Kevin Mitchell on The Genetics of Personality

of the thoughts we have. Quotes like garbage in, garbage out, or you are what you think ring true, and yet for many of us, our thoughts don't strengthen or empower us. We tend toward negativity, self pity, jealousy, or fear. We see what we don't have instead of what we do. We think things that hold us back and dampen our spirit. But it's not just about thinking. Our actions matter. It takes conscious, consistent, and creative effort to make a life

worth living. This podcast is about how other people keep themselves moving in the right direction, how they feed their good wolf. Thanks for joining us. Our guest on this episode is Kevin Mitchell, an author and associate professor of genetics and neuroscience at Trinity College, Dublin, whose research is aimed at understanding the genetic program, specifying the wiring of the brain and its relevance to variation in human faculties.

Kevin is also the author of the science blog called Wiring the Brain and the author of the book discussed here in Nate, How the wiring of our brains shapes who we are. Hi, Kevin, welcome to the show. Thanks very much, thanks for having me. I'm really excited to have you on. We're going to be discussing your book in Nate, How the wiring of our brains shapes who we are. But before we get into that, we'll start

like we always do, with the parable. There's a grandparent who's talking with their grandchild and they say, in life, there are two wolves inside of us that are always a battle. One is a good wolf, which represents things like kindness and bravery and love, and the other is a bad wolf, which represents things like greed and hatred and fear. And the grandchild stops and thinks about it for a second, looks up at their grandparents as well.

Which one wins, and the grandparents says, the one you feed. So I'd like to start off by asking you what that parable means to you in your life and in the work that you do. Well. It's a great question.

And you know, since you had emailed me that link and I looked at it, I thought about it a bit, and actually it really resonates with clearly just you know, in personal life anyway, I think it would resonate with everybody in terms of questions about how we choose actively to live our lives, not just the momentary decisions that we make, but the kind of policies that we have about the types of decisions will make over longer time frames.

And that's something that I've been thinking about, both in the writing of the book and Nate and the one I'm working on now, which is about agency and free will, especially in response to people who look at the fact that, you know, some of our psychological traits have a genetic basis to them, which we'll talk about, and think therefore that there's nothing we can do about it. You know, something is in our DNA and we're just wired that way, and you know, we're not an active agent in that

process at all, And I think that's not right. It's it's true that we are shaped a certain way. We are wired a certain way, but that's only, you know, a baseline, and I think our character emerges through our lifetimes very much based on the decisions that we actively make ourselves through that process. So for me, it struck a chord there with ideas that I've been thinking about

and writing about. Yeah, as I look at your book, Innate and also your upcoming book, which you sent me a proposal for, and I get to read, it feels to me like your work is trying to strike a middle ground owned between on one hand, sort of, as you said, determinism, people who are saying we're just machines and we act out the programs that are put in

us and and that's it. There's no free will. And then on the other hand, what I might call the human potential movement, which says you can be anything you want, right, And I feel like you're kind of staking out a middle position that says, look, you know, there actually is a fair amount of the way we are that's because of the way we are wired. And we're going to talk about how that wiring happens here in a minute.

So a fair amount of it is that, but that's not the entire story, and there is some ability to have control of our thoughts, our emotions, our behavior. Yeah, I think that's right, and I mean thanks for saying that, because I think that's exactly what I'm trying to do, is stake that middle ground, because those two positions you articulated are too extreme. You know, it's not the case that we can just be anything we want to be

or completely overwrite, you know, our innate predispositions. But at the same time, it's also not true that those innate predispositions control everything about us in any given moment, or indeed over the trajectory of our lives. They're not just like you know, the tunings of a robot that will absolutely determine what it does at any moment. They're a baseline for us that does influence the way that we

interact with the world. But I think, you know, one of the real themes of Innate and also the you know, all of the work really is about thinking about the relationship, especially between our genes and our traits as a trajectory. There's not a direct linear correspondence between those things. There's an influence over our lifetimes, you know, in conjunction with all of the experiences that we have and the environments

that we are exposed to and everything else. So it's very much an interactive kind of picture, which in one sense is a little frustrating because it means the pictures just it's not a simple picture, right, you know, it's complex and it's nuanced, but I think it's also just more realistic. And so the debate that most people here is nature versus nurture, right, And that's what we're sort of talking about here. On one hand, it's my genes

or it's my environment, which is it? Right? And I think any intelligent person now would go, well, it's certainly both. But you actually make a point that there is a third component to this that we're missing when we oversimplify down in nature and nurture. Can you share a little bit what that third component is? Sure? Yeah, I mean so that the nature nurture debate, you know, really goes back to the question of whether a child is just born the way they're going to be, or whether they're

upbringing really shapes them. And I think any parents who's had certainly has had more than one child, knows that they come different. They're not blank slates. So the idea that everything about us is shaped by our environment and upbringing just doesn't fit with our common experience. And also the scientific evidence shows that that's just not true. But at the same time, it's also not the case that

the predispositions that are genetics. If you think of nature or as corresponding to genes, which is that correspondence often drawn, that's not the whole picture because you can see two people who have the exact same genes, so identical twins, whose personalities and you know, cognitive and psychological functions may

be clearly different from each other. You know, we can see that in humans, but you can see that in you know, experimental animals in biology and neuroscience, where I mean most of the work that's done on mice, for example, is done on genetically identical mice, and yet there's variation from individual to individual, even in incredibly tightly controlled environmental conditions as well. So it turns out that a lot of that variation just comes from the way that the

brain develops. So if we think within the d n A of a fertilized egg, single cell fertilized egg, that we all start out life as there's a sort of a program, in effect, for making a human being with a human brain, and that program brings along with it the aspects of human nature that differentiate us from chimpanzees or art varks or tigers or any other animal. But you know, the relationship between the information and the genome

and the end product is not like a blueprint. You can't look in the genome and say, you know, it says to make this many cells here, and make those connections like that. You know, there is no sort of correspondence. It's more like a recipe. And the consequence of that is that the recipe doesn't specify the end product. It just specifies a series of processes or steps to make the thing. And so you know, I like to say, you can't bake the same cake twice. It doesn't matter

how good your recipe is. There's going to be some randomness in the way this stuff gets mixed, in the way that it gets cooked in the oven um that produces some variation in the outcome. That's true for our brains as well. The genome just doesn't specify everything about

the way your brain is put together. It just specifies the rules, and then all these complicated processes happen that just have some variability in intrinsic to them, which is then a third source of variation besides genes and environment. Development itself, the process by which you know genetic information is realized to make an individual that adds variation as well. So basically what you're saying is, if you were able to do this, maybe you are able to do this.

For all I know, if you were to take an identical egg in sperm that formed me, and you took both those and you said, all right, here you go go make Eric, what they make would be slightly different. Absolutely yeah, because the path of development would be slightly different,

exactly right. I saw something recently, an article about a woman who was complaining that she had spent dollars to clone her cat, and it turned out she got a pat with a totally different personality and character and everything else, which was sort of funny to me because it was obvious that that was going to happen. You know, what makes us a person an individual is not just our d n A. If it were, then identical twins would be effectively the same person. And obviously they're not. Even

from the moment they're born. The brains of identical twins are already clearly different from each other, and we can see that with neuroimaging and so on. So yeah, right from the get go, there's already some differences in the way that that genetic information gets expressed in any individual run of the program. If we were to group these things nature, nurture and development, though, we would say that

nature genetics development. Those two things are what you would call innate, right, you know, they make up part of who we are. We're not going to intervene in any meaningful way in those things. Yeah, well, I may be taking a leap with that last statement. Yeah, the intervention bid is a slightly separate question, a little trick, and

it's probably not one answer for everything. So what we can do if we want to understand where variation comes from in some say personality traits, right, you know, we can kind of measure various personality traits in different people. And I mean that's a bit arbitrre put a number on things like extroversion or neuroticism, or risk taking or

shyness whatever, you know, all those kinds of things. So say we measured something like that, and then when we look across the population, we see there's a certain amount of variation in the population, exactly the same as if we measured height, and we see, you know, the typical sort of bell curve of lots of people in the middle and fewer people at the extremes. And then we

can ask, well, where does that variation come from? And typically people have thought, well, it must be variation in genes or variation in environment and mathematically you can try and distinguish those and see how much of an effect or how much of a contribution, say, genetic differences make

to those kinds of traits. And when people have done that, using things like twin studies and family studies, what they typically find is that maybe forty of the variants that we see sort of the width of the bell curve if you like, is attributable to genetic differences. And one way to think about as if everybody was a clone, the bell curve would be much much narrower, right right, which you can imagine for height that makes sense, but it wouldn't be zero. I mean, there's still be some

variation left. And then the question is how much of that variation is due to you know, specific experiences or environmental influences or family upbringing versus maybe developmental variation. And one of the sort of surprising findings from a lot of these twin and family studies was that the family environment doesn't seem to affect these traits very much. It doesn't really affect how extroverted or neurotic or conscientious you are,

which was a surprise. And you could see that by looking at people who are adopted, for example, who share no extra resemblance with their adoptive siblings than they do with anybody else on the planet. Basically, I mean, it really says parental upbringing there is not having much of an effect. And even twins who are reared apart sort of the opposite experiment. You identical twins who are reared in different families, and it turns out there about as similar to each other as they would be if they

had been reared in the same family. So the message seems to be that parenting doesn't have much of an influence on those kinds of traits. It's important to nuance that bit because those are precisely the type of traits that psychologists have defined in a way like they're sort

of you know, hardwired biological aspects of an individual. If you know, say fifty percent of the variance is due to genetic differences and then the family environment doesn't make much of a difference at all, then you're left with this question, well, what's the rest. Where's the rest of that variation coming from? And what I think is that a lot of that is just developmental variation. And the upshot of that is that many of those traits are even more innate than it looks like they are just

from the genetics alone. There's a possibility to look at the results from twin studies and say, oh, it's only fifty genetic, the must be experience or environment. But that's not necessarily true. It could be just developmental, in which case a lot of that is still innate. And then we get into other questions about what does it mean to have innate predispositions and how do they influence behavior? Yeah, let's move there next. Let me sum up to where

we are. Now. What we're saying is that you're arguing there's a pretty fair amount of our underlying traits that are innate. What the exact numbers are, nobody knows, but there's a lot of innateness in this, and again anybody common sense would show us to be the case. I mean, there's innateness in dogs, right, I mean you could just tell you've got different personalities, right, absolutely. So let's talk a little bit about what do we mean when we

say underlying traits or predispositions. What are we saying when we talk about those. Yeah, it's a great question and it's a really key to I think undercutting a misunderstanding. So in personality psychology, what psychologists try to do is look for patterns across the behavior of many, many different people, across many many different contexts. So they're really trying to abstract away all the particulars of any individual's life so that they can look for dimensions along which people tend

to vary in their behavior. In the English language, for example, there's about eight thousand words that describe something you would call a personality trait or a character trait or something like that. So you could say someone is is stubborn or strong minded, or strong willed, or obstinate, or well the whole load of other more insulting terms you can use depending on whether they're being you know, positive or negative.

But when you look at those terms, what you find, I mean, the one the examples I just gave you, it's kind of obvious that actually they're all tapping into the same thing. If people vary in stubbornness or obstinacy or any of those other words, really that's all the one thing, right, And so what personality psycholoists have tried to do is say, well, how many things are there

like that? How many dimensions are there that characterize people's behavior sort of independently from each other, That is, the dimensions are independent from each other. And there's lots of ways you can carve that up. I mean, the ancient Greeks had, you know, the four humors of bile and melancholy, and these sorts of things. You can have like you know, two or five or ten or sixteen or thirty different dimensions.

But the most popular ones are the big five extroversion, neuroticism, conscientiousness, which all kind of mean like what the colloquial meanings sound like, and then agreeableness, which makes intuitive sense. And then the last one is openness to experience, which is sort of about imagination and creativity, openness to ideas and and so on, and those things together capture a lot of these basil dimensions along which people vary, and they seem to, in some way that's not well understood, reflect

differences in the way the brain is wired. So really, when you're talking about personality, what you're saying is that people have a tendency to act in a certain way across many different contexts, and really it comes down to decision making. So in any given context, we're going to understand what the context is, use our knowledge and our experience to know kinds of options that we might have.

But then I might, if I'm saying less extroverted than you, I might tend to choose one option more than you would because I'm slightly tilted that direction, if you know what I mean. So that's the way that I think of those as sort of tunings of these basil parameters in the brain. Although if you get into the neurobiology of it, what's interesting is that there isn't clear neurobiology of say, conscientiousness or neuroticism or extra version. There is

a neurobiology of things that feed into them. So risk aversion, for example, is something that we can measure. Even in animal you can measure how risk averse a mouse is compared to another mouse, and we can go into the brain and tweak the neural circuits that we know in some way modulate that and change how risk averse an

animal is. So there's a biology of decision making that has a lot of these underlying parameters, like how sensitive you are to rewards or threats or punishment, how confident you have to be before you make a decision, how long you're willing to wait for a reward, howeverse you are too risks, and how interesting you find novel things. All of those things they can feed into these sort of statistical constructs, which is really what those personality traits are.

So the ideas that we have some of these basil tunings, our brains are really slightly tuned one way or another. And then the question is how does that actually manifest on our behavior on a moment a moment basis. And there I think you have to get into understanding the actual context of particular people in actual city suations, right, because the personality psychology abstracts away all of that idiosyncratic detail. But of course we're never behaving in just any given situation.

We're always behaving in some particular situation and we're not just abstracted collection of personality traits. We're ourselves with all of our knowledge and experience and everything else. And so those predispositions are the starting point. But as we go through our lives, we adapt to our environments. We create

in fact our own environments. We select them over time, and we make decisions about our own behavior and our own behavioral patterns over time, and we develop habits that actually most of our behavior on a moment moment basis is really habitual. You know. We may have habits of behaving one way or another that have been informed over the course of our lives by whether we're more or less extroverted or neurotic, but right now they're not being

controlled by those traits, if that makes sense totally. I want to jump back to something you said there and make a point that I think you make in the book, and I think it's an interesting one, which is you're talking about, say something, a tendency towards more or less risk aversion. Right when we hear that these things are quote unquote genetic, those of us who are at least like me, who don't know that much, think, oh, okay, let's find the gene for risk aversion, and you make

the point that it's a whole lot more complicated. Used to phrase, they're the neural circuits. So talk about the relationship between genetics and something is complicated as a neural circuit, and what do we know about how those inform each

other or create each other. Yeah, so there's two sites that one is something that I've been working on for a long time, and there's a whole field of developmental neurobiology, which is just trying to understand what are the instructions for making a brain, how do they actually work When an embryo is developing, the brain gets set aside, you make nerve cells. They have to be arranged in really really specific ways and different parts of the brain, you know,

all these regions. People will have heard about the cortex and the hippocampus and the cerebellum, and there's thousands and thousands of these. They're all really really very different from each other, and they have their own sort of computational architecture and layout of neurons amount connectivity within them, and then of course they all have to be connected up to each other in really stereotyped ways. So there's basically instructions encoded in the genome that specify at least the

processes by which all of that wiring self assembles. I mean, the amazing thing is it does it itself, right, There's no one in charge telling it what to do. It's this self organizing system. Um and of course that's what you know, billions of years of evolution will will get you. Is this amazing thing, right. But at the same time, because that system develops based on these genetic instructions, and because we all have different genetics, right, because genetic variation

just happens. Every time a sperm or an egg cell is created, some new mutations happened. Genetic variation enters the population, which is why we have diversity of human beings that we see. So what that means is that we then get some variation in the way the brain develops. Right. There may be slightly more cells here, slightly more connections there, and so the wiring of these things differs between people and in some ways that are really really complicated and

complex and not well understood. That wiring manifests as our psychological traits. But you're right in saying that there isn't a very direct or specific relationship. So, first of all, most of our complex behavior can't be tied to one part of the brain or or another. That's really just a sort of an old fashioned simplistic idea saying, oh, you know, I'm doing this with just this part of my brain or that part. It's all circuits, it's all interconnected,

it's it's distributed brain systems. And then you know, on the genetic front, it's also not the case that just one gene specifies one part of the brain. It's loads of genes working together, and so it's complexity all the way down, which is a little bit frustrating if you're trying to, you know, make simple stories. We have a gene for intelligence, or a gene for neuroticism or something

like that. It just turns out that mostly when we find those genetic variants, they're just generally sort of affecting how the brain develops, and that doesn't, unfortunately, tell us an awful lot about the biology of intelligence or social interactions or things like that. Those are really complex things, and the answer to understanding how they work is not in the genetics, even though differences in genes affect them. There's a phrase genetics load the gun, environment pulls the trigger.

Have you heard that phrase before? Yeah, yes I have. What do you think of that phrase? I guess it depends on the context that it's applied to. Okay, say for something like intelligence, right, which is obviously really hot button topic. I would say that people differ in their intellectual potential, and whether they reach that potential is everything to do with education and environment and the opportunities that

they're given. You could say the same for height, You could say the same for athletic skills or musical ability. You know, there's some innate differences between people, but then the environment and experience obviously hugely feed into the actual outcome in any person. So for me, the right way of thinking about it is as an interaction a long or across an extended trajectory, not just a momentary kind

of thing. While in trotting out well known phrases about genetics and neurology, I'm gonna bring out another one, which is neurons that fired to other wire together. Head's law, Yes, which is great. It's attributed to Head, but actually it was a mentor of mine, Carla Schatz, who I think actually coined that term. But the idea is that brains are there to learn, right, So there's nothing hardwired about them. Really,

there's nothing completely hardwired about them. They come they come to sort of pre wired, but they're prewired to learn. And so a lot of the ways in which we learn are one of the simplest ways anyways, by associating two things. So you know, this might be Pavlov ringing his bell and the dog associating with food, right. You know, in the lab it's often a tone and a mouse getting an electric shock or something like that, or an odor.

And you know, so if you pair two things like that, then the neurons that represent them, if they're firing at the same time and they're connected either directly or they're both connected to a third brain area, then they can strengthen those connections. And that we think is in some

way the physical basis for a memory. And you can see that even in the simplest of organisms, things like sea slugs, where they can habituate to their environment or they can learn to associates very simple things over time, and so the neurobiology of that is really well understood. And of course you know in human beings the things we learn over our lifetime. Are you know, things like facts? Right? We learned facts, We learn the properties of objects. We learned that a cat is a type of mammal and

Felix is a particular cat. And you know, so we learned sort of categorical relations between things. We learned causal relations between things. That's how we come to understand the world. We know that if I don't feed Felix, he's going to die, that sort of thing. Sorry for the slightly grim example, but no problem. Felix is done. Felix is done. So we've learned from that the next cat, right, next cat? Yeah, exactly.

So yeah, I mean the idea that'say, neural plasticity. There was a big hulla blue about this, you know, maybe I don't know, fifteen twenty years ago and people suddenly started to say, oh, the brain is plastic. Well, yeah, of course it's plastic. That's what it's for. That's how it that's how it learns. I never could quite understand what the surprise was over that. But again, it doesn't

mean everything in the brain is plastic. It doesn't mean you can overwrite these predispositions that are pre wired in there. But what we do learn is how to adapt to our environments. We learn to do particular behaviors because we know that's a good thing to do in this situation, even if it goes against some of our you know,

innate personality traits. For example, you know, I mean, shy people can learn to be perfectly good public speakers, even though it may exhaust them, you know, as opposed to energizing them in the way that it would somebody else. One of the interesting things I think when we think about the limits of personality traits and the idea that they don't determine our behavior but they influence it, is

thinking about this distinction between personality and character traits. You know, those personality traits that have been defined in the field of personality psychology are designed to be these things that are abstracted away, as I said, from the details of experience. They're sort of overarching patterns, and they're neutral, right, they're not. It's not better or worse to be more or less conscientious, or more or less neurotic, or more or less extroverted.

At least, it's not better or worse in every scenario you could find yourself in. Right, But then there's character traits which are very different, and there are things like the ones that you talked about in the parable of you know, kindness or greed or bravery or loyalty or

temperance or justice, um. And those are things that you know, philosophers have been talking about since the time of Aristotle and Cicero and people like that, and when they've talked about them, there's a moral aspect to them right there. They're seen as virtues or vices. They're good or bad

aspects of our behavior. And it's always been the case again from you know, Aristotle and Cicero on up, that they're not just things that happened to us, right We have a hand in them, We take some control, We have some responsibility for developing those character traits over our lifetime. And again they may be influenced and informed in a certain way by our psychological predispositions, and of course they're

in some way reactive to our environments and experiences. But also we ourselves, you know, make decisions to act in a certain way over our lifetimes, so we're sort of predeciding things, not particular decisions, just ways of behaving that in effect constrain our future selves along a path that

we have decided is a good one. Um. And of course sometimes that's us deciding it, you know, when we're young, it's our parents influencing us, saying, you know, don't know, don't hit Billy or share your food, you know, with Emma, or whatever it is, you know, trying to inculcate some positive character traits and behaviors. And of course there's societal and cultural and for some people religious or other sort of institutional norms and expectations that come into play to

that that informed that arc of character development as well. Yeah, I think that's a really helpful distinction. And you brought up parenting again, and I kind of want to swing back around to that because you said before, look, doesn't appear from the data that parenting has a real big impact on underlying personality traits. But you're not saying that parenting doesn't have an impact on the people we turn out to be in the lives that we live. You're

saying it's not changing that innateness. But obviously we all know if you've got a parent who abuses you, you're gonna have a very different life than somebody who as a parent who doesn't potentially right. Yeah, absolutely, absolutely, And I think that's been a misunderstanding of the surprising result from behavioral genetics that does show parents don't influence those

innate underlying traits. It seemed to indicate wrongly that parents don't influence our behavior at all, or parenting doesn't matter. You know. That was a sort of sort of a shorthand message, which I think is absolutely wrong and just overinterprets the basic result. I think it's exactly as you've said, that parenting, you know, affects all kinds of aspects of our behavior without necessarily rewiring those underlying traits. Those are just the basis, you know, that's just the basement level

of the building. And as we go through our lives, you know, the examples that we're given, the expectations that were set, the encouragement we get, or on the other hand, neglect or abuse or any of the sort of unfortunate you know, negative aspects of parenting as well, absolutely can shape the adaptations that we make, our so called characteristic adaptations to the world, which include ways of being right,

ways of behaving that we call character traits. Once they get sort of crystallized through time, And actually I came across a really nice quote recently which is a bit apocryphal um, but I sawt ascribed to someone named Laosu, who was an ancient Taoist Chinese philosopher, and it goes something like, watch your acts, they become habits. Watch your habits they become character. And then I think it was

what your character it becomes destined? To me, that captured a lot of the idea that we ourselves are making these decisions, and every decision we make can reinforce our own behavioral habits in good or bad ways. So yeah, I think it's true that our genes influence our personality traits, and that our personality traits influence our behavior. But it's not true that our genes determine our traits or that

our traits determine our behavior. And that's the distinction that I think is really important because it gets away from the idea that we have no control that you know, it's just in my d n A. I couldn't help it that way. It's my genetics. That's true only up to a certain point. Yeah, this distinction that we're talking about is one that's of key interest and importance to me, and what we're really talking about, I think is how much choice do I have? How much free will do

I have? And I think this is a really interesting question, And a little background on me. I'm a recovering alcoholic and heroin addict, so I've been in my life in places where it felt like the amount of free will that I had to make a choice felt radically different to me. You know, two days after having had a drink of alcohol, when I'm addicted to alcohol, the amount of free will or choice I have feels radically different

than it does to me fifteen years later. And we could certainly say some of that is just the physiology of what alcohol is doing in my body. But let's broaden that out a little bit and talk about, you know, how much let me say this differently. We can't say, like, well, how much free will does somebody have? Like who's the somebody and what's the circumstance. So talk to me about how you think about that idea of degrees of free

will or choice. Yeah, it's a great question. It's one that I'm really interested in, and it's largely what my new book is about, looking at free will. The question of free will First of all, do we have it at all? Do humans have free will? Is it a real thing or is it an illusion? I think, you know, it's popular these days to kind of say, oh, you know, neuroscience or even genetics or psychology has shown that we

don't have free will. We just our brain makes a decision and then maybe it informs us about it and we make up some reason about it. But really it's all just physical stuff happening in our brains. I think that's not right. I think it is true that we, as agents, and this extends to you know, animals and things as well, really do make decisions, and we really

have causal power in the world as an entity. Right, We're not just pushed around by things in the environment, and we're also not just pushed around by our own parts. We're not just a place where complicated things happen, right.

We're in the driver's seat for a lot of the time. However, that doesn't mean we have complete absolute freedom, right, which is a kind of a non sensical, incoherent notion when you dig into it a bit, as some people would want to say, well, unless I can act unconstrained by any prior cause, then I'm not really free and I don't have free will, And to me, that doesn't really make any sense because acting for no cause also means acting for no reason, you know, on the basis of

no information, just doing things at random. If living organisms did that, we'd never have evolved. The whole point of life is doing things for its own reasons to keep itself going right, And when we come from millions and millions and millions of years of evolution of life that has done that. So living things do things for their own reasons, and that's where agency, I think can be found. You know, if you get into the biology of that, and you get into the biology of decision making, how

do we actually make a decision? Then you can see there's all kinds of things going on, all sorts of different neural systems at play at the same time. So we will, you know, look at a situation and we perceive a load of things. We map what's out in the world. We look for threats and opportunities. We have various goals. We monitor our own internal state to see am I hungry and my thirsty? You know, what do

I want to do? We prioritize some goals versus others, we kind of run through in our minds a set of possible options, and then we weigh them up and decide what which is going to give me the best outcome here, either in the short term or the long term and so on. So there's really really complicated processes going on there, and not surprisingly, those things actually vary

between people. So they vary in terms of say, risk taking, you know, that's a parameter that feeds into decision making and how much control you have, but also the level of sort of rational conscious control that we're each able to deploy. That's a trait that can differ between people, and actually in an obvious way, you can see that it develops across the lifetime because babies, said, don't have

any rational conscious control. It's skill act lee that has to develop and that can be worked on and has to you know, as we mature. But you know, some people are more patient than others, some people are more perseverant than others, and so on. So you know, for me, one of the pieces of evidence that free will is a real thing is that people clearly differ in how much free will they have in a psychological sense. You know,

some people are very able to control themselves. They're not impulsive, they plan over a longer time frame, they're able to prioritize longer term goals over shorter term ones, and so on,

and other people um the opposite. But then also, you know, depending on our situations, if we're tired or hungry, or if we're intoxicated, or you know, any any of those things, of course they can change that, right, So the amount of freedom that we have is also determined by our current state, and then of course by environmental factors as well. You know, the number of options that we have at any given time can be curtailed in lots of ways. And you know, when it comes to things like addiction,

then you're really really are curtailed. I mean, your capacity for rational conscious control really is inhibited by this overwhelming drive that's feeding into these decision making processes and just pushing, pushing, pushing towards getting that absolutely prioritizing that one goal over everything else, even if there's a harmful outcomes, and you know, changing the way that you weigh reward and punishment and

all those kinds of things. So I think the biology of free will once we get past this sort of philosophical do we have it or not, which to me is just a kind of a red herring. It's clearly we do have, you know, the capacity for it. Then we get into more interesting discussions about well, how does it vary? What are the things that can impinge on it or inhibited? Addiction is one of those. I think it just is a very easy to understand. And when I say understand, sort of, I mean visualize what we're

talking about. Addiction is tremendously difficult to understand as an overall phenomenon, but we can see, you know that an addict is clearly being driven by something you know. And so it's so interesting because what I loved about reading your one book and your proposal for the other book, which I can't wait till it comes out, because I love the way you arrive at we do have free will. There's so much of that was so fascinating. We just

don't have time for. But one side, one extreme says well, just choose not to use the rug, right, just choose not to do it, And there's some truth in that. There is ultimately a choice being made, right, I'm choosing. The flip side says, I'm an addict. I'm out of control. I can't do anything about it. And the truth is somewhere in between. And is somebody who has been around people who have addictions most of my adult life and

have had them a couple of times myself. I'm I'm so fascinated in what are the levers that are actually at work there? You know, Like, if I could have an answer to to one question, well, actually, I'm not going to say that there's a thousand questions I want the answer to, but one that would be up high on the list would be why do some people recover

and others don't. I don't understand it, you know, because I've watched people I care about deeply die, you know, from the same disease that I have recovered from, and just don't understand it. But getting some insight into what some of those levers are I think is really interesting. Yeah, And let me prep is this by saying, I'm not an expert in addiction biology, but I have some familiarity

with it. But I think one of the key things to keep in mind is, you know, not to put all of the emphasis on the individual right, because of course there's the social context and the environment that's so so crucial and maybe absolutely a determining factor in you know,

whether somebody does recover or remains addicted or worse. So I think that's the first thing is to say, even if there are genetic and neurobiological aspects to this, it's important not to say, well, that's where the explanation, the complete explanation is right now, having said that, there are some differences between people, and there is a genetics of addiction, right, you can you can do you can study the genetics

of that. So a tendency towards addiction actually sort of a general tendency for any you know, alcohol or tobacco or um, you know, opiates or or other sorts of drugs. There does seem to be a general nderlying factor that makes some people more likely to develop addictions than others. Now that's given that they're exposed. You know that the opportunities are there to have these drugs and whatever other

social factors are in there. So all of that is sort of averaged out if you will, and then you can see there's some genetic differences at work, and you know, some of them are really very specific. They actually affect the genes, say for metabolizing alcohol. So there are people this is a trait that's common in East Asian Japan in particular, people who can't metabolize alcohol well it builds up as an aldehyde that it makes them feel really sick,

and it's actually protective. That variant is protective against developing alcoholism, because you feel so bad when you drink alcohol that those people just tend not to um. So there's a few sort of specific genetic variants like that that affect the proteins or the enzymes that actually metabolize the drugs, or the receptors that see in the neurons that that actually you know, like opioid receptors or nicotine receptors and

so on. But then there's also a really broad kind of what they call polygenic effect, which just means loads and loads of genes are involved, which seems to feed into this general addictiveness personality trait, if you will. The biology there is just really not known. It's probably pretty generic and kind of complicated, and I'm sure it won't come down to, you know, one particular pathway. You know, it won't be just like dopamine signaling or something like that.

It'll it'll be more complicated. Yeah, I was going to ask, and I think you just answered the question, But I was going to ask, when you look at some of those things that make people more susceptible to addiction. You know, we could broadly look at addiction. You know, we're seeing too two broad types of it. One is addiction to substances, right, and then the other is addiction to behaviors gambling or

video games, your shopping, right. And sure, as you were talking, I was thinking, I wonder, you know, is that genetic predisposition lead to both of those equally or one versus the other. And I think, as you said, it's kind of complicated. But any thoughts on that. So there's an interesting paper just came out this week actually looking at this sort of general addiction factor, but it was substance addiction.

I don't know whether the genetics or the neurobiology has in any way distinguished something like a gambling, you know, addiction the tendency towards that, or you know, like you said, the you know, addictions to shopping or Instagram or Twitter, or you know, any any of these other things that that are just behaviors that we that we develop. You know, my guess is that all of those things will have an input from lots of different personality and character traits.

You know, how sensitive we are to rewards, how willing we are to take risks, how impulsive we are, how conscientious we are about planning, you know, over longer term, prioritizing longer term over short term gratification. All of those things will eating and probably in different profiles, in different

ways and different people. So I think, yeah, I mean, the the upshot is that probably won't be any simple kind of linear relationships between genes and those behaviors, right, and the data between the role of adverse childhood experiences on you know, future addiction risk seems pretty clear. Also. You know, one of the things I think a lot about is and we kind of keep circling it, but I do work with coaching clients and a variety different things,

is this idea of tendencies versus predispositions. Like I'll have people come to me and say, I'm the kind of person who X, right, And while there is value in recognizing your tendencies, there's also value in recognizing the ability to go beyond those. Yes, yeah, absolutely, And I think

you know it's one of the interesting things. So some people would say, in talking about again about human free will, that we just have these traits, our brain is just wired us in way, and they would even say that, you know, we do things for reasons that are unknown to us and unknowable. We can't know why we do things. And also they'll say that, you know, my brain is wired just to do these causes that I had nothing

to do with. So, first of all, that's wrong. I think, you know, as we talked about in terms of character development, we as agents play an active part in that throughout our lives. And secondly, the idea that our reasons are just opaque to us, that we can't know them is also just clearly wrong. I mean, those huge parts of our brains are devoted to reasoning about reasons, to thinking about our own thoughts, and we can express our motivations to other people. So it's very clear that we do

have access to a lot of our motivations and reasons. Now, it may be effortful, we may be wrong sometimes, but but we're not wrong all the time. You know, we're actually really good at that, and in fact, we're really good at understanding other people's motivations. That's what a lot

of social cognition is all about. We're really hyper specialized as a hyper social species for precisely that kind of cognition of reasoning about reasons and so what I think that gives is access understanding those things in the first place. Knowing that you have this kind of trait is super useful. So knowing that you're saying a procrastinator is really really helpful if you can then actively put in place behavioral aids.

If you will that you know you're not going to do this task next week, You're you know you're going to put it off and do something else instead of it, So you make yourself put something in your calendar so you absolutely have to do it, and you know you develop the discipline to do that if you can. I mean, I'm terrible at that, but but I try so clearly, not too terrible, because you're fairly well, Um yeah you'd be surprised, but yeah, but I think you know, all

of us can try to do that. And for me, the key thing is in recognizing I'm not going to change my tendency to procrastinate, but I and put in place behaviors that allow me to adapt to that so that it doesn't drive me and have negative consequences in my life, right, and that I think is the key thing.

So if we're thinking about you know, kind of self help and personal development, pushing against yourself or thinking that you can change those underlying predispositions, to me, that's a futile exercise and it's only going to lead to frustration

and a kind of a cycle of bad outcomes. Whereas recognizing what they are and recognizing how they impact on your life and then saying well, I can prevent that impact by doing a B and C. To me, that's a much more positive and much more practical and effective way to approach things. I love what you said there in one way of thinking about that again, you know, making everything about me which is just for illustrative purposes.

I think that I have an underlying well, I know I have an underlying tendency, which is if I take a substance, I'm probably going to want to take it all the time. I don't think that's going to change. The times I've thought it would change, I was wrong by and I've learned that through hard experience. So there are things that I can do that make that far less likely to be a problem, or to use another example,

I have a terrible memory. It is appallingly bad, right, And I think that's one of those things that you would say, is you know, there's some genetic basis to to some of that. So, Okay, I've got a bunch of systems in place that just means I don't have to rely on my memory. Other people who've got a good memory might be able to. I just learned like, it's not gonna work that way. So I think, you know, knowing our tendencies and then devising strategies. And I love

what you said earlier about addiction. I didn't get a chance to comment on it. Which is the environment and the support that's around us. Those things are so so critical. You know, when I look at why did I get sober and other people didn't at the same time as me, Some of that I look at and I go, it was the support systems that I had. It was my socio economic class. I mean, there were supports that I had under me that a lot of other people simply

did not have. Yeah. Yeah, And I think, as I said, I don't have a lot of professional expertise there, but certainly from my general understanding, I think that that's exactly right, that those sorts of social supports are key, you know, in terms of knowing that you have a tendency, that one has an a tendency, a tendency towards wanting to take a drug, if you take it, you know, wanting

to take it again. Then you know, the steps that you can take is make sure that you're not in the situation where those things are about right, you know, So you're preempting you know, you know that you're going to give into temptation if it's there. I don't mean you in particulars um and so you're you're just taking preemptive steps ahead of time to make sure you're not in the situation where you're exposed to that kind of

temptation or or the opportunity. So yeah, I think those aspects are things that people can control in principle at least in practice. Some people may be able to control them better than others for reasons of their own biology or for reasons of sociology on the environmental context and the amount of freedom that they have to create their own environments themselves. Yep, there's a line that you wrote that I really loved and this sort of summarizes I think a lot of what we're saying in a pretty

short way, which is the slate is most definitely not blank. Right, We're not blank slates, That's what you're saying. However, you say slates don't have to be blank to be written on, and I think that summarizes it really well, like, yeah, of course we're not a blank slate, and the slate can still be written on. Yeah, thanks for saying that, because that, to me does sum it up. And like you said, it's a middle ground, which I hope is

the realistic position. You know that the two extreme positions of either complete freedom or total determinism are both false and there's a much more nuanced, interactive kind of story to be told. And it's a story that we're telling ourselves, right, I mean, we're very much the authors of our own

stories in an ongoing way. We start with some sort of predispositions and so on, but we become ourselves through our lifetime that we we go on becoming ourselves in ways that we have a large input to as well. In your latest book, you're talking a little bit about why you think we have free will. And you say that the nervous system allows multiple signals to be simultaneously parsed and processed multiple, perhaps conflicting naimes must be weighed

against each other and an action selected. And that made me think because I was just reading some paper a couple of weeks ago from an evolutionary psychologist who said that something similar to that. They think that's what emotions are. Emotions job is to help us sort out when some

of these multiple subsystems arrive at a draw, so to speak. Right, like, one subsist and says do this, the other subsystem saying no, I don't think so in another one's like, wait, you know that emotions then arise as a way of deciding among those. As I read that line from you, I was kind of curious if you've heard that theory, and does it make sense to you? Yeah? Absolutely so. A way to think about this is think of the function of the brain. It's not for thinking. We use it

for thinking, but it didn't evolve for thinking. It evolved for control, right. It involved for controlling us in a way that allows us to persist and actually, in the simplest sense, parts of our brain that control our physiology are rebalancing when our internal physiology goes a little out of whack, you know, they release hormones, they say, hey, you know you need to do this, you need to

do that. And some of the ways that we ensure we keep persisting our behavioral So behavior is part of this control process, and it's obviously goal directed, and the overarching goal is to keep us alive in an evolutionary sense, to you know, keep us reproducing and so on. So if you think about that as a control system, then within that what you're going to want to have as some control signals that can specify certain drives. And I

think the emotions exactly convey that kind of information. And so some of them are really powerful ones like fear and pain, for example, which can actually just say, you know, ignore everything else, stop ruminating about what decision to make here, rung, that's just just rung. That's it. So it's just like the signal is, don't do anything else. I'm taking over

your running. That's it. And then you know, other ones, the sort of physiological signals like hunger and thirst, those are very much control signals as well, and what they do, I think is prioritize, so they upweight some of these possible actions because they upweight the drive that they're associated with versus all the others. So if you're very hungry, you'll be inclined to go and get something to eat.

But for example, say you're an antelope approaching a watering hole and you're worried there's a line around, Well, then maybe your hunger will win, maybe your fear will win. And so these are balancing signals and so in some way they're you know, these internal control signals that basically are correlates of the weight of different drives that we have.

So it's a sort of a monitoring our internal states as well as what's out in the world and saying, you know what, we need to prioritize this over that. And then the sort of you know, the conscious control can kick in if we're choosing to exercise it and we have that capacity in the moment, and of course, you know, sometimes we do and sometimes we don't. And again, some people are more driven by the short term emotions

that they have. Again, like children, right, I mean, children are very driven by the short term emotions that they have. But as we get older and mature and we develop the skills of cognitive control. We become better at just kind of surveying those emotions and using them as one input in our decision making, rather than letting a single emotion drive you know, an action selection. Excellent, Well, Kevin,

thank you so much. I've loved this conversation. I loved the book, and Nate, I loved the work you're doing on the upcoming book. I can't wait to see it, and thank you so much for coming on. Thanks billion, It's really a pleasure and super interesting conversation. Eric. Thanks. If what you just heard was helpful to you, please consider making a monthly donation to support the One You

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