I am an only child. Saying this sometimes feels like a confession – not least when people respond with a well-meaning “oh, you don’t seem like it!”. Now, as the mother of a preschooler, I see my daughter navigating the same assumptions. “Does she have older siblings?” one teacher asked recently. “She plays so well with the other kids!”
If it seems like I am bragging about my (or my daughter’s) behaviour, you will have to excuse me: I am, after all, an only child.
Advertisement
For over a century, we have been seen as odd, at best; antisocial, neurotic and narcissistic, at worst. “Being an only child is a disease in itself,” declared 19th-century child psychologist Granville Stanley Hall.
Whether there are actually any differences between the personalities and well-being of singleton children and those with siblings remains a contentious question – one given fresh impetus by the growing trend of one-and-done parenting.
Single-child families have become more common since the 1970s in high-income countries, including the US and UK, whether “by constraint or by choice”, says Éva Beaujouan, a demographer at the University of Vienna, Austria. In Europe, nearly half of all households with children have just one child.
Despite their growing popularity, one-child families continue to encounter a long-held view that this arrangement is somehow harmful. Fortunately, delving into contemporary research can offer a degree of clarity – and it hints that being an only child can come with surprising outcomes. The findings may offer some reassurance for one-and-done parents and those still debating how many children to have.
What is only child syndrome?
The negative stereotype of only children is often said to date back to Hall, the first president of the American Psychological Association in 1892. But it was his protégé, E. W. Bohannon, who gave Hall’s beliefs the gloss of science by conducting one of the first studies on the subject. In it, Bohannon he considered to be “peculiar and exceptional”, categorising them by traits as varied (and dubious) as “stout”, “obedient” and “whining”. Being an only child, which applied to just 46 of the children – and which, he claimed, was marked by characteristics like “selfishness” – received a category of its own.
It is likely, though, that only children were viewed as the odd ones out far earlier than this. That is because, statistically, they would have been. While it is easy to forget now, women arguably have been able to control their fertility in a dependable way only since the 1960s, with the . Our hunter-gatherer ancestors averaged around four or five live births in a lifetime, while the settled lifestyles and more predictable nutrition of the agricultural revolution led families to have even more children, more quickly.
The upshot was that, for almost all of human history, only children often signified some kind of family issue, like poor parental health or malnutrition, says at the University of Texas at Austin, a leading researcher of only children.
The relative unlikelihood of being an only child in the past has probably led to the assumptions of our weirdness. After all, it is human nature to ascribe one notable characteristic to another notable characteristic, says psychologist at Witten/Herdecke University in Germany. “People often look for the attribute that distinguishes you from the others, and use that to explain how you behave,” he says. If an only child doesn’t share, onlookers may be quick to say it is because they are an only child. But if a child with siblings doesn’t share, few would attribute it to their having siblings.
This has caused the entrenchment of some particularly damning stereotypes. A 2019 study by Dufner that of 1810 adults who did and didn’t have siblings is a case in point. The researchers also polled a further 556 people about the type of person they thought likely to be narcissistic.
Contrary to the ingrained belief, adults without siblings were no more likely to show narcissistic tendencies than those who did have siblings. Unfortunately, the study also showed that respondents had bought into the stereotype. They were far more likely to say that only children were narcissistic – especially if they had siblings themselves.
“If you’re not an only child, then you tend to think that these only children are all spoiled narcissists,” says Dufner. “But it seems not to be true.”
Such bias hasn’t just moulded cultural perceptions. It has shaped decades of research – a wrong turn made worse by other methodological issues, like small sample sizes and a failure to control for other factors that could explain any differences. To get closer to the truth, we need to look to better-designed studies of only children and see what they say. Doing so reveals a very different picture, even if it is sometimes still blurry. “Both educationally and developmentally, [only children] tend to either be better off, or show no difference at all,” says , a demographer and population geographer at the University of St Andrews, UK.
Only child traits
One popular misconception that has been debunked by rigorous study is the oft-claimed view that lone offspring end up with poorer well-being than their counterparts. Research that their responses with those from when they were in high school in 1960, for example, found that only children were either equally happy and satisfied with their lives – or more so – than those with siblings.
More recent research has come to similar findings. In May, a meta-analysis of 113 studies that included almost 240,000 participants in China led by Yu Tao Xiang at the University of Macau, China, concluded that only children were , including depression, anxiety and OCD, than those with siblings.
Not having siblings means you also tend to do a little better on and , presumably because parents have more time and resources to with just one child. In the long term, though, these educational differences .
The lonely only-child trope is crumbling too. In 2022, Shengjie Lin, then at the University of Texas at Austin, and his colleagues looked at more than 1200 young adults in China and found that than those with siblings.
“The evidence is not there,” says Falbo. “Some of the research for late childhood and early adolescence suggests that only children do spend more time on their own. But they’re not distressed by this.”
While the lack of correlation between “only” and “lonely” might surprise those with siblings, it tracks with what we now know about loneliness. It is a complex phenomenon, and more related to the quality, not number, of relationships someone has – not only for , but and .
That applies as much to your siblings, should you have them, as to other relationships. One 2009 review noted that while having a good sibling relationship can have benefits, a poor one was linked to everything from worse academic outcomes to aggression. More surprisingly, it reported links between positive sibling relationships and later problem behaviour, if one of the siblings engaged in “deviant behaviour” like substance use or school delinquency.
Having a large number of siblings can also be problematic. Last year, Douglas Downey and Rui Cao at the Ohio State University published work on some 18,000 teenagers across the US and China that concluded having more siblings was . And this year, a study by Keenan and her colleagues discovered that having three or more siblings came with a higher risk of both cancer and worse overall health at midlife. “The record is pretty clear,” says Falbo.
It is a similar story when it comes to the idea of the selfish only child. The reverse may actually be true. In one of her , Falbo used a prisoner’s dilemma game, which permits the use of cooperative or competitive behaviour, to see how children interacted. Rather than being more competitive than kids with siblings, only children were the most likely to respond to a cooperative move in kind. This suggests, she wrote, that “growing up with siblings enhances interpersonal competitiveness rather than cooperativeness”.
Still, she doesn’t dismiss the idea that children without siblings may be a little different in terms of sociability – if, by this, we mean being more comfortable on their own.
That could even play into one long-term finding of a potential difference that does seem to hold water: only children are slightly than those with siblings. In one sample examined to reach that conclusion, each sibling someone had reduced their divorce risk by about 3 per cent. The researchers suggest that this stems from a difference in interpersonal skills. Falbo isn’t so sure. She thinks only children may simply be more comfortable striking out on their own.
Meanwhile, even researchers who have argued that having brothers and sisters provides an advantage in social skills say the scale of the difference is often overblown.
One of the most-cited pieces of work that supports the social skills divide is a 2004 look at more than 20,000 5 and 6-year-olds in kindergarten in the US. As rated by their teachers, only children were found to have more trouble like interrupting or fighting. Even five years later, according to a follow-up study in 2015, .
However, any differences were minor. When you drill down into various aspects of social skills, the largest gap concerned interpersonal skills: in kindergarten, the average rating for this was 3.04 out of 4 for only children versus 3.15 out of 4 for kids with siblings. By fifth grade, it narrowed to 3.12 for only children and 3.18 for siblings. “The difference is not meaningful,” says , a sociologist at William Paterson University in New Jersey and a co-author of the 2015 follow-up study. More confusingly still, some research has found the opposite: that only children are .
And of course social skills lend themselves to forming close friendships. Is this easier if you have had to get along with siblings? Yucel co-authored a study in 2015 on this, finding that, in general, kids with siblings were than only children. However, they were a little more likely to if their sibling relationships were high quality.
It could be that these children had learned social skills from their siblings. Or, wrote Yucel, it could be a chicken-and-egg conundrum: a more sociable child simply has better relationships with both siblings and peers.
Raising an only child
Which brings us to the kind of quandary that can muddy these waters, despite all the research. It is the question of how environmental factors might affect matters. A good example emerges from a 2020 analysis by Keenan and her colleagues of Swedish population data. In it, they found that beyond the age of 50, risk of dying during the study period compared with kids with one or two siblings. Talk about a motivation to have a second child.
But the researchers say that is probably the wrong conclusion to draw. It is likely that certain families stopped at one child for reasons that affected their child’s health unconnected with sibling status. Parents might have had chronic health issues like diabetes or cardiovascular problems, for example, factors that are known to influence a child’s future outcomes and that the researchers couldn’t control for, says Keenan.
The same line of argument may apply to temperament, a personality aspect that remains relatively stable from infancy. Some parents could be stopping at one child because that child has a , suggests Yucel. If so, we would expect groups of only children to look, on average, different from the rest – but not because they lacked siblings, per se. Yet most studies, she says, don’t include children’s temperament.
Meanwhile, a family’s decisions can often buffer any potential impacts of having siblings or not. Take a 2022 , Denmark. It found that 1-year-olds with older siblings , and a lower risk of asthma, than children without older siblings. This isn’t surprising, says Keenan, who also researches the microbiome, as the more children there are, the more bacteria are probably being shared among a family. “That’s not to say that the answer to all of our problems is to have more children,” she says. Spending more time in nature and having a pet can similarly boost the diversity of a child’s microbiome.
Which is a large part of why any meaningful outcomes that specifically stem from being an only child, if they exist, are so hard to pin down. “As much as I love talking about my research and my findings – and don’t get me wrong, I think there’s value in that – we also need to acknowledge our limitations,” says Yucel.
Different families make different choices. A child who grew up in a financially stable, nurturing environment with plenty of play dates may turn out quite differently than if that same child grew up in a household marked by financial stress, interpersonal tensions and long periods of being left alone – with or without siblings.
That is why, researchers say, the question ultimately shouldn’t really be whether it is better to be an only child or have siblings. It should be what is best for your family.
Unfortunately, the prevalence of only-child stereotypes means parents may be making choices about family size based on fears that aren’t rooted in reality – rather than making the best decisions for them. “Every family needs to think about their financial resources, their personal values and where they are at in their lives,” says Yucel.
With all of this in mind, I ask Falbo whether those stereotypes will finally die. She sighs. “I’ve been doing this research for many years, finding either no difference or a slight advantage for only children, and that has not done much at all to improve the stereotype of the only child,” she says. “Scientific evidence is, apparently, not going to change it.”
Amanda Ruggeri is an award‑winning freelance journalist and editor based in Switzerland
