child shapes our personality in any significant way. But while there appeared to be patterns in wider populations, experts have struggled to agree on what part, if any, birth order plays on an individual level.

Those who believe in birth order theory say siblings turn out differently because they have to compete for the attention of parents in varied ways: with older siblings protecting their dominance by behaving conservatively, while younger brothers and sisters might learn to fight be noticed, the authors of the new study published in the journal PNAS, of which Psychological and Cognitive Sciences is a subject classification.

They gave the example of Alexander von Humboldt, the intrepid explorer, and his relationship with his "conscientious, prudent, and conservative" older brother Wilhelm as a classic example of the older-younger sibling dichotomy.

In this latest study, researchers investigated risk-taking in siblings. They analyzed birth order in a database of 187 explorers and revolutionaries: two occupations that might attract more daring types, the authors argued. The team also assessed answers from 1,507 participants of the Basel-Berlin Risk Study (who had at least one sibling and completed tests in a laboratory setting) and the German Socio-Economic Panel involving around 11,000 households between 1984 and 2017.

The authors concluded: "The idea that birth order influences personality—and risk-taking in particular—is powerful. We searched for evidence in survey, experimental, and real-world data, analyzing self-reports, incentivized risky decisions, and consequential life choices, but the findings point unanimously in the same direction: There are no birth-order effects on adult risk-taking.

"To understand why Alexander von Humboldt, and not Wilhelm, climbed Mount Chimborazo, we need to look beyond birth order and family dynamics," they said.

Tomás Lejarraga, study co-author and professor at the Universitat de les Illes Balears and adjunct researcher at the Max Planck Institute for Human Development, told Newsweek: "What surprised us was that we looked for the effect as widely as we could, and saw no traces.

"Our results converge with recent studies that show no birth order effects on the Big Five and other personality traits." These include openness to experience, conscientiousness, extraversion, agreeableness, and neuroticism.

Lejarraga argued it is important to understand the nature of risk taking for a number of reasons. "Our findings have implications for the question of succession of a family business. Our results suggest that laterborns will not take more risks than firstborns while managing the family business.

"Also, parents should not attribute laterborns' risky behavior to aspects of their personality—which in principle they could do nothing about—but to the context in which laterborns find themselves. In adulthood, laterborns appear to take the same level of risks as firstborns," he said.

Julia Rohrer, a doctoral candidate at the University of Leipzig who was not involved in the work but co-authored a study showing birth order doesn't affect factors of personality including extroversion and emotional stability, told Newsweek the new study took a "very thorough look at whether or not birth order position is associated with risk-taking and combines multiple data sources."

Referring to the Frank Sulloway's Family Niche theory that first-borns will take on the role of surrogate parents, but later-born children have to take risks in their quest to find an unoccupied niche in the family, Rohrer commented: "One highlight about this study is their analyses of famous explorers and revolutionaries. The original Family Niche Theory was partly motivated by the observation that among historical figures, certain birth order positions were supposedly overrepresented."

However, she said the study was potentially limited because the researchers analyzed samples from Western, Educated, Industrialized, Rich, Democratic (WEIRD) people.

"One of the samples was collected in Germany, another one in Switzerland. Of course, this limitation does also affect most studies that champion birth order effects—but it is always good to keep in mind that broader cultural factors might affect many things, including family dynamics."

"I think one of the main uses of this study is to clarify misconceptions about birth order," she continued. "Many people are still strongly convinced that their birth order position partly determines their life course—more studies that show that there are no clear links between personality and birth order might slowly move the public opinion closer to the scientific evidence."

This article has been updated with comment from Tomás Lejarraga​, and to state the research was published in PNAS, of which Psychological and Cognitive Sciences is a subject classification.

brother sister siblings family stock getty
Researchers have investigated whether the order in which siblings are born can affect their dare-devil tendencies. Getty Images
Birth Order and Risk-Taking Analyzed by Scientists in Huge Study | Tech & Science