goofy guy with white sweater

I’ve questioned my introvert status for the last year. I’ve done a lot of research on attachment styles and their influence on our behavior and emotions lately. It was starting to look like my need for space and solitude was more a result of my early relationships with my parents and my later relationships with partners. A month ago, a friend even told me he didn’t think I was an introvert, just a creative type who needed time for deep concentration and work.

Change is the only certain thing

They say nothing is set in stone. It is possible to change your mind or feel completely different about something with time. I used to hate tomatoes, mustard and onions when I was a kid. My dad had to pull up and wait at McDonald’s drive-thru every time to get my special “cheese and ketchup only” hamburger. Now I eat everything on a burger.

But I write about introversion and have advocated for introverts for years! This is not hamburger toppings we’re talking about here. This is my temperament and a trait I have in common with my tribe of readers. I can’t all of a sudden drop my main focus, can I? Glenn Beck did it, but I usually think he and I are different.

Let’s get science in here

I decided to do more research regarding the innate-ness of introversion and high sensitivity. I needed to remember what made me think my quiet introspective nature was something I was born with, not something I adopted.

I turned to the work of developmental psychologist Jerome Kagan. I found the information on Dr. Kagan in the introvert Bible, Susan Cain’s book, “Quiet: The Power of Introverts in a World That Can’t Stop Talking”. Kagan did a long-term study on children starting when they were four months old and ending in their adolescents. Kagan and his staff hypothesized that they could predict which babies would be introverts and which would be extroverts.

In 1989 when the babies were four months old, Kagan and his fellow scientists exposed them to many different stimuli, ranging from recorded voices to popping balloons to alcohol on Q-tips. The babies’ reactions were then recorded. Some babies (20%) reacted immediately and gregariously. They waved their arms and legs and cried loudly. Others (40%) remained calm and only moved their arms and legs occasionally. The remaining 40% fell in between the high-reactors (flailing limbs and crying) and the low-reactors (steady nature, minimal reaction). Kagan predicted the highly reactive babies would become the introverted adolescents and the lower reacting babies would be the extroverts. Flash forward eleven years. Many of the kids dubbed high-reactors were indeed more careful and serious eleven year olds. The low reactive babies were more laid back and confident.

Our nervous systems are different

When the babies participated in the initial experiment and subsequent check-ins at age two, four, seven and eleven, the scientists did more than just observe the children’ reactions to novel stimuli. They also monitored their heart-rate, blood pressure, finger temperature and other elements of their nervous systems. They measured those properties because they are indicators of responses from the amygdala in the brain. The amygdala takes in information from our senses and then tells the nervous system and rest of the brain how to react. If necessary, it sets the fight or flight response in motion. It is the first alert to danger. Children with highly reactive amygdala will do what they can to minimize its reaction in the emotional controlling limbic system (part of the brain where the amygdala resides). They vigilantly search for environmental threats so they can head them off before they occur. They carefully decide whether to join new groups or explore new places, and if they do, they enter each new situation slowly.

Other studies based on identical twins conclude that temperament is on average about 40-50% heritable, meaning our introverted or extroverted nature is partially due to our genetics. How much genetics are responsible varies because the 40-50% heritability is an average.

Kagan even went so far as to say he saw a correlation between blue eyes, allergies and hay fever and high reactivity (ultimately introverted behavior). This correlation is not 100% accepted by other scientists, but Kagan saw a correlation.

Temperament or personality?

Psychologists say there is a difference between temperament and personality. Temperament is a series of behavioral and emotional traits we have at birth. Personality evolves after cultural influence and experiences are added to temperament.

I’ll just dip my toe in the pool

My mother always said I was a colicky baby. I cried a lot. I was fussy. I bet I startled easily (I still do). I never liked summer camp and to this day, I enter a pool or lake very slowly. Cannonballing was never my style. I also have blue eyes and hay fever — just to add to evidence of my predisposition toward sensitivity. So my genetic makeup is probably partially responsible for my introverted nature.woman reading on the beach

The rest of my behaviors and traits can most likely be attributed to the nurturing I received (or didn’t receive) and the environments I encountered over my 47 years. Those traits could be called my personality. Those traits exhibit both introverted and extroverted qualities. For instance, I love to spend my days reading, researching and writing but I also love being part of a loving and engaging social circle. I spend a lot of time thinking about problem resolution, but most of those have to do with making relationships run smoothly. I love reflecting but I also love loving outwardly.

As a child, I learned to figure out my own worries. I didn’t always have opportunities to have my parents help with them. Also as a child, I learned from my father how to be curious about the world and meet new people and explore new places. When it came to emotional issues, I discerned it was safer and/or better to work on things myself, but physical engagement with the outer world was encouraged, although somewhat inconsistently as my mom was fearful of change and novelty.

No wonder I am confused about my temperament/personality status. I guess I could sidestep the questioning and just call myself an ambivert, but that seems like a copout.


When I’m surrounded by secure relationships and get time to go deeply introspective, I am full. I am balanced. I am both introvert and extrovert, but mostly I am content.

Ever wonder if you are a true introvert? Did genetics or culture play more of a role in your personality development?