Introverts are finally getting our time in the sun. There are more websites, books, and communities for introverts than ever before—enough that young introverts can grow up understanding themselves, instead of feeling “wrong” like I did as a kid. But there’s no shortage of people who still don’t get it. Anytime I mention I’m an introvert, someone asks something like, “Why can’t you just learn to be social like everyone else?”
That viewpoint is backwards, but it does raise a good question. Do people “learn” to be introverts as they grow up, or are we introverts from birth? In other words, what makes you an introvert—your genes, your upbringing, or some mix of both?
The Science of Young Introverts
To answer this question I turned to Dr. Marti Olsen Laney’s book The Hidden Gifts of the Introverted Child: Helping Your Child Thrive in an Extroverted World. Laney gives a detailed rundown of what we know about young introverts, including the specific factors that cause them to be introverted in the first place.
Like most questions of nature versus nurture, Laney tells us that the answer is a little bit of both:
“Yes, children are born with an innate temperament. And yes, parents are vitally important to how that temperament is nurtured.”
But she emphasizes that introverts are (mostly) born that way. Specifically:
- The degree to which you are introverted or extroverted is influenced by genetics.
- Out of all the personality traits that have been studied, introversion/extroversion is one of the most strongly hereditary ones.
- Nonetheless, a lot of environmental factors—like how you’re raised—influence it too.
These aren’t guesses on Laney’s part. She pulls together some of the best neurological research on introverts to show exactly how genetic it is—and why some factors can defy your genetic “programming” to change your disposition.
The Genetic Basis for Introversion
Laney says the basis of being an introvert lies in our biochemistry. Human brains have a mix of over 60 neurotransmitters, chemicals that determine exactly how the brain works. While those chemicals are largely the same from person to person, we each have slight differences—our own “recipe.” Your recipe is determined by your genes, and is with you from birth. It also determines many personality traits, such as your tendency toward introversion or extroversion.
This correlation is so strong that Laney says children show their introversion/extroversion tendency from the moment they’re born.
The most important of these neurotransmitters is dopamine, which rewards you for pursuing external rewards. Introverts’ brains are far less driven by dopamine. We don’t get the buzz from it that extroverts do, so we don’t seek as much external stimulation.
Our dopamine sensitivity is an example of our neurotransmitters in action—and it’s determined by our DNA.
How Genetic ‘Set Points’ Make You Flexible
Introversion isn’t totally genetic. It gets influenced by your environment at a young age, and our genes allow a certain amount of flexibility in response. This happens through “set points,” which are the upper and lower limits of how much extroversion your brain can handle.
Laney compares these set points to setting a temperature range on a thermostat. You might program your thermostat to keep your house between 68 degrees and 74 degrees Fahrenheit. Within that range you’re comfortable and no climate control is needed. But if it gets too cold or too warm, the heater or AC kicks on and you have to spend energy to get back to the comfort zone.
The brain works the same way. As an introvert you might want more social time one day and less another day, and as long as you’re within your “set points” you’re okay. But if the stimulation takes you beyond your upper set point—maybe by going to a big birthday party—we all know how drained you’re going to feel.
That means two introverts with the same genetic disposition could come across quite differently. One might stay closer to the high-stimulus end of their comfort range, while another stays cautiously at the low end. These behaviors are largely learned through experience. If a child gets enough positive experiences with social time, they might enjoy pushing the top of their range, even though they’re an introvert. A child who has negative experiences could develop more reclusive, quieter ways.
A Portrait of Three Kids
To see how this works, let’s look at three hypothetical children. All three are introverts, but they’re not all the same:
- Jen and Amanda are identical twins. They have the same DNA and very similar brains at birth. Both show signs of being introverted, but their “set points” are quite wide. They could act more social or more introverted on any given day.
- Matthew is also introverted from a young age. However, his brain has fairly narrow set points, much narrower than Jen and Amanda’s.
Despite being all introverts, the children turn out very differently.
Jen has some early positive experiences that reward social activity. She’s older than Amanda by several hours, and people always ask if she’s going to be the “leader” of the two. When she does something bold or showy, adults laugh and cheer. This positive encouragement makes it fun to stay toward the top end of her set point range and be a social introvert.
Amanda has the opposite experience. When she does something showy, adults say she’s copying her sister. She doesn’t find it rewarding to come out of her shell as much. By the time she’s old enough for preschool, she isn’t as excited about making friends as Jen. Other kids stare at the twins, and she takes this attention as negative. She’s happier when she stays near her lower set point. She’s considered the shy one.
Matthew has a different upbringing. He’s an only child and his parents give him a lot of positive attention. They can see his introversion early on, and instead of being critical, they try to gently encourage him in social situations. They take him to the playground, join a play group with other families, and put him in a private preschool that encourages creativity.
But Matthew stays introverted. Even though his group experiences are positive, he has a very low set point for external stimulus. He comes back from play dates cranky or sleepy. He’s well adjusted socially, but he prefers inner, imaginative activities to people time.
So Are You Born an Introvert, or Not?
These children are imaginary, but they correspond to patterns that many of us have lived in real life. Your genes give you a “range” of introversion. A wide range could be heavily influenced by how you were brought up, but a narrow range means upbringing won’t change you as much. This is why Laney says the answer to the nature vs. nurture question is, “Yes… and yes.” Your genes make the choice, but they can make you flexible, too.
What’s clear is that your preference for introversion or extroversion gets fixed early on. As much as your experiences might shape you, Laney says most children stay true to whichever preference they showed in the first four months of life.
I can clearly see experiences in my own life that helped give me my strong introvert tendencies, such as being a misfit at school. I also wonder if I might have a “narrow” range of set points, more like Matthew than Jen and Amanda, as I can happily spend weeks at a time with no social contact.
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