I can’t tell you how many times I’ve heard someone say something like this after someone has behaved selfishly:
“Oh, I bet they’re an only child.”
It’s actually pretty wild, how pervasive the belief is that people who don’t have any siblings are destined to grow up to be more selfish and even more narcissistic than those who have brothers and sisters.
I’ve been hearing it my entire life. A lot of people I encounter behave as though it’s a given, something that’s incontrovertibly true.
There’s only one problem: It seems to be a myth.
There isn’t a scientific foundation underlying this thing that “everyone knows.”
And instead, a recent study actually contradicts it.
No Increased Incidence of Narcissism Found in Only Children
That study looked at a sample of both only children and individuals with siblings and assessed them for narcissistic admiration and narcissistic rivalry.
The scores on both narcissistic traits were comparable in both only children and folks with siblings — a pattern that held when all confounding factors were controlled for.
The researchers also conducted a study on general attitudes among laypeople about the characteristics of only children and found that the sample predicted that an only child would be higher in both narcissistic traits than a person with siblings would be.
These two studies find that the stereotype of narcissistic only children is widely believed but inaccurate.
Personal Bias Disclosure
Some readers might be wondering whether I am an only child and have therefore chosen to feature these findings for personal reasons. I will go on the record: No, I’m not an only child. I have three siblings.
My spouse is not an only child and has siblings.
I have personally known some only children. I’ve had friends and occasionally dated people who were only children. But those affiliations aren’t driving my decision to write about this research.
The reason I’m featuring this study is because I found the findings interesting and am always amazed to note how many things are accepted by the wider population as “common knowledge” and then don’t pan out to be true upon empirical analysis.
This post is part of an ongoing Poly Land feature called Psyched for the Weekend, in which I geek out with brief takes about some of my favorite psychological studies and concepts. For the entire series, please see this link.
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