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December 31, 2012 / JayMan

All Human Behavioral Traits are Heritable

Edit, 1/3/13: [Post updated to reflect additional information provided in the comments. See below and see the comments.]

The time has come for a little reminder of the First Law of behavioral genetics. In my final post of 2012, I will discuss this extremely important law in depth. As we may recall from debates with creationists about the reality of evolution, scientific “laws” are comprehensive facts of nature that have the virtue of being able to be expressed in a few sentences, typically one or two. The three laws of behavioral genetics are no exception:

  1. First Law. All human behavioral traits are heritable.
  2. Second Law. The effect of being raised in the same family is smaller than the effect of genes.
  3. Third Law. A substantial portion of the variation in complex human behavioral traits is not accounted for by the effects of genes or families.

These laws are extremely important to understanding human behavior, particularly human differences, which is precisely what those of us who study HBD, Human BioDiversity investigate. Anyone who seriously considers this subject should be intimately familiar with these laws, the evidence from which they’re derived, and their implications.

To HBD’ers especially, the First Law is of paramount importance, and is often quite overlooked by the very people who stress heredity in explaining human differences.

But, what does this mean? How do we know this? The First Law emerges from studies of twins, studies of adoptees, and (now) sibling genetic similarity studies. In short, when you look at people’s behavior, virtually without exception (with a few important ones which I’ll soon discuss), you find some effect of the genes on these traits. That is, identical twins reared apart are similar; identical twins are more similar than fraternal twins; biological siblings are more similar than adoptive siblings; siblings who share more DNA are more similar than those who share less. This is not just in the most talked about trait in HBD, IQ, nor is it just in broad personality traits (whether it be the on the Big Five, on the HEXACO, or on whatever model you want to use), but in one’s religious inclination, one’s political views (including one’s thoughts on topics such as abortion, the death penalty, or welfare), career/educational interests, even one’s degree of thinness/fatness (one’s body mass index, or BMI, which is actually 80% heritable, as heritable as height or IQ). This includes even the things that “really matter”: life outcomes, such as one’s chances of completing high school and college; one’s chances of divorcing or getting into trouble with the law; even one’s lifetime earnings. And ask any adoptee that has found their birth family as an adult about the heritability of all manner of odd quirks. Edit: [See this breakdown of the heritability of political stances on specific political issues, adapted from Hatemi & McDermott, 2012, h/t Breviosity.]

How could this be, you may ask? How could such complex and highly specific things be encoded in the DNA and express themselves despite decades of upbringing and childhood experiences? For one, heritability is only probabilistic, not absolute. Few traits are 100% heritable. As well, heritability, as estimated by these studies (even the new genomic ones) can only tell us that traits are correlated with genes. These are points to which I’ll soon return. But, to answer the earlier question, how could these traits be specified by the genes, it is helpful to think how the genes are involved in crafting the brain. First of all, over half of all the genes are expressed primarily or exclusively in the brain. The great wealth of genetic variation that exists in the human species is likely to most manifest itself in one’s intelligence and behaviors. But what does this mean?

The human brain is an extremely sophisticated and incredibly powerful organic computer, unparalleled in ability by anything yet created by man. Yet, like any computer, it is limited in its range of output to given inputs. How these outputs are produced from given inputs depends on the details of its construction, and those details are encoded in the genes. Sure, the brain does respond to environmental input when wiring itself up, and indeed, normal development is impossible without a certain range of environmental input. The development of the human brain is a complex interplay with genes and environment, with each interacting to produce the final product. One would imagine then that this may render heritability minimal, even meaningless; yet, the evidence shows that this is not the case. The reason is that, quite often, these complex interactions proceed in a rather “deterministic” way. There are only a restricted set of possible outcomes, given the initial conditions. These initial conditions being partly specified by heredity. The lateralization of the brain may be one such example. Both hemispheres of the brain are fairly similar. However, human cognitive abilities appear to be highly lateralized, with certain abilities residing in certain hemispheres. It is possible that each side begins roughly equivalent to the other side, but with small biases that become magnified over time. The complex series of feedback loops, while often involving extensive environmental interaction, nonetheless settle on pre-set results as development unfolds. Those of us with receding hairlines (such as myself, unfortunately) should have an idea of how that could work.

But, it’s important to understand the meaning of the term heritability. Heritability is the degree of variation in a studied population that can be attributed to genetic variation in that population. The cause is the variance in question is always due to some genetic difference, but it doesn’t tell you how direct such genetic influence is. It doesn’t distinguish between [gene x + gene y + gene z → A trait] and [x + y + z gene leads to B, which leads to C, which has an effect on D, giving you trait E]. For example, in a population study, a penchant for wearing high-heeled shoes would be highly heritable, but not necessarily because of genes that influence this, but because this is something highly common among those of the sex female. (Of course, a within-sex behavioral genetic study would find that it is heritable in the usually considered sense.)

As well, heritability, as discovered in behavioral genetic studies, only refers to the degree that traits in question correlate with genes with respect to the environmental variation in the study. A study with a restricted range of environmental variation, such as among WEIRD people, will derive a higher heritability estimate than one with a more mixed set of subjects (of course, HBD’ers would argue, correctly, that such samples also have smaller genetic variation as well). The best example of this is height. While height is about 80% heritable in the modern Western world, it is considerably less heritable in the developing world, since factors that influence final height, such as childhood nutrition, are far more variable there than in the West (the heritability of between-group differences, the foundation of HBD, is a point I’ll discuss shortly).

This background environmental variation has big implications for phenotype expression. Just as a seed planted in one type of soil will yield different quality of fruit than if planted in another type of soil, broad environmental changes can lead to large differences in behavioral traits even in the absence of genetic change. This is a sticking point in discussion of heritability of behavioral traits. Certain commenters (such as recently Dennis Mangan and Heartiste) have noted that there have been distinct changes in behavior over the last century, particularly, such as a marked increase in single motherhood, something which is highly heritable today. Like with secular increases in average height, average BMI, and average IQ, this sticking point ignores the fact that the general environment has changed. In the case of single motherhood and divorce, social mores have changed to make this more acceptable, so, those with genotypes more susceptible to exhibiting this behavior have done so, hence, a change in phenotypes.

That said, as racial differences in IQ demonstrate, there is only so much of a difference environmental changes can make. It’s not exactly a straightforward matter to engineer the environment in such a way to get exactly the phenotypes you want with a given set of genotypes. Certain behavioral traits are simply to be accepted as inevitable and dealt with accordingly.

So, how iron-clad is the First Law? Clearly, not all traits are heritable, right? Right. However, there are only a distinct set of exceptions. Traits that are dependent on content aren’t heritable at all. These include what language you speak, in which particular church you worship, what specific political party you identify. However, the degree and manner to which one interacts with these things are very heritable: how proficient you are with language, how church-going you are, how liberal or conservative. In short, genes can’t specify the content, but they can strongly affect how you interact with that content.

As well, traits that result from physical damage aren’t heritable. A person who stutters because of a brain injury doesn’t do so because this was encoded in his genes.

Chromosomal abnormalities, like Down’s Syndrome, also fall into this category. These are merely flukes, and are hence not heritable.

Environmental toxins also lead to effects that aren’t heritable at all. The most well-known of these is lead poisoning, which is known to negatively affect IQ.

As well, recent scientific research has discovered that microorganisms, particularly those that take up residence in the brain, can seriously affect behavior. The poster child for this, the protozoan Toxoplasma gondii, which leads to what’s colloquially known as “crazy cat-lady syndrome”, or toxoplasmosis, occurs when the protozoan infects the brain of a human host, often leading a variety of behavioral changes. Other microorganisms appear to alter our behavior through similar mechanisms. Theoretically, these type of infections would lead to behavioral traits that aren’t heritable at all, as Greg Cochran suspects is the case with male homosexuality. (However, it’s worth noting that even in these cases, differences in behavioral traits may still be heritable, because the infection may only manifest as behavioral changes in individuals with certain genotypes.)

With those exceptions noted, all human behavioral differences show some genetic component, typically a rather large genetic component:

Here it’s worth discussing the probabilistic nature of heritability. Few traits are 100% heritable. As Satoshi Kanazawa noted in his latest post, traits that are simple Mendelian or nearly so have a heritability of 1.0:

Some genetic diseases like Huntington’s disease have heritability of 1.0; genes entirely determine whether or not you will get Huntington’s disease.  If you have the affected gene for the disease, it does not matter at all how you live your life or what your environment is; you will develop the disease.  One’s natural eye color or natural hair color also has heritability of 1.0.  So does one’s blood type.

On the other hand, heritability of 0 means that genes have absolutely no influence on a given trait, and the environment completely determines whether or not someone has the trait.  No human traits have heritability of 0; genes partially influence all human traits to some degree.  (This is known as Turkheimer’s first law of behavior genetics.)

A heritability between 0 and 1.0 indicate that genes only partially predict behavioral traits. Often, this is a sticking point in discussion about heritability, since people seem to be often caught up in a false dichotomy between something being either 0% heritable (meaning not genetically influenced at all) or 100% heritable (meaning genetically determined). Random factors, not the least of which being developmental noise (a phenomenon which appears to be incredibly important), adds a degree of variation in genetic expression. A positive but less than perfect heritability indicates that when you hold genes constant, as you do with identical twins (almost) you still find some variance (but far less so than less genetically related individuals, which is the whole point).

(The sticking point about partial heritabilities isn’t an objective criticism, but is really about changeability. Since we can’t do anything about our genes, people view heritability as a death sentence or sorts—a condemnation to be a certain way. But a less than total heritability appears to leave room for external manipulation, giving hope to these wishes. This is a rather naive view for a variety of reasons, but has no bearing on the reality of heritability of behavioral traits.)

Edit: [In the comments, Henry Harpending has highlighted the work of Peter Visscher and associates. Using population-wide (UK and Norway) genomic analysis from large representative samples, they have affirmed the high heritability of behavioral and physical traits, including IQ and height (traits which are remarkably similar in terms of their genetic expression and heritability). This refutes a common criticism leveled at traditional behavioral genetic studies: that gene-environment correlation is responsible for the observed variation, hence high heritability (e.g., identical (MZ) twins are more similar than fraternal (DZ) twins because people expect MZ twins to be more similar and/or treat MZ twins more similarly than they do DZ twins). These studies get around that problem by looking at unrelated individuals and assessing heritability through genetic similarity alone (akin to sibling genetic similarity studies mentioned above).]

The high and universal heritability of behavioral traits makes standard family and parenting studies worthless. Obviously, any study that tries to examine the effect of parenting and the family environment by studying children and their biological parents will be confounded by heredity. Indeed, I often purposely use the term heredity as opposed to “genetics” or “DNA” to illustrate where the genes come from. There is a reason that the apple doesn’t fall far from the tree. Indeed, The First Law, coupled with the other two Laws, is precisely why we know parenting doesn’t leave a lasting impact on children.

To briefly recap, the Second Law – on the effect of families, is based on the discovery made by behavioral geneticists that the effect of growing up in the same home on behavioral traits is zero. This includes all the traits I previously discussed, including IQ and BMI. These include those “meaningful” life outcome traits, including the money you end up making. In all these traits, children growing up in the same home are no more similar than those growing up in different homes. Identical twins are ~50% similar whether raised together or apart. Adopted siblings are no more similar than random strangers. This isn’t just on paper and pencil intelligence and personality tests, but is visible in deep structural and operational properties of the brain, as seen in this newly released study by Stokes, Turkheimer, et al. All the popular ideas about the importance of parenting collapse when faced with this reality. Contrary to the enshrined conventional wisdom, even in the HBD blogosphere, parenting is simply not that important in the big picture.

(This, of course, is apparently past a certain baseline. Human children appear to need a certain minimum level of support and emotional warmth for normal development, to which Romanian orphanages attest. However, beyond this baseline, extra parenting effort, past what children need to get by, is simply ineffective.)

The Third Law – a substantial portion of the variation in complex human behavioral traits is not accounted for by the effects of genes or families is essentially the left-over variance when heredity and the family environment are accounted for. This value includes measurement error [Edit: see also Staffan's comment below]. It would also include the effects of pathogenic infections or traumatic injury. This value shows that there is considerable variation in behavioral traits even between identical twins raised together. Judith Rich Harris devoted her book No Two Alike to finding an explanation for this unexplained variance. She posits that humans are born with a personality modification system (which coins the “status system”) that molds our behavior to fit the social niche where we are best able to compete. Since twins, who begin life differently thanks to developmental noise, enter slightly (or sometimes significantly) different niches, they can end up being quite different. In the future, I will make a post examining this leftover variance in detail. For now, I will say that, for a variety of reasons – not the least being the aforementioned developmental noise – non-genetic variance doesn’t necessarily equate to changeability, a non-genetic effect can be just as “inborn” as a genetic one.

The First Law, the reality that all human behavioral traits are heritable, has deep implications for HBD as well. For one, HBD’ers often focus on fairly simplistic differences between racial groups, such as average IQ or average future-time orientation. However, since all human behavioral traits are heritable, all differences between human groups could, and almost certainly do, have genetic roots. Indeed, this reality makes it impossible to state that “culture” (meaning non-genetic factors) alone is responsible for any group-wide difference. Indeed, one can only make such an assertion if either:

  • There has been insufficient time for the degree of change to be explained by genetics (as with secular increases in height or BMI).
  • The two populations are genetically identical (possible to declare only if you know that there were no sorting mechanism involved in separating the two populations, as well as no subsequent admixture)

These are usually not the case. Indeed, some researchers in the matter, such as Peter Frost, Greg Cochran and Henry Harpending, and HBD Chick (and of course, myself) pursue this avenue. HBD Chick especially has been prodigious in trying to explain human cultural differences in terms of biology, including the most complex aspects such as politics and ideology. The First Law leads one to be “hereditarian“, and realize that genetics may be involved in explaining even the most seemingly benign quirks that differ between human groups.

Sure, a critic might say that there is no simply conclusive way to determine the degree that heredity plays a role in between group differences as there are ways to determine differences between individuals within a group (yet). But such criticism misses the point. Since we can rarely or never a priori rule out heredity as being responsible for group differences (and indeed, evidence points to heredity typically being involved), it makes sense to research how heritable differences could be behind such group differences.

jesuslandAs political and religious attitudes are heritable, genetics are likely involved in explaining the persistent differences between people within a race within a country, such as between American Whites in different parts of the country. Often, why Whites in different parts in America vote the way they do (instead as some sort of monolithic racial block) seems to dumbfound many commenters. Yet, American Whites seem to have distinct genetic heritage, even among Britons, hailing from different parts of the British Isles and then subject to different selective pressures here in the U.S. In the future, I will publish a post detailing the historical settlement patterns discussed in David Hackett Fischer’s Albion’s Seed and the implications for modern Americans. The reality of the situation is that the persistent and often highly contentious differences between White Americans in different parts of the country, differences that often make it seem like we’re from completely different countries (or sometimes different planets) stem from the fact that American Whites in different regions have different mindsets, and this partly because they have different genes.

In the end, exploring the extent of how heredity drives human behavior and how differences in genetic inheritance explain the vast differences that exist being humans – including between individuals and between groups – will be an active area of research for well into the future (with many such research projects already well underway), and will yield many new discoveries for decades to come (with many projects and belying any notion we’re coming to the end of knowledge in this topic). This is why understanding heritability and the nature of heredity are so key.

53 Comments

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  1. Chris Crawford / Dec 31 2012 7:48 PM

    Jayman, I can agree with all three of your fundamental principles, but I think that the first is too loosely worded. First, there’s the problem of defining “behavioral trait”. I can accept that at some level, but does it apply to a propensity to biting one’s fingernails? Picking one’s nose? A talent for public speaking? An academic bent? Jogging? Stamp collecting? Pronouncing “nuclear” as “nukular”? There are so many tiny elements of behavior that seem to me to be too peculiar, too specific, to be covered by genes.

    Similarly, it’s one thing to say that all behavioral traits have some degree of heritability and another to quantify that. I have no quarrel with the claim that some trait might be heritable, so long as the claim acknowledges that the magnitude of the heritability might be very low.

    Related to this is the statement that “above a certain threshold, parenting doesn’t make much difference.” OK, fine, but where’s the threshold? Among the many parents I know, I can easily perceive differences in the quality of their parenting, as well as the correlations with the outcomes. That threshold might be very high indeed.

    Lastly, I’ll reiterate my dismissal of IQ scores as an indication of intelligence. Belief in the importance of IQ scores reveals a poor appreciation of the complexity of the human mind.

    • JayMan / Dec 31 2012 8:52 PM

      First, there’s the problem of defining “behavioral trait”. I can accept that at some level, but does it apply to a propensity to biting one’s fingernails? Picking one’s nose? A talent for public speaking? An academic bent? Jogging? Stamp collecting? Pronouncing “nuclear” as “nukular”? There are so many tiny elements of behavior that seem to me to be too peculiar, too specific, to be covered by genes.

      Yes, all those things are heritable.

      Similarly, it’s one thing to say that all behavioral traits have some degree of heritability and another to quantify that. I have no quarrel with the claim that some trait might be heritable, so long as the claim acknowledges that the magnitude of the heritability might be very low.

      It almost never is particularly low, though.

      Related to this is the statement that “above a certain threshold, parenting doesn’t make much difference.” OK, fine, but where’s the threshold? Among the many parents I know, I can easily perceive differences in the quality of their parenting, as well as the correlations with the outcomes. That threshold might be very high indeed.

      We’re talking about providing food, shelter, basic human interaction, and not locking your children in a dark room for years on end. The 0% contribution of the shared environment indicates that the minimum necessary amount of parental care must be pretty low, below that which is provided by the parents in these samples.

      Lastly, I’ll reiterate my dismissal of IQ scores as an indication of intelligence. Belief in the importance of IQ scores reveals a poor appreciation of the complexity of the human mind.

      Except that the facts disagree with you.

  2. Chris Crawford / Dec 31 2012 9:25 PM

    Jayman, I have difficulty granting you credence when you make statements that are obviously unjustifiable. Do you really have a study of the heritability of nose picking? Pronouncing “nuclear” as “nukular”? I very much doubt that. I suspect that you’re applying general studies to these particulars. But if you’re willing to make such unjustified assumptions, how can I trust anything you write?

    I completely reject your claim that parents who do nothing beyond providing food, shelter, and basic human interaction produce children who are no better as human beings than the offspring of parents who go further, who provide genuine love, understanding and encouragement. The paper that you claim supports your claim in fact does nothing of the kind; it’s about differences in brain chemistry, not outcomes of parenting. Again, I have to wonder, if you can so completely misrepresent a paper, how can I trust anything you write?

    Your final statement reveals that you equate tautology with evidence. IQ measures intelligence because, lo and behold, intelligence is what is measured by IQ tests. Can you not see how silly the argument is? That’s why I avoid the useless term “intelligence” and instead think in terms of cognitive performance. How well does a person cope with the challenges thrown at him? If he’s a hunter, how successful is he? Does an IQ test measure hunting skills? Has anybody ever correlated IQ scores with caloric production of hunter-gatherers?

    IQ scores do not measure social skills, yet surely you’ll agree that social skills are important to a person’s success in life. I could go on and on, but I think you get the point: the score you get on a test doesn’t say much about the wide array of cognitive talents each of us possesses.

    I have seen the studies purporting to correlate IQ with “success”. The problem here is that there is no objective measure of success in life. Income doesn’t measure personal success. People pursue different goals, and the best measure of their cognitive performance is how well they achieve those goals given the obstacles they faced. How on earth can you measure that?

    • JayMan / Dec 31 2012 10:06 PM

      Do you really have a study of the heritability of nose picking? Pronouncing “nuclear” as “nukular”? I very much doubt that. I suspect that you’re applying general studies to these particulars. But if you’re willing to make such unjustified assumptions, how can I trust anything you write?

      Chris, don’t be obtuse. As I’ve mentioned in the post, and as I’ve previously directed you to elsewhere, for more on the subject, see either The Nurture Assumption or No Two Alike by Judith Harris or The Blank Slate by Steven Pinker. Each contains numerous and comprehensive references which you can check for yourself. If you’re unwilling to do so, please don’t bother to waste my time.

      The paper that you claim supports your claim in fact does nothing of the kind; it’s about differences in brain chemistry, not outcomes of parenting. Again, I have to wonder, if you can so completely misrepresent a paper, how can I trust anything you write?

      First of all, evidence for the null effect of parenting comes from more than this one study. See above.

      Second, the particulars of this brain chemistry shows no shared environment effect, which it would if parenting had any sort of effect. This study is one of many that demonstrate the null effect.

      IQ measures intelligence because, lo and behold, intelligence is what is measured by IQ tests. Can you not see how silly the argument is?

      No Chris, that’s not what it said. Please, enough with the strawmen. IQ is verified as valid measure because it is predictive of real world outcomes! It does not rest on circular logic as you’ve misrepresented here.

      IQ scores do not measure social skills, yet surely you’ll agree that social skills are important to a person’s success in life.

      The disconnect between IQ and social intelligence is primarily a product of the autism spectrum. In non-autistics, social intelligence is positively correlated with IQ, as are all forms of intelligence (that have any predictive validity).

      I have seen the studies purporting to correlate IQ with “success”. The problem here is that there is no objective measure of success in life. Income doesn’t measure personal success.

      Chris, can we let go of the red-herring? Yes, personal “success” is a somewhat subjective term, but the ones who talk about “success” in terms of IQ’s correlation with it clearly define what they’re talking about before hand.

  3. Chris Crawford / Dec 31 2012 11:38 PM

    The link you presented to Wikipedia opened up a lot of issues, so I’ll go explore those and see where they lead. I’ll also go over The Blank Slate again. I read it when it first came out and greatly enjoyed it. I want to check just how firmly it backs up your position, which seems to me to be much stronger than Pinker’s. But I’ll report back on what I find, offering an apology if I have misconstrued your meaning.

  4. Chris Crawford / Jan 1 2013 11:05 AM

    OK, I’ve read everything that Pinker had to say in The Blank Slate about parenting, and I’ve delved a little deeper, and I have some useful things to say. First, I do owe you an apology for an unduly harsh assessment of your statements. I think that harsh assessment arose from some tricky semantic issues involving the distinction between personality and behavior.

    The first law explicitly addresses behavior. As a law, however, it is an induction, not an observation. It represents an extrapolation from a limited set of observations to a broader set of phenomena. This extrapolation is problematic. When we observe that Mercury, Venus, Earth, Mars, and Jupiter obey Kepler’s Laws, it’s a trustworthy extrapolation to apply Kepler’s Laws to Saturn — because it’s exactly the same phenomenon being applied in an different instance.

    Such is not the case with behavior. If we measure an individual’s personality OCEAN values, and find that he scores high on the neuroticism dimension, it is possible that the neuroticism will manifest itself in a variety of behaviors: nail-biting, excessive hand-washing, nose-picking, and so on. But the confidence we can attach to such predictions depends on how closely the behavior is associable with the personality trait. I’m willing to accept the claim that all behavior is heritable, but only in the sense that genetic factors can play a role in all behavior. The extrapolation you make, that genetic factors are responsible (as a rule of thumb) for about 50% of behavior, is reliable only for what I’ll call “base-level” behaviors. I suspect that the more complex or nuanced the behavior, the less effect genes have — but I cannot provide evidence to support my suspicion. I will, however, note that the actual evidence we have does not support the extrapolation of the law to these more complex or nuanced behaviors, because they’re much more difficult to measure. What we have measured is the simpler, more basal-level behavior.

    For the remainder of this discussion, please indulge me in the use of the crude terms “nature” and “nurture”. The first law states that all behavior has some component of nature, and that’s acceptable to me. Claiming that all behavior has a large component of nature is not justified by the evidence.

    The issue with parenting concerns the degree to which parenting — nurture — affects the development of the child. Your claim is that nurture above a low threshold has zero effect, and you assert that Pinker supports your claim. As I read Pinker, however, he’s making a more restricted statement: that nurture doesn’t affect personality. At no point is he this explicit, but the context in which he discusses the matter seems to me to be focused on personality, not behavior. The few studies I followed up on addressed personality, not behavior. I’m therefore willing to accept the claim that nurture doesn’t affect personality. But I draw a line at behavior. If a person chews his food ten times before swallowing, I doubt that he got that from his genes; I would be more inclined to accept the hypothesis that he does so because his mother taught him to do that.

    In this, I am relying on the notion of a pyramid of factors determining behavior. I can’t recall where I read this, but the concept is patent. The foundation of behavior is nature; layered on top of that is nurture; on top of that is immediate context. The higher levels of the pyramid are more proximate in their effect on behavior, and the lower levels are more fundamental.

    I am not accepting the notion that nature determines important behavior. At this point, I’ll provide a specific example to make my position clear. My mother was narcissistic, and sure enough, all four children are also narcissistic. This narcissism powerfully affected my behavior when I was young, but I was fortunate to undergo considerable personal growth under the civilizing influence of my wife. I could not change my underlying narcissism, but I did come to realize its presence and its injurious effects. I learned to throttle that narcissism, to inhibit its expression in behavior. I won’t claim that my personality changed, but my behavior certainly did. While personality is strongly influenced by nature, behavior can be even more strongly influenced by nurture. We are not responsible for our thoughts, but we are surely responsible for our deeds.

    • JayMan / Jan 1 2013 11:49 AM

      OK, I’ve read everything that Pinker had to say in The Blank Slate about parenting

      Good. Though from your comments, I don’t think you did.

      I am relying on the notion of a pyramid of factors determining behavior. I can’t recall where I read this, but the concept is patent. The foundation of behavior is nature; layered on top of that is nurture; on top of that is immediate context. The higher levels of the pyramid are more proximate in their effect on behavior, and the lower levels are more fundamental.

      While there is some truth to this, this isn’t exactly how it works in the real world. Just as g is in part the result of an assembly of lower-order and more specific mental abilities, broad personality traits are themselves a composition of a highly specific set of behavioral traits, many of which happen to be related, giving us dimensional scales like the HEXACO.

      The first law explicitly addresses behavior. As a law, however, it is an induction, not an observation. It represents an extrapolation from a limited set of observations to a broader set of phenomena. This extrapolation is problematic. When we observe that Mercury, Venus, Earth, Mars, and Jupiter obey Kepler’s Laws, it’s a trustworthy extrapolation to apply Kepler’s Laws to Saturn — because it’s exactly the same phenomenon being applied in an different instance.

      Chris, all science is based on induction. That argument belongs in a philosophy discussion, not here.

      I think that harsh assessment arose from some tricky semantic issues involving the distinction between personality and behavior … If we measure an individual’s personality OCEAN values, and find that he scores high on the neuroticism dimension, it is possible that the neuroticism will manifest itself in a variety of behaviors: nail-biting, excessive hand-washing, nose-picking, and so on. But the confidence we can attach to such predictions depends on how closely the behavior is associable with the personality trait. I’m willing to accept the claim that all behavior is heritable, but only in the sense that genetic factors can play a role in all behavior. The extrapolation you make, that genetic factors are responsible (as a rule of thumb) for about 50% of behavior, is reliable only for what I’ll call “base-level” behaviors.

      Chris, reread my post, read chapter 3 of The Blank Slate, or read either of Harris’s books. That is false, you’ve been repeatedly told that it is false, and you have been pointed to evidence that shows that it is false. If you continue with that assertion, I will assume that you are trolling and react accordingly.

      The issue with parenting concerns the degree to which parenting — nurture — affects the development of the child. Your claim is that nurture above a low threshold has zero effect, and you assert that Pinker supports your claim. As I read Pinker, however, he’s making a more restricted statement: that nurture doesn’t affect personality. At no point is he this explicit, but the context in which he discusses the matter seems to me to be focused on personality, not behavior. The few studies I followed up on addressed personality, not behavior. I’m therefore willing to accept the claim that nurture doesn’t affect personality. But I draw a line at behavior. If a person chews his food ten times before swallowing, I doubt that he got that from his genes; I would be more inclined to accept the hypothesis that he does so because his mother taught him to do that.

      See above Chris. YOU are making this false division between broad personality traits and specific behavioral traits.

      I am not accepting the notion that nature determines important behavior.

      Then you are just blind to reality.

      My mother was narcissistic, and sure enough, all four children are also narcissistic.

      You don’t say, Chris…

      This narcissism powerfully affected my behavior when I was young, but I was fortunate to undergo considerable personal growth under the civilizing influence of my wife. I could not change my underlying narcissism, but I did come to realize its presence and its injurious effects. I learned to throttle that narcissism, to inhibit its expression in behavior. I won’t claim that my personality changed, but my behavior certainly did.

      Did you ever watch House, M.D.? Specifically, did you ever see the episode “The Social Contract”? To paraphrase a relevant line from the show, if you make an effort to suppress your tendency to be narcissistic, then that is just as much a part of your personality as is the narcissism.

      Your attempt to draw a hard line against the type of behavioral traits you feel are “broad” enough to be influenced by heredity and those that are specific enough to not be is artificial, and is plainly wrong, as shown by the evidence.

      Chris, you seem to have a preconceived view about the way you think things are, and throughout all my discussions with you, you try to mold the facts to fit your preconceived view rather than allowing your views to be shaped by the facts, as you should. I ask you to review the evidence, and allow it to impinge on your thinking. Please do so before commenting again, because if you make a comment without it being evident that you have reviewed the facts, and instead continue to repeat the same falsehoods you have been, I will have to subject your comments to moderation.

  5. Chris Crawford / Jan 1 2013 12:18 PM

    Jayman, it’s apparent that your frustration with our disagreement is interfering with your ability to calmly assess my claims; you have descended to spending more time questioning my intellect and education than addressing my points, and you rely on blanket denial rather than analysis. I’m disappointed by this, because I love sharp disagreements prosecuted with intellectual integrity; they are the best way to learn. I’ve learned a lot from this discussion, and a goodly amount of serious thought went into my comments, more so than is usually the case with blog discussions. But now it seems that you have crossed an emotional threshold that prevents the continuation of this discussion.

    This statement of yours exemplifies my point:

    “Chris, reread my post, read chapter 3 of The Blank Slate, or read either of Harris’s books. That is false, you’ve been repeatedly told that it is false, and you have been pointed to evidence that shows that it is false. If you continue with that assertion, I will assume that you are trolling and react accordingly.”

    This is an emotional outburst, not a reasoned argument. I suggest that you are too emotionally attached to your beliefs to approach them with the necessary scientific detachment. You’re obviously a bright and knowledgeable person, and this post and its ensuing discussion have served to alter some of my beliefs on the matter. In the fullness of time, after you’ve experienced more of the furnace of intellectual disagreement, I’m sure that you’ll become less emotional, and I wish you well in that progression. Goodbye.

    • JayMan / Jan 1 2013 1:13 PM

      you have descended to spending more time questioning my intellect and education than addressing my points,

      No, I haven’t Chris. I’ve specifically addressed your points, and your apparent refusal to acknowledge the evidence presented to you.

      “Chris, reread my post, read chapter 3 of The Blank Slate, or read either of Harris’s books. That is false, you’ve been repeatedly told that it is false, and you have been pointed to evidence that shows that it is false. If you continue with that assertion, I will assume that you are trolling and react accordingly.”

      This is an emotional outburst, not a reasoned argument.

      Chris, don’t confuse being admonished for your intellectually dishonest discourse with an attack on your person. The two are not the same, and, to use your own view, how do you ever expect to learn and grow as a debater if you take personally any attempts to highlight your incorrect debate approach?

      In any case, you’re always welcome to engage in honest discourse here, should you so choose.

    • Aishwarya Ganeshan / Jan 25 2014 9:17 AM

      From a completely third person’s point of view, Jayman is clearly being extremely disrespectful to Chris, and is determinedly defending his observations with the same rigidity and narrow mindedness that he’s accusing Chris of. Jayman was threatening to pull Chris off the comment thread purely because he thought his comments were “intellectually dishonest” – or in other words, not backed by the evidence HE deems worthy. Shouldn’t you be glad that you’re getting a chance to dispel the “myths” – as you would like to call them – about heritability that the “general public” grapples with? Why were you being so defensive? “You don’t say..” is hardly a mature response to a confession of narcissism on a post about heritability of personality traits.

    • JayMan / Jan 25 2014 9:28 AM

      @Aishwarya:

      The evidence is clearly here and in the references given. They do not support what Chris was saying, and I’ve told him otherwise on numerous occasions.

      Look, the bottom line is that while we may be entitled to our own opinions, we are NOT entitled to our own facts. That is how things will proceed here. If you continue to insist otherwise YOU will face the same fate (moderation/possible banning).

  6. breviosity / Jan 1 2013 12:49 PM

    Political attitudes, and political knowledge, are in good part heritable, with the exception that the shared or family environment seems to be the main influence on political party identification.

    http://breviosity.wordpress.com/2012/08/29/genetics-and-politics/

    • JayMan / Jan 1 2013 1:18 PM

      Indeed. Excellent find! I think that this can likely be explained by the fact that political party identification is an example of local content, one that is typically shared in a region. Hence, the family in which you grow up, in a large sample, would seem to be highly predictive of party affiliation.

  7. harpend / Jan 1 2013 3:22 PM

    Your viewpoint has gotten an important boost in the last few years from the work of Peter Visscher. He estimates remote kinship between people from SNP chips, looking at kinship assayed from millions of genetic markers all at once. Traditional data sources like twins have always been under a shadow because of shared uterine environment, non-random placement of separated twins, and so on. By looking at correlations between remote relatives (who don’t know that they are relatives) those old objections are essentially finished.

    For IQ, see Davies, G. et al., 2011. Genome-wide association studies establish that human
    intelligence is highly heritable and polygenic. Molecular psychiatry, 16, pp.996–
    1005.

    For stature see Yang, J. et al., 2010. Common SNPs explain a large proportion of the heritability for human height. Nature genetics, 42, pp.565–569.

    Henry Harpending

    • JayMan / Jan 3 2013 11:22 AM

      Dr. Harpending, thanks for commenting, and thanks for the heads up! I have edited my post to include this information.

  8. Paul / Jan 2 2013 12:56 AM

    “(However, it’s worth noting that even in these cases, differences in behavioral traits may still be heritable, because the infection may only manifest as behavioral changes in individuals with certain genotypes)”

    It wouldn’t make sense in this case to say that the homosexuality is a heritable behavioral trait of the homosexual. The homosexual phenotype is actually an expression of the heritable genetic information of the pathogen.

    Rabies would be a similar example. A raccoon with rabies exhibits certain behaviors, but these behaviors are expressions of the rabies virus, not heritable behavioral traits of the raccoon.

    You could say that the homosexual and the raccoon have low immunity levels that they inherited and that made them susceptible to homosexuality and rabies, but that’s quite a different thing from saying that engaging in homosexual acts and frothing at the mouth are behavioral traits that they inherited.

    • JayMan / Jan 3 2013 2:22 PM

      “(However, it’s worth noting that even in these cases, differences in behavioral traits may still be heritable, because the infection may only manifest as behavioral changes in individuals with certain genotypes)”

      It wouldn’t make sense in this case to say that the homosexuality is a heritable behavioral trait of the homosexual. The homosexual phenotype is actually an expression of the heritable genetic information of the pathogen.

      If this indeed operates as I’ve said, and a pathogen is producing homosexuality in genetically vulnerable men, it would still be quite heritable, for as I note, with heritablity, “the cause is the variance in question is always due to some genetic difference, but it doesn’t tell you how direct such genetic influence is.”

    • Paul / Jan 4 2013 6:15 AM

      It wouldn’t really make sense to call it a heritable trait of the afflicted individuals, just as it wouldn’t make sense to say that frothing at the mouth from rabies is a heritable trait. They’re more like symptoms of diseases. The pathogens are expressing their heritable genetic information through their hosts. The hosts are the environments of the pathogens. If the pathogens haven’t infected the hosts, the phenotypes aren’t expressed, despite the hosts having the same heritable genetic information. They’re really more like the heritable traits of the pathogens, expressed in the bodies of the hosts.

      “Heritable traits” seem to imply things that have been more directly selected for, and that are more directly and persistently expressed by the organism that contains the genetic information. Drowning in water could be said to be a heritable trait since humans unlike fish don’t have genes for breathing underwater, but that isn’t really the sense of the common usage of “heritable trait”.

  9. Staffan / Jan 2 2013 6:35 AM

    I’m just going to add that personality is more heritable than the numbers above might suggest to most people. It’s not to be interpreted as a 50/50 for nature and nurture since part of this is measurment error. Some textbooks even make this false conclusion. Its more like 50 nature, 25 nurture, 25 unknown. And when you look at something like IQ (which is related to personality) in which the objective result coincide with social desirability you instantly get a much higher heritability of 0.8. This is also the case with ADHD which is basically just a measure of impulsivity. The more accurate measures consistently yield higher heritabilities.

    Also, very specific attitudes like whether you like Jazz or capital punishment have high heritabilities, suggesting that the same would hold for specific behaviors, like playing the saxophone, http://www2.psych.ubc.ca/~schaller/528Readings/Tesser1993.pdf

    • JayMan / Jan 3 2013 11:35 AM

      Absolutely. If that 25% “unknown” was actually “missed” heritable variance, then it would bring common personality traits more in line with the heritability of things like IQ. As per the above chart, the heritability of schizophrenia is also very high, in the 0.8 range.

      Coincidentally, I will add that I am working on a post discussing the details of the Third Law, and looking at just what is involved in that leftover variance. I will say now that the studies I have seen that shows concrete non-genetic effects on personality – while showing them to be indeed real – consistently show them to be small, in the 0.1-0.2 range. This would be consistent with the numbers you’ve noted.

  10. Letra de la Ley / Jan 11 2013 5:12 AM

    You’re to be congratulated for the patience and good humor with which you’ve responded to Mr Crawford, Jayman. The news that he comes from a narcissistic family is up there with news of ursid behavior in silvan environments and of which socio-religious deme the present occupant of the Vatican counts himself a member of. But you could have saved yourself time by remembering this:

    Mit der Dummheit kämpfen Götter selbst vergebens…

    http://www.quotationspage.com/quote/35946.html

  11. namae nanka / Mar 30 2013 3:40 AM

    “In the case of single motherhood and divorce, social mores have changed to make this more acceptable, so, those with genotypes more susceptible to exhibiting this behavior have done so, hence, a change in phenotypes.”

    and schooling has been made compulsory. Tracking outlawed and consider Sailer’s criticism of her work.

    “That said, as racial differences in IQ demonstrate, there is only so much of a difference environmental changes can make. ”

    what about conscientiousness? See for example Grady Towers’ essay Outsiders.
    And early puberty in girls?

  12. coward / May 22 2013 4:53 PM

    One thing I have noticed is that handwriting is highly heritable. The specific loops, slants, and proportion specific to each handwriting is passed on from parent to child. I have noticed this at school, at work, and anywhere else I had to handle parent/child documents.

  13. boogieman / Jun 8 2013 10:59 AM

    So…is cheating heritable? I think to a certain point it is as i have been wondering.. I know my parents both stand-up citizens taught me well and have been a good example as parents, but I know I’m a pretty fucked up individual, I’ve cheated multiple times and have been an abusive person. I grew up in a fairly peaceful environment and I have good parents, maybe i missing something. Then I recently discovered about my grandfather’s (father side) dark past that my parents kept secret, he passed away. He has kids from different “partners” and was also abusive, my parents also used to tell me that I was his favorite grandson. I know i have a choice to certain things right but the desire to do the things my own way is like a force beyond me.

    • JayMan / Jun 8 2013 7:36 PM

      So…is cheating heritable?

      Yup. Also here.

      I’ve cheated multiple times and have been an abusive person. I grew up in a fairly peaceful environment and I have good parents, maybe i missing something. hen I recently discovered about my grandfather’s (father side) dark past that my parents kept secret, he passed away. He has kids from different “partners” and was also abusive, my parents also used to tell me that I was his favorite grandson.

      Indeed. Heredity is amazing…

      I know i have a choice to certain things right but the desire to do the things my own way is like a force beyond me.

      You always have a choice. But the choices you will end up making can be somewhat predicted beforehand. Interesting apparent paradox, yes?

  14. The fourth doorman of the apocalypse / Oct 12 2013 1:11 PM

    I really liked the reference to Asimov

  15. laofmoonster / Oct 22 2013 6:16 PM

    “First Law. All human behavioral traits are heritable.”

    A corollary to this is, “All human behavioral traits are selectable”

    • JayMan / Oct 22 2013 7:16 PM

      @laofmoonster.
      Indeed.

  16. overexcitable / Nov 9 2013 7:32 PM

    Reblogged this on Overexcitable.

  17. Jay / Feb 21 2014 11:33 PM

    what exactly do the racial differences have to say about IQ scores? I’m very curious….. because to think a person’s “race” has anything to do with so called “IQ” is not very smart.

    • JayMan / Feb 21 2014 11:36 PM

      @Jay:

      what exactly do the racial differences have to say about IQ scores? I’m very curious

      Excellent! In that case, there you go:

      HBD Fundamentals

      because to think a person’s “race” has anything to do with so called “IQ” is not very smart.

      To make such claims when clearly ignorant of the evidence is definitely not very wise. Fortunately, that’s easily remedied.

  18. disenchantedscholar / Jul 4 2014 10:17 AM

    Reblogged this on Philosophies of a Disenchanted Scholar and commented:
    reference

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