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Comment by vinceguidry | Hacker News Reader

I have a theory that introversion and extraversion don't really exist as personality traits, and that we build up preferences out of existing culture about how much social interaction we want in our daily lives.

If the culture changes, then so will our preferences.

I can easily imagine a world in which I'm gregarious and fun all the time. Making that world happen on the other hand...

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Extraversion/Introversion is one of the big five personality traits and is ~50% heritable:

https://en.wikipedia.org/wiki/Big_Five_personality_traits#He...

That's not to say introversion/extraversion wouldn't manifest differently in different contexts, but the trait does exist (as much as any personality trait does) and appears to have a large genetic component to it.

Isn't "~50% heritable" a different way of stating that the results are indistinguishable from a coin flip? That doesn't sound too hereditary.

No, because it's not a binary choice. There are degrees to which people are open to new experiences or extraverted.

No:

https://en.wikipedia.org/wiki/Heritability

I'd rather interpret it as "50% are fixed (nature) and the other 50% are a coin flip (nurture).

No? Lets say we intro-/extroversion is either heritable (with prob .5) or random(with prob .5). If both of your parents are introverted you have a 50% chance of inheriting the introversion of your parents or a 50% chance at a coinflip, which gives us 75% for introversion and 25% for extraversion.

I took it to mean a covariance of 0.5.

Heritable doesn't necessarily imply genetic. Culture is heritable. Traits can propagate through generations memetically.

"Heritable" definitely means genetic when used in a technical rather than a casual sense, though. Studies control for environment by looking at, for example, identical twins adopted by different families.

Heritability refers to trait variation due to genetic variation within a population.

This is different than the amount genetics actually contributes to a trait.

While you are controlling for environmental factors in heritability studies you are still referring to a specific population. It can be the case that two identical genotypes across two different populations show two different phenotypes.

Having seen how much more sociable the Spanish are compared to the English I'm inclined to agree there is a significant cultural component here. This could be just genetic, but I believe it isn't. A very quick search suggests this is something that academia is considering and has not answered definitively.

Almost certainly purely cultural - look at the huge difference in reputations between how friendly places like Glasgow and Edinburgh are even though they are actually ~75km apart.

My experience has been that people sort themselves into different cities according to their preferences, so there could very well be a genetic component as well.

Having seen how much more sociable the Spanish are compared to the English

I can atest that there are many Spanish introverts. In a very open society you must make an extra effort to fit, but that doesn't change such a traits. My father used to push me very hard to go out and meet people. Annoying at the time, but I'm happy he did.

I'd recommend searching for "Introversion and extroversion brain differences" and similar topics in your favorite search engine. There's evidence that there are physical differences in the brain.

Hopefully somebody with a background in medicine or neuroscience can provide a more comprehensive answer.

And if someone has neuroscience background, maybe they can tell us if that difference is present from birth or if these changes to the brain are environmental based on our social experiences.

I think we are incredibly adaptable and applying a label to ourselves can easily be self-fulfilling. New environment, new you.

I don't believe that, I'm a Skeptic.

I consider myself a skeptic in the sense that I won't believe that any part of my personality is _permanent_ unless proven irrefutably.

In Susan Cain's book about introversion "The Quiet Revolution", she speculated that introversion could become a cultural norm, pointing towards Asian nations as an example.

> I can easily imagine a world in which I'm gregarious and fun all the time

Must be an overactive imagination.

Think "8 year old boy in the 1800s." Castles, dragons, kings, jousting. My mind just doesn't know how to quit.

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