Much to my surprise, liking rock and classical music predicts the same things about your personality: having greater “openness to experience” (a personality trait from the Big Five framework) and being more intellectual.

Makes sense for classical, but who would have guessed that’s true of rock?

Another surprise to me was that enjoying dance/electronic music, country music, and jazz music predicted similar traits: being more group-oriented (e.g., gravitating toward group rather than 1-1 interactions), being more extroverted, and being more spontaneous.

But each of these 3 groups also stood out uniquely. Enjoying country was associated with being more emotional, enjoying dance/electronic was associated with higher openness to experience, and enjoying jazz was associated with being less attention-seeking than the other two groups.

Enjoyment of both pop music and hip-hop was associated with being more emotional, but pop music enjoyers were more group-oriented, whereas hip-hop music enjoyers were more spontaneous.

All the correlations discussed here are between r=0.3 and r=0.45 in size, so they are moderately large. It would be neat to see whether this generalizes to non-U.S. samples.

You can explore all of these music genre correlations, plus over a million more correlations about humans, for free using PersonalityMap: https://personalitymap.io

This piece was first written on May 23, 2025, and first appeared on my website on May 29, 2025.

(1) In a large study we ran, IQ (measured by performance on intelligence tasks) had a strong correlation with self-reported (remembered) performance on the math portion of the SAT exam (r=0.61, n=714), which most participants would have taken MANY YEARS prior. This suggests that they were neither lying that often nor were their memories (of a long-ago event) that bad. Though I think there was likely some inflation in their self-reported scores, their reported scores contained a lot of signals.

(2) When we asked people how much they agreed with the extremely subjective statement “I feel satisfied with my income” (on a 7-point scale), their responses correlated quite strongly with their self-reported household income (r=0.43, n=639). This suggests that self-reported subjective feelings can map pretty well onto actual realities.

(3) When we asked, “Have you ever been diagnosed with depression by a medical or mental health professional?” it had a reasonable correlation with the level of agreement to the single statement, “I often tell myself that ‘I am not good enough’ (r=0.37, n=509). This suggests that agreement with vague, seeming statements can say a surprisingly large amount about a person.

(4) You might think that even if it’s an anonymous survey, people wouldn’t be willing to admit socially undesirable behaviors or traits, socially stigmatized events, or highly personal things. But, in our experience, many people are willing to indicate that these apply to them. In one study, when asked if they had ever cheated on a romantic partner, we found that 32% of respondents admitted to having done so.  In another, when asked whether, in childhood, an adult in their home ever hit, beat, kicked, or physically hurt them, 26% agreed. When asked if they had been raped, more than 20% agreed. While it’s certain that some people lie, many people are willing to honestly talk about their experiences in anonymous surveys.

While it’s important to be cautious about self-reporting on surveys – people can lie, they may not be paying attention, they may not remember, and they may lack self-insight – in my experience, it often works (perhaps surprisingly) well to tap important traits!

This piece was first written on March 29, 2025, and first appeared on my website on April 24, 2025.

This bell-curve-like shape is a problem for MBTI-style tests because they want to classify each person as either Extraverted or Introverted, either Sensing or Intuitive and so on (usually represented as a four-letter code, like ENTJ or ISFP). But, for each such trait, most people are near the middle. This is why MBTI-style results often change when retested.

What about the Enneagram? While some treat it as more of a spiritual system, it is also often used as a personality typing system. When we use the theory to produce a score measuring how much each person is like each of the 9 Enneagram types, here is what we find:

As we can see, just like with the MBTI-style results, the distribution of scores on each Enneagram type is also pretty close to a bell curve (though the distributions are a bit right-leaning in some cases).

Your Enneagram “type” is simply whichever of these bell curves you’re the most extreme (positive) outlier on. If you’re an outlier on just one, you have a clear Enneagram type.

Depending on the specific Enneagram test I take, I typically get high scores on each of three or four different types, making the concept of an Enneagram type difficult to apply in my case. If you’re like me, you may not have a single coherent Enneagram type.

The gold standard personality framework in academia in the Big Five system. A big advantage it has over other systems is that it assigns you a score on each trait. Like the other systems, we see the traits are close to normally distributed, which for the Big Five is expected:

Regardless of which of these popular systems we use, personality traits are roughly normally distributed, with lots of people near the average and few far from it. MBTI-style tests force you onto one side or the other of each trait (which works best when not near the middle).

The Enneagram, on the other hand, focuses on the one trait in which you’re the greatest (positive) outlier. Finally, the Big Five simply assigns you a score for all five traits – without trying to categorize you.

This piece was first written on September 12, 2024, and first appeared on my website on September 16, 2024.

Before you read this, however, I recommend you read our piece on the Missing Heritability Problem, which provides important context for interpreting this information. Newer, genome-wide association studies tend to get substantially lower estimates for heritability than the twin study figures listed below, and it is still a debate in the field which approach to measuring heritability is more accurate.

Focusing on twin studies, let’s examine estimated heritabilities across five categories: body, mental health, physical health, cognitive/mind-related traits, and personality (including the Big Five personality traits).

You can find high-resolution versions of these charts here:

• Heritability of body-related traits
• Heritability of mental health-related traits
• Heritability of physical health-related traits
• Heritability of cognitive/mind-related traits
• Heritability of personality-related traits
• Heritability of all traits in one chart

Note that here, we are looking at h^2, which represents the “narrow sense heritability”. It measures the proportion of phenotypic variance in a population that is attributable to additive genetic variance. This measure focuses specifically on the additive effects of alleles, excluding other genetic effects like dominance or epistasis. In particular,

h^2 = (additive genetic variance) / (total phenotypic variance).

All of the h^2 numbers in this article come from (or are derived from) papers (or from combining papers). In most cases, these h^2 numbers were calculated by comparing the similarity of traits between monozygotic / MZ (identical) and dizygotic / DZ (fraternal) twins to isolate the additive genetic component. The intuition for how such studies estimate heritability is that the more similar identical twins are in that trait relative to fraternal twins, the more heritable the trait generally is.

Note that h^2 is different than H^2 (broad sense heritability, sometimes written h_b^2 or h_{b}^2), which measures the proportion of phenotypic variance attributable to all genetic factors, including additive, dominance, and epistatic (gene-gene interaction). In particular,

H^2 = (total genetic variance including additive, dominance, and epistatic variances) / (total phenotypic variance).

H^2 will always be greater than or equal to h^2. The two numbers will be similar in cases where the additive genetic variance constitutes the majority of the total genetic variance.

For traits heavily influenced by dominance or gene-gene interactions, H^2 will be significantly larger than h^2. Examples include traits influenced by a few genes with strong dominance effects or complex traits with significant gene-gene interactions.

Note that h^2 values should be considered rough approximations only. Calculating them can be complex and estimates can vary for a variety of reasons, including:

• Differing populations: sometimes h^2 will differ in different human populations due to differences in genetics or differences in environmental influences
• Equivalent environment assumption: if identical twins and fraternal twins don’t “share their environment” to the same extent, that can lead to issues in calculation. If identical twins share more similar environments than fraternal twins, heritability may be overestimated.
• Gene-environment correlations: if there is a correlation between genetics and the environment experienced by individuals, this can bias estimates.
• Differences in the environment: heritability estimates are merely estimates of the percent of phenotypic variation that is accounted for by genetics in a particular environment. If the environment changes, this number can be expected to change. For instance, if everyone’s environment became more identical, heritability would go up because the environment then can’t account for as much variation.
• Simplifying assumptions: additionally, sometimes additional assumptions are made when estimating heritabilities. For example, Falconer’s formula says that h^2 = 2 (r_MZ – r_DZ) where r_MZ is the correlation coefficient for monozygotic (identical) twins and r_DZ is the correlation coefficient for dizygotic (fraternal) twins. But Falconer’s formula makes some assumptions, for instance, that the correlation in traits between twins is not significantly influenced by shared environmental factors, that the effect of genes on the trait is independent of environmental factors, and that assortative mating doesn’t occur (i.e., parents of the twins are not more similar to each other in terms of the trait than would be expected by chance).

Heritability figures will sometimes change as the environment changes. For instance, in an extreme situation where every person has an identical environment, the only variation is genetic. Hence, the more constrained an environment is the greater the heritability.

A common misconception is that zero heritability would imply that genes are not involved. Suppose, though, that in a specific population, everyone has a gene causing trait X (which the environment then modifies). The heritability of X for that population will be found to be 0, even though the trait is caused by a gene!

Now, let’s look at the heritability of all traits in one bar chart:

And here is a list of heritabilities in table form:

Sources:

Yet, the consequences of these simple rules are profound. Various facets of the world are hard to understand without taking evolution into account. Since our brains and bodies (as well as the natural world) were literally crafted by evolutionary forces, without that evolutionary perspective, you’re missing an important angle.

Here’s a list of human traits that seem hard to explain without considering an evolutionary element (along with possible evolutionary explanations for each):

Note: I’m not an expert in evolutionary theory, and none of these theories are provable beyond a shadow of a doubt. It’s important to remember that not all traits we have are evolutionary adaptive (for instance, they could just be vestigial, or side effects of other adaptive traits, or deleterious but not given time to be squashed by evolution, or random genetic drift, or better explained as cultural phenomena). Think of these as hypotheses for why these aspects of ourselves and the world are the way they are.

Possible Genetic Explanations for Things We Observe

• Why we have a sour taste capacity: probably to detect food spoilage (e.g., the bad chicken may smell and taste sour), as well as under ripeness (think of an unripened apple) and excessive levels of acid (think of old wine that has turned to vinegar). Small amounts of sour taste fine (or even good) to us, but more pungent tastes are usually bad.
• Why we have a salty taste capacity: probably because we die if we don’t replenish our salt since we need it for ion/water homeostasis.
• Why we have an umami taste capacity: probably to encourage us to eat peptides and proteins, which are used in many parts of our bodies (e.g., the composition of muscle). This is the most recently discovered taste capacity that seems to have gained substantial acceptance.
• Why we have a sweet taste capacity: probably to encourage us to eat sugars since they have calories that we use for energy to stay alive. It might also exist to encourage us to eat starches (which can taste sweet as they break down in our mouth), but some now argue that there might be a unique starch taste capacity.
• Why we have a bitter taste capacity: probably to detect poisons (e.g., many non-edible chemicals taste bitter, such as pesticides).
• Why we start to like bitter foods more once we’ve eaten them for a while: possibly because our brains initially assume they might be poison, but after eating them for a while, learn they are fine after we don’t get sick (hence why people can come to enjoy black coffee even though most younger people find it disgusting when they first try it).
• Why some plants have psychedelic effects: probably because they are “trying” to prevent animals from eating them (if it’s a plant that does not spread its seeds by being eaten) or because it’s “trying” to get eaten (if it spreads its seeds by being eaten). Different psychedelic effects from different plants on different animals may be more or less pleasant and may or may not be dangerous for survival.
• Why plants contain caffeine: possibly because it seems to be a natural pesticide for some insects, and possibly because it is believed to attract some types of bees.
• Why we have an “itch” sensory system: probably to detect insects crawling on and landing on us (which is really important when you live outdoors, though not so much when you live indoors).
• Why, when something lightly tickles your skin and produces an itchy feeling, the itch tends to grow worse until it is scratched: possibly because while you may be able to detect an insect landing on you, you probably can’t tell if it’s sitting still on you, so the itching sense is reminding you to scratch (i.e., the bug still might be sitting there even if you can’t feel it).
• Why some people throw up in cars: possibly because some poisons cause a mismatch between what you see and what you feel (and in those cases, it makes a lot of sense to throw up to get rid of the poison). In other words, a mismatch between visual stimuli and proprioceptive stimuli would be an indicator that you may have been poisoned and should throw up to expel it. Being in a car happens to produce a similar mismatch of sensory input.
• Why we get sick of foods if we eat too much of them: probably a form of helpful encouragement to eat a varied diet (to get more balanced nutrition) so that we aren’t as likely to become malnourished.
• Why we sometimes have sudden cravings for non-addictive foods: possibly because the body senses we lack a certain important nutrient.
• Why symmetry is typically considered attractive: probably because various problems related to development in the womb and genetics that can affect survival or reproduction can produce asymmetry (in other words, symmetry is a little bit of evidence that a variety of things that could have gone wrong during gestation, didn’t).
• Why people find clear skin beautiful: possibly because some harmful infectious diseases can cause skin issues (though, of course, most skin issues are harmless)
• Why humans usually find babies cute: probably because it causes us to take better care of our babies and children (and our relatives’ children), which causes our genes to spread more effectively down the generations (and on the flip side, it causes us to be better-taken care of by adults when they have genes for liking cuteness – it is beneficial for the genes of both the adult and baby). Of course, that’s not the only force causing adults to treat babies well, and people seem to differ substantially in how value they put on cuteness.
• Why humans find baby animals cute: probably in part because we’ve purposely bred them to look cute to us (especially dogs) but also in part because babies of other species have features that resemble babies from our own specifies (e.g., helplessness, big eyes relative to the head, big head relative to the body, larger forehead, flatter face, etc.). I assume that the people I know who find (non-bred-to-be-cute) baby animals cuter than baby humans are outliers.
• Why there are so many diseases that are only likely to kill us when we’re old: probably because once we’re past the age of reproductive fitness, there is much less evolutionary pressure pushing to keep us alive (though there still is some, because we still might be useful for helping copies of our genes survive in others, such as in our grandchildren who we can help)
• Why obesity is common now in our society but doesn’t seem to have been a long time ago: probably because our drive to eat food (and calorie absorption systems) were designed by evolution for an environment where exercise was a built-in part of daily life, food was much scarcer, and the taste of food was not nearly as optimized for addictiveness as it is today. Hence many factors push us to eat much more than would have been typical. It’s possible that food was “healthier” way back when on average too, but that’s really tough to say, in part because diets now and back then both varied tremendously depending on location, and in part because optimal human nutrition is still not very well understood.
• Why sudden loud noises cause most people anxiety: probably because such sounds were a pretty good indicator of danger 20,000 years ago (e.g., a tree falling, lighting, a loud animal, an angry person)
• Why males are larger than females on average across nearly all large human groups: possibly because males used to battle with each other a lot more than females did (and so there was a sort of arms race in male size), and also possibly because males hunted more often than females (the larger average size of males may be an adaptation, e.g., for spear throwing, where body weight is helpful). Studies apparently show that the size difference between males and females within a species is correlated with the amount that males battle each other over mates, social status, or resources, though I can’t vouch for the reliability of these studies.
• Why your fingers get wrinkly when soaked in water for a long time: possibly to help us grip wet objects better (since according to at least one study, it seems to improve the gripping ability of wet objects) though this certainly could be a coincidence and some researchers argue against it.
• Why faces play such a prominent role in attraction even though most common facial differences have little or no direct useful function: probably because faces encode some other non-face related information (e.g., related to hormone levels and age) and also because they directly code a little bit of information about how attractive (on average) other people may find your son or daughter if you mate with that person (e.g., if birds find large beaks attractive their offspring will survive more if they have large beaks, all else being equal, even if beaks do not help in any other way).
• Why people who are blind from birth make facial expressions for some emotions (especially anger, contempt, disgust, fear, happiness, and sadness) that non-blind people can recognize at least fairly accurately: probably because these six social emotions are generally useful for survival when living in a group across a wide range of environments (by communicating important information to others) and so have been hardcoded by evolution in a form that others can recognize. It’s also possible that the studies that claim this finding were poorly designed, though.
• Why most people seem to have a gut reaction that incest is morally wrong: possibly an inbuilt mechanism to protect people from breeding with close relatives, which would have a much-elevated chance of producing genetic disorders.
• Why people get goosebumps: probably a (mostly) vestigial reaction for adjusting our hair follicles, which was programmed a very long time ago when our bodies had a lot more of it. Hair standing on end makes animals warmer when they are cold and increases their apparent size when afraid, to intimidate other animals (hence why cold and fear can create goosebumps). It may still be a bit useful for warmth because we have some hair on our bodies.

Note: each of these examples is supposed to illustrate a somewhat extreme form of each trait for clarity purposes. Most people who have or lack each trait don’t have a form that is as extreme as is shown in these examples.

1. Extraversion vs. Introversion

“Are you coming out? It’s going to be a huge night! First we’re meeting up with Bill, Harry and Jennifer for drinks. Then stopping by the party to see the whole crew, and after, if we’re feeling it, we’ll hit up Sing Song karaoke. Then we’re hitting the clubs for the rest of the night!”

“Thanks. I appreciate the invite. I’m just going to stay in tonight. I’ve really been loving this book I’m reading. I’ve been looking forward to having the time to finish it.”

2. Conscientious vs. Nonchalant

“I can’t believe how much material this exam is going to cover! I still need to make an outline of all the material, and flashcards. Last time I color coded my outline which worked really well, though it took a long time to make. I might borrow outlines from a couple other people to see how they organize the material. I’m going to be up until 2am tonight at least.”

“Me too…but more like 4am. I have a date with World of Warcraft. You do realize this test only counts for 5% of our grade, right? I might just skip the exam actually.”

3. Social awareness vs. Social unawareness

“Let’s go talk to Sally over there, she clearly wants to get out of that conversation with Bill. Plus, I should introduce her to Ethan.”

“Wait, who’s Sally again…is she one of the new engineers? How do you know she doesn’t like Bill, did she tell you that? And is Ethan even here tonight? Why do you want to introduce them to each other anyway?”

4. Irrationality vs. Stability

“Sometimes life is so intense that I almost can’t take it. I’ll just burst out in tears in the middle of the day and have to hide in the bathroom at work. I wouldn’t have it any other way though, it’s what makes life so meaningful.”

“Crying at work you mean? I’ve done that too actually. I was at work when I found out my sister had died. It was really tough. Actually though, now that I think about it, I finished out my shift since I only had 5 minutes of it left anyway. And I don’t think I cried until later that night when I was at home alone.”

5. Aesthetic sensitivity vs. Aesthetic indifference

“Did you see the colors he painted his walls!? They made my skin crawl.”

“Wait, what color were they? And how is it even possible for colors to make your skin crawl?”

6. Sensitivity vs. Insensitivity

“Please, please don’t use glue traps. Once the mouse is stuck it will slowly starve to death. What if I help you trap it and then we can find a good place to release it outside?”

“Are you kidding me? We’re talking about a mouse! If the stupid thing weren’t so damn fast I’d stamp right on its head with my boots, that would take so much less time.”

7. Anxiety vs. Calmness

“I’ve been worried all day because I’ve been waiting for the doctor to call me with my test results. I mean, I know I probably will test negative, but what if I don’t? I wouldn’t be able to stay in school anymore, and I’m not sure I could afford the medical bills. Even if there is a 1% that I test positive, the consequences would just be so serious that it’s still a big deal. And my chances might even be worse than 1%! I really don’t need this right now, I was already really worried about the presentation I have to give to the CEO at the end of the month. What is life going to throw at me next?”

“Honestly, you just need to relax. What’s the point of worrying about all this? Worrying doesn’t change anything and you’re just stressing yourself out. Like you said, you’re really unlikely to test positive. Everything is going to be totally fine in the end.”

8. Open Mind vs. Closed Mind

“That was the coolest lecture ever, I’m so inspired right now. I can only begin to imagine what it’s like to be Prism, as a visually impaired Chinese Italian non gender binary person who spent fifteen years fighting for the medical establishment to finally recognize the alternative medical treatments that cured his own cancer! Prism has so many interesting ideas about relationships and child rearing too. I’m also really excited now to buy a few books on the diversity of social practices among First Nations people.”

“Seriously, you enjoyed that? That was literally the weirded thing I’ve ever experienced. I wanted to puke when he made us all put our arms around each other in a circle and try to open our ‘inner eye’. What does that even mean? Not to mention that half the people there were out of it on drugs of some kind. And why on earth was that woman practically naked?”

9. Authoritarianism vs. Libertarianism

“If your father wants you to move in with him and your mom, then that’s your duty as their child. Maybe your pastor can give you advice for how to make it a smooth transition.”

“It was my parents choice to have me. Just because they made that choice doesn’t mean they have control over my life. Are you serious that if you were me you would talk to a pastor for advice? Sure, I’m spiritual. But I don’t belong to a church or follow one particular set of teachings, I prefer to figure out myself what religion and spirituality mean.”

10. Optimism vs. Pessimism

“I can’t wait until vacation! We’re going to have such an incredible time together. And it’s going to be such a well deserved break after all this hard work. Plus, they’re going to announce bonuses right before we leave. Business has been great, I bet they’ll be the biggest bonuses yet. When we’re lying on the beach we can discuss the fun things we’re going to buy with all that money!”

“Vacation will be pretty fun I guess. But I’ve been thinking…the beaches get so crowded during the vacation season, maybe it would make more sense to just stay home this year. It’s pretty pointless just lying on the beach all day anyway. I know you’re excited about bonuses, but I don’t want you to get your hopes up. Business looked good this year, but our industry is about to get squeezed with all the new technology coming to market. I wouldn’t be surprised if they don’t even give us bonuses. After all, we work at a company that tries to convince consumers to buy meaningless shit they don’t need, so why would the company care about making its employees happy?”

11. Hypersexuality vs. Asexuality

“This club is amazing…it has the hottest people I’ve ever seen! I would literally sleep with anyone here. It’s hard to even focus on this conversation!”

“Oh…hmm, I guess you’re right, there are a lot of good looking people here. All the skin tight clothing and showing off of skin seems a bit gratuitous though, don’t you think?”

12. Analytical vs. Intuitive

“I’ve been thinking about social interaction a lot lately, and currently my best framework for how to start a conversation with a stranger is to make a comment about something in the surrounding context that you know the other person is already aware of. For instance, about the weather, but only if the weather is well above or below average for that season. Then, once the other person responds to your comment, you should ask them a question related to their response to get them talking further. If the person gives a really short response to your question then it probably means…”

“Can I stop you right there? Honestly, if you’re analyzing how to have social interaction you’re already doing it wrong. Just get a feel for what the other person is like. Then just say whatever feels most natural to say. Don’t overthink everything!”

13. Self-esteem vs. Self depreciation

“There are very few incredible people in the world. What are the chances that two truly unique and awesome people would find each other? I think that as a team we could achieve just about anything.”

“You keep calling me special, but honestly, I’m embarrassed to admit it, but there’s nothing special about me. Nearly everything I’ve achieved was just a result of good luck, or having unfair opportunities that other people don’t get, and I’m probably one of the least talented people to achieve what I’ve achieved. Eventually people will figure that out about me and it will all come crashing down. And when I get good opportunities I usually just mess them up or undermine myself. If there’s anything special about me, it’s that there’s something wrong with me. I screw things up. Fundamentally, not only am I ordinary, but I’m not even an especially good person, and I don’t deserve much of anything.”