The 30-year-old founder and CEO of Detail.com is the youngest of three siblings. He credits his family for giving him the freedom to be creative and take risks. “I had complete freedom to leave my part-time job, drop out of college and start a new life on another continent.”
The idea that younger children are more adventurous is just one of several theories that explain how family positions affect us as adults. An even more popular idea, and almost a fact, is that the firstborn has many years of experience as a senior and is therefore more likely to become a leader.
Scientific evidence in this area is weak. But this does not mean that the presence of siblings (or lack thereof) does not have any effect on us. Recent evidence suggests that the age gap between siblings, the ratio of boys to girls, and the quality of relationships between children are important.
Arguing about who rides in the front seat of a car or who stays up late is actually important. Fighting and negotiating siblings can really help arm yourself with useful personal skills.
Born to lead?
There are many dramatic articles on the Internet that claim that firstborns are more likely to become leaders. This idea is confirmed in individual cases: European leaders Angela Merkel and Emmanuel Macron, for example, are first-born, as are recent US presidents Bill Clinton, George W. Bush and Barack Obama (or were raised as such – Obama had older half-siblings with whom he didn’t live). In the business world, Sheryl Sandberg, Marissa Mayer, Jeff Bezos, Elon Musk, Richard Branson were the first to be born, just to name a few of the famous CEOs.
Yet several studies have debunked the notion that birth order does shape our personality. In 2015, two major studies found no significant association between birth order and personality traits. In one case, Rodica Damian and Brent Roberts of the University of Illinois assessed the personality traits, IQs, and birth order of nearly 400 American high school students. On the other hand, Julia Rohrer of the University of Leipzig and her colleagues assessed the IQ, personality and birth order data of almost 20 people in the UK, US and Germany. In both studies, several small correlations were found, but they were insignificant in terms of their practical significance.
Another popular idea related to birth order is that younger children are more likely to take risks – but this claim was also debunked when Tomás Lejarraga of the University of the Balearic Islands and colleagues found no significant association between adventurousness and birth order.
Love for brothers and sisters helps
Not having a firstborn or younger effect doesn’t mean your role in the family hierarchy hasn’t shaped you. It may be the special nature of your relationship and your role in the family’s power structure. But then again, as the scientists note, caution is needed – if you find a link between sibling relationships and behavior later in life, there’s a much simpler explanation: personality stability. Someone who cares about their siblings may just be a very caring person, with no real causal effect of kinship.
There is evidence that kinship brotherhood has far-reaching psychological consequences. First of all, siblings can either cause mental health problems or protect against them, depending on the warmth of the relationship. The gender of our siblings may also play a role in our later careers, with one study showing that men with older sisters are less competitive, although it’s important not to exaggerate the practical scale of this effect here.
Another important factor is the age difference between siblings. A recent study in the UK found that younger siblings with a narrower age gap tended to be more outgoing and less neurotic – likely because they had to compete for their parents’ attention on more equal terms and were also more likely to play together and learn from each other.
It should also be remembered that brotherly and sisterly relationships do not exist in a vacuum – brothers and sisters tend to have the best relationships where they grow up in a happy home environment.
The power of one
Emotional resilience, empathy, and social skills are obvious strengths in many professions. Research shows that having a sibling you get along with can be a great training ground. But what if there are no brothers and sisters?
A study that compared the personality traits and behavioral tendencies of people born in China shortly before and after the introduction of the one-child policy found that children in this group tend to be “less trusting, less trustworthy, less risk-averse, less competitive, more pessimistic and less conscientious.”
Another study showed the possible social consequences of this fact – participants who were only children received lower scores for “friendliness” (they were less friendly and trusting). On the positive side, however, the only children in the study performed better on creativity tests, and the scientists attribute this to their parents paying more attention to them.