Extroverts, Introverts and Their Genes | INFJ Forum

Extroverts, Introverts and Their Genes


Captain Obvious
Retired Staff
May 8, 2008
Type me.
Conventional comparisons between identical and fraternal twins indicate that nearly half of individual differences in personality traits have some underlying genetic cause. So people have tended to think of personality traits as largely determined by genes, says evolutionary psychologist Aaron Lukaszewski of the University of California at Santa Barbara.

He felt there was a flaw in this thinking: if personality were rigidly determined, individuals could end up with the "wrong" personality type for their circumstances. Being extrovert, for instance, exposes people to social conflict. Wimpy men are more likely to suffer in such encounters, while hunkier men may benefit from putting good genes on display. To avoid mismatches, Lukaszewski reasoned, evolution must have favoured a more flexible system.

To test this idea, he measured the strength of 85 male and 89 female students and asked them to rate their own attractiveness relative to their peers. Then he gave each a standard personality test to measure how extrovert they were. Sure enough, stronger and more attractive men, and more attractive women, were more extrovert, Lukaszewski reported at a June meeting of the Human Behavior and Evolution Society in Eugene, Oregon.

Independent ratings of attractiveness showed extroverts didn't simply tend to rate themselves more highly. In fact, physical strength and how people rated themselves explained a whopping 30 per cent of the variation in extroversion between the volunteers - a huge effect for something as nebulous as personality. "That's surprisingly high to me," says Robert Plomin of the Institute of Psychiatry in London. "That makes it much more interesting."


I haven't noticed any correlation like this in my personal experience, but in an evolutionary context, it makes sense.
I have noticed a corralation. A weak one, but I have noticed it. Also remember there is a huge difference between actual attractiveness, and perceived attractiveness, I bet that has come into play here. It really does make sense if you think about it. I know I certainly have become a lot more extroverted over the years as I have gotten much more confortable with myself (although I am still an introvert).
I doubt they are measuring the actual amount of introversion and extraversion (as described by Jung and MBTI).

No. of people that tests as extraverts ≠ the number of actual extraverts

I have no doubt that being strong and attractive would make you feel more extraverted, finding out whether that is actually the case or not would involve a lot of self reflection etc.
What has this to do with genes?

It didn't become clear how they measured "physical strength", I hope not by community opinion, but by some objective health tests, but then again this could mean extroverts are more likely to develop their bodies better. Well, extroverts tend to be more active on average, so? About the community-based measure, of course extroverts get higher scores for attractiveness. They also get higher scores on how smart they are viewed to be by peers, which doesn't mean it's objectively true. Same for the World of Warcraft experiments - not surprising at all, actually it would be surprising if people were not affected by the imaginary "value" of the features they sport. This is extrapolation from old placebo experiments like the Jane Elliott experiment. You just have to make people believe they have high importance and value, and they begin to act with more confidence and dominance. If anything, this shows most evaluations of social influence are superficial.

p.s. traditional evolution is dead, it only exists in past tense, since we've figured it out; it would be superstition to keep obeying it in our social affairs.
Honestly, I'm not sure I buy this idea that attractive people are predestined to be more outgoing. I know some rather ordinary people who are quite extroverted and some really gorgeous people who are much harder to get to. I think your E vs. I ratio is shaped partially by genetics, and also by your unique experiences-- an introvert who suddenly has a number of positive social experiences during which they took "extroverted" risks may start developing more extroverted tendencies. On the other hand, an extroverted kid who has a whole lot of social problems at school may ultimately develop into an introvert as a response to these experiences.

Above all else, I feel there's a whole lot to account for regarding how and why personalities are formed and shaped, and that we're probably never going to really understand what goes on. It certainly is interesting subject matter, though.
Doesn't sound like a well designed, rigorous study, but I'd have to read the original article to be sure. Nevertheless, in my case (n=1), I've always considered myself at least above average in looks and I'm a muscular mesomorph. I've been pushing steel for decades and I'm as strong as I've ever been. Yet, I've also always been extremely reserved and extremely introverted. I write but I don't talk (much). I have a suspicion that the investigators in this study found out what they hoped to find out.