Are you an only child — or do you know an only child — who has been called spoiled? Have you heard it said that only children can have trouble sharing, socializing with other children, and accepting compromise? Perhaps you’ve even heard that these children grow up lonely.

Does this so-called “only child syndrome” make you more anxious to give your own child a sibling, pronto?

The truth is, only children sometimes get a bad rap — and this isn’t necessarily warranted, as we’ll soon see. But this reputation gives some people anxiety — and others, stereotyping permission — when it comes to having only one child.

But you might be surprised to learn what researchers and psychologists have to say about only child syndrome. So if you’re wondering whether your child needs a sibling to be a well-rounded person, here’s what to keep in mind.

Related: 9 parenting tips for raising an only child

Most people are familiar with the stereotypes of only children. In fact, you might have used this term to describe someone at some point in your life.

But the “only child syndrome” theory hasn’t always been around. It didn’t come into existence until the late 1800s. This is when child psychologists G. Stanley Hall and E. W. Bohannon used a questionnaire to study and categorize children with a number of different traits. Hall oversaw the study, and both men had ideas based on it published in the early 1900s.

Basically, the conclusion was that children without siblings possessed a long list of negative behavioral traits.

Hall is widely quoted as going so far as to say that being an only child was a “disease in itself.” And Bohannon used survey results (not a very precise science, as we know now) to conclude that only children have a “marked tendency to peculiarities” that are of the “disadvantageous” variety. Both pushed the idea that children would be better off with siblings.

Some studies and research agree with Hall and Bohannon to a certain degree. Yet the consensus is that their findings were unscientific and flawed — essentially making only child syndrome a myth.

In fact, so thoroughly discredited is the original work on the subject that there isn’t much recent — from the last 10 to 20 years — research on the subject.

Related: 5 tips for raising siblings of very different ages

Hall described only children as spoiled, selfish/self-absorbed, maladjusted, bossy, antisocial, and lonely.

Those who buy into the theory believe only children are spoiled because they’re accustomed to getting whatever they want from their parents, including undivided attention. The belief is that they’ll grow into selfish individuals who only think about themselves and their own needs.

Also, lack of interaction with a sibling is believed to cause loneliness and antisocial tendencies.

Some even think these effects carry into adulthood, with only children having difficulty getting along with co-workers, displaying hypersensitivity to criticism as they become older, and having poor social skills.

But while this theory has made its way into popular culture (alongside birth order theories), it’s also largely unfounded. More recent research has shown that being an only child doesn’t necessarily make you different from a peer with siblings. And the lack of a sibling doesn’t doom you to become self-absorbed or antisocial.

Researchers have conducted numerous studies in the last 100 years on only children to determine whether the stereotype is true. Interestingly, results have been mixed. But since the 1970s, it seems that perhaps the majority of only child studies have debunked the existence of a “syndrome.”

Exceptions to this have been closely examined. For example, in Quebec, community samples reported that only children “between the ages of 6 and 11 had a greater risk for mental disorders.” But a few years later, another set of researchers said nope — there’s no difference between children without siblings and children with one sibling when it comes to mental health, at least in children under age 5.

And while it’s true that only children may receive more attention from their parents, this doesn’t always lead to self-centeredness or selfishness. (And let’s be honest — we all know someone who is selfish and has siblings.) If anything, only children may have stronger bonds with their parents.

Respected psychologist Toni Falbo has done a great deal of only child research in the past 40 years and is considered an expert in the subject. She’s still quoted and interviewed extensively about it.

In one of her reviews of the literature, she found that the extra attention a child receives can be a positive. She concluded that only children achieved more than later-borns in larger families. They also had less need for attachments, perhaps because they weren’t deprived of affection.

In another of her reviews, Falbo analyzed 115 studies on only children. These studies examined their achievements, character, intelligence, adjustment, sociability, and parent-child relationship.

Based on her examination of these studies, when compared to families with multiple children, only children surpassed several groups in the areas of character, achievement, and intelligence. The evaluation of these studies also showed that only children had better parent-child relationships.

The million-dollar question: Is Falbo herself an only child? Indeed she is.

Did you know?

There’s a popular belief that in China, where there’s a one-child policy (OCP) in place, a population of “little emperors” is the result — essentially, children who fit the only child syndrome stereotype.

Falbo’s research in the 1990s looked at 1,000 school-aged children in China and found “very few only-child effects.”

A more recent study of hers suggested that only children born before the OCP held less positive self-views than children with siblings held — putting a hole in the theory that only children think more highly of themselves.

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Many psychologists agree that only child syndrome is probably a myth.

One thing to keep in mind is that Hall’s research took place during a time when many people lived in rural areas. And as a result, only children were more isolated, perhaps with only adults to talk to. This isolation likely contributed to character traits like antisocial behavior, poor social skills, and selfishness.

Only children in today’s urban and suburban culture have plenty of opportunity to socialize with other children, practically from birth: at day care, at park and playgrounds, in school, during extracurricular activities and sports — hey, even online.

Psychologists also agree that many different factors help shape a child’s character. And the truth is, some children are naturally shy, timid, introverted, and prefer keeping to themselves. They would be this way regardless of whether they had siblings or not — and that’s OK.

It seems that whenever an only child shows any type of negative behavior, others are quick to attribute this to only child syndrome. Yet, these negative behaviors can also occur among children in large families.

So while psychologists don’t deny that only children may be at risk for some social deficits, these traits don’t occur across the board.

So if you little one seems shy, there’s no need to assume a lack of siblings is the problem — or even that there’s a problem at all. It could just be a natural part of their sweet little personality.

If you’re an only child or if you decide to only have one child, you don’t have to worry about only child syndrome. Many only children are kind, compassionate, and selfless people — who also have strong bonds with their parents.

If you’re concerned about the possibility of your child developing some negative traits, know that you can steer them in the right direction. Encourage interaction with other children at an early age, set limits, and don’t overindulge them.