Genes are overrated, genetics is underrated

By Razib Khan | May 16, 2012 12:53 am

A few days ago Nathaniel Comfort pointed me to this post, Genetic determinism round-up. If you are curious go read Comfort’s whole post. I honestly didn’t enjoy it very much, I think I got what he was saying, but there were all sorts of circumlocutions around the overall message. But I agree one one thing in particular: an emphasis on concrete and specific genes for traits is a motif in science journalism that can be very frustrating, and often misleading. Nevertheless, that’s not the only story. I believe our current culture greatly underestimates the power of genetics in shaping broader social patterns.

How can these be reconciled? Do not genes and genetics go together? The resolution is a simple one: when you speak of 1,000 genes, you speak of no genes. You can’t list 1,000 genes in prose, even if you know them. But using standard quantitative and behavior genetic means one can apportion variation in the population of a trait to variation in genes. 1,000 genes added together can be of great effect. The newest findings in genomics are reinforcing assertions of non-trivial heritability of many complex traits, though rendering problematic attributing that heritability to a specific set of genes.


So how do we underestimate genes? Consider this story in The New York Times Magazine, Can You Call a 9-Year-Old a Psychopath?:

For the past 10 years, Waschbusch has been studying “callous-unemotional” children — those who exhibit a distinctive lack of affect, remorse or empathy — and who are considered at risk of becoming psychopaths as adults. To evaluate Michael, Waschbusch used a combination of psychological exams and teacher- and family-rating scales, including the Inventory of Callous-Unemotional Traits, the Child Psychopathy Scale and a modified version of the Antisocial Process Screening Device — all tools designed to measure the cold, predatory conduct most closely associated with adult psychopathy. (The terms “sociopath” and “psychopath” are essentially identical.) A research assistant interviewed Michael’s parents and teachers about his behavior at home and in school. When all the exams and reports were tabulated, Michael was almost two standard deviations outside the normal range for callous-unemotional behavior, which placed him on the severe end of the spectrum.

Currently, there is no standard test for psychopathy in children, but a growing number of psychologists believe that psychopathy, like autism, is a distinct neurological condition — one that can be identified in children as young as 5. Crucial to this diagnosis are callous-unemotional traits, which most researchers now believe distinguish “fledgling psychopaths” from children with ordinary conduct disorder, who are also impulsive and hard to control and exhibit hostile or violent behavior. According to some studies, roughly one-third of children with severe behavioral problems — like the aggressive disobedience that Michael displays — also test above normal on callous-unemotional traits. (Narcissism and impulsivity, which are part of the adult diagnostic criteria, are difficult to apply to children, who are narcissistic and impulsive by nature.)

The benefits of successful treatment could be enormous. Psychopaths are estimated to make up 1 percent of the population but constitute roughly 15 to 25 percent of the offenders in prison and are responsible for a disproportionate number of brutal crimes and murders. A recent estimate by the neuroscientist Kent Kiehl placed the national cost of psychopathy at $460 billion a year — roughly 10 times the cost of depression — in part because psychopaths tend to be arrested repeatedly. (The societal costs of nonviolent psychopaths may be even higher. Robert Hare, the co-author of “Snakes in Suits,” describes evidence of psychopathy among some financiers and business people; he suspects Bernie Madoff of falling into that category.) The potential for improvement is also what separates diagnosis from determinism: a reason to treat psychopathic children rather than jail them. “As the nuns used to say, ‘Get them young enough, and they can change,’ ” Dadds observes. “You have to hope that’s true. Otherwise, what are we stuck with? These monsters.”

These differences, researchers say, are most likely genetic in origin. One study calculated the heritability of callous-unemotional traits at 80 percent. Donald Lynam, a psychologist at Purdue University who has spent two decades studying “fledgling psychopaths,” says that these differences may eventually solidify to produce the unusual mixture of intelligence and coldness that characterizes adult psychopaths. “The question’s not ‘Why do some people do bad things?’ ” Lynam told me by phone. “It’s ‘Why don’t more people do bad things?’ And the answer is because most of us have things that inhibit us. Like, we worry about hurting others, because we feel empathy. Or we worry about other people not liking us. Or we worry about getting caught. When you start to take away those inhibitors, I think that’s when you end up with psychopathy.”

I have already expressed my lack of awareness on these issues because of how much I trust the understanding of psychologists of any given endophenotype aside from IQ. But let’s say they understand the trait of pscyhoopathy. And let’s take the 80 percent heritability seriously. What does this mean? I’ve rehashed heritability and such 1,000 times on this blog, so let’s go visual with few words. Imagine a scenario where a person who is 2 standard deviations above the norm in psychopathy marries someone who is 1 standard deviation above the norm (roughly, top 2% and top 15%). Assortative mating is common, so this isn’t an out of the ordinary conjecture. Below are the distributions of outcomes of the offspring of these two individuals compared to the general population.

Very few people in our society think in these terms. Rather, very well educated and rich people are spending $30,000 per year on gaining the admission of their 1 year old child to a preschool for toddlers! Unless elite university admission is somehow tied in to this initial admission decision, in utero, I assume these parents are wasting their money, and I’ve wondered how to get some of it myself, as some people are obviously easily parted given moral panic. But their children are not getting a $30,000 “enriched” environment. Environment can only do so much.

So here are two bullet points to repeat:

- For behavior genes don’t matter, genetics does

- When you remove environmental variation, all you have left is genetic variation

Internalizing this reality allows for some “quick & dirty” social science approximations.

CATEGORIZED UNDER: Behavior Genetics
MORE ABOUT: Behavior Genetics
  • marcel

    The paper linked to here is relevant to this. Nothing at variance, I think (at least from the write-up I link to), with stuff you’ve repeated on many occasions.

  • Siod Beorn

    In that graphic, where would the distribution peak of the offspring be for 100% heritability and 20% heritability? Also, does that graphic represent outcome at birth or outcome of life? I.e., how does environment affect the psychopathy distribution in life outcome of the offspring, and how likely is it to do so?

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    100 would have the expected value between the 2 parents. right now it is regressed back to the mean. 20% would be much closer to the mean, about 0.3 units above.

    Also, does that graphic represent outcome at birth or outcome of life? I.e., how much can environment adjust the psychopathy SD of the offspring, and how likely is it to do so?

    this is just the expected distribution of given the environmental average out there. perhaps a better way to think about this is that the offspring distribution is the aggregate of all the offspring of a very large number of 1 sd X 2 sd pairings. in any individual case you may be able to make environmental intervention.

  • dave chamberlin

    I really hope this thread or the ideas within it are spread far and wide. It really is a beautiful piece of science writing, it simplifies without distorting an incredibly important concept that most people just don’t get. How many times have we read “no gene found to correlate with higher intellegence so maybe”…. then the conclusions become just plain stupid. It won’t bring an ephiphany moment to your loyal readers but it sure could to others.

  • April Brown

    I think here you have the sequel for Natural Born Killers, predicting how all of Mickey and Mallory’s kids turned out. (Plot twist – one of the kids ends up at a 30,000 dollar a year preschool, and the others don’t. Compare/contrast. Sell screenplay. Market movie to well educated rich parents. Profit!)

  • Nihaya Khateb

    I agree that there are no spesific set of genes for any mental trait. But I don’t understand what is your model for explaining the heritability of these traits. I don’t agree with your statement that: ” for behavior genes don’t matter, genetic does” We should not seperate between the tow items becaus it is very simple scientific fact: genes = genetic, but not in the sociobiologic meaning of Wilson, rather in a complex new meaning (my model). I can put it another way: For behavior genes matter only at first, then the brain just matter.

  • Justin Loe

    Dr. Robert Hare of Canada is one of the leading, if not the leading expert on psychopathy: http://www.hare.org/. Although this is not my primary area of interest, his articles are a good starting point for those who are interested in the current state of psychological research in this area.

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    but not in the sociobiologic meaning of Wilson, rather in a complex new meaning (my model)

    stop being so narcissistic. we don’t know who you are, and most of us don’t care about your model. we use words as they are used in the common parlance. you’re not particularly clear in your prose, so self-reference is particularly frustrating when trying to understand you. if you FB message me to complain again i will ban/block you without any other prompting.

  • http://theunsilencedscience.blogspot.com/ nooffensebut

    If psychopathy is an example of a “complex trait” that does not depend heavily on one specific gene (granted that you were making a hypothetical assumption that the trait is well understood), why not go one step further and say it does not depend heavily on one specific neurotransmitter? Why not doubt the usefulness of risperidone?

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    why not go one step further and say it does not depend heavily on one specific neurotransmitter? Why not doubt the usefulness of risperidone?

    http://www.gnxp.com/blog/2010/02/small-genetic-effects-do-not-preclude.php

    this is a widely discussed issue in the field. small GWAS effect size/particular genetic architecture does not entail the step you are implying. one could explore the biochemistry aspect for why, but the empirical reality is a lot of people are putting their hope in GWAS less for finding large effect alleles, and more for possible pathways to target with biomedical research. this should tell us how 23andMe eventually wants to leverage their database of trait-snp associations….

  • Todd S

    I agree with your perception that public awareness is unduly narrowed to inaccurate scientific beliefs. I think you convolute the point you’re trying to make. For example, for your readers you need to define heritability (the proportion of a trait that can be explained by genetics, aka by some combination of distinct variants of common genes that are often shared between individuals in a population) and explain that it is a relative metric even though you say you’ve talked a lot about it in the past (that’s just lazy writing). The perceived heritability of a trait could be increased by reducing the variation in the “environment” that also can affect the trait (aka doing a better controlled experiment) or the perceived heritability can be decreased by including a more diverse sampling of individuals from different environments in the data set while compensating for genetic differences known between the individuals. People who study human genetics have statistical methods of dealing with these issues but really the most power comes from family pedigrees and twin studies.

    GWAS (mentioned by someone in the comments here) or genome-wide association studies do not estimate heritability and in many ways GWA studies *assume* there is a genetic component and not necessarily heritable. And using some fancy statistics and reasonable (although not necessarily accurate) assumptions about their data sets, determine an odds ratio for every allele or gene variant they test for ASSOCIATING with the trait of interest.

    Journalists toss around a lot of genetic-y words that are related to each other in the way that a duck and a goose are related to each other without telling people they’re equivocating the two distinct functional identities in some way. At the core of this scientific journalism sucking, I think the problem is how general biology education is constructed from very early in school to very late. The only thing that matters for the general population to know is genetics. The rest of biology is a boondoggle or window-dressing. Genetics is the basis of their future medical treatment options, the basis of pharmaceutical research on how to inhibit enzymes/proteins to alleviate future disease, the basis of almost all ways that basic biology research leads to lifestyle improvements for the general populace. Yet there is still an overemphasis on biochemistry and molecular structures in our society because they are easy and require less explanation on the part of the author. Until we overhaul general biology education to be biased towards genetics our journalism will suffer.

    Lastly, you should also point out that when you remove genetic variation, all you have is environmental variation (of which heritable non-genetic variation i include as “environmental” as it relates to the environment, aka context, in which the genetic material is located).

    Man, i’m surprised really that the Daily Scan at GenomeWeb picked this up; must be a slow news day.

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    For example, for your readers you need to define heritability (the proportion of a trait that can be explained by genetics, aka by some combination of distinct variants of common genes that are often shared between individuals in a population) and explain that it is a relative metric even though you say you’ve talked a lot about it in the past (that’s just lazy writing).

    hey dumbass, before you leave a long patronizing comment, perhaps you should check to see if i’ve talked about this before:

    http://blogs.discovermagazine.com/gnxp/?s=heritability

    my regular readers are totally aware of heritability, though transients may not be.

    if you are the todd at cal i’m a little shocked that you make such gross generalizations which dismiss non-genetic fields of biology. i dig genetics too, but that’s no reason to dismiss biochemistry (god knows biochemists stupidly dismiss genetics enough that there’s no point in aping their worst tendencies).

  • Emma

    “but the empirical reality is a lot of people are putting their hope in GWAS less for finding large effect alleles, and more for possible pathways to target with biomedical research. ”

    Thank you for this interesting point. I thought, mistakenly, that the usual absence of large effect genes in GWAS implied that GWAs would have little practical apllications.

  • Todd S

    Mr. Khan

    As a blogger, I know you’re aware that it’s in your best interest to pull in new readers (or “transients” as you call them) and to not call them names. My comments were not intended to patronize but respond to the questions that your readers had about your methodology (i.e. what went into making that graph that you put up?)

    Additionally, I never dismissed non-genetic fields of biology. They can make contributions that genetics cannot and never said they were irrelevent to science and furthering of knowledge, medicine, and similars. What I did say is that the central tenants of biology that are MOST relevant for laypeople in the voting public who read the articles you cite as being misrepresentative are contained withing the discipline of genetics and that from a basic genetics understanding such laypeople are better equipped at not falling prey to such (unintentional) misrepresentations. My logic is simply that any significant shift towards a genetics focus from a gene focus depends on there being an audience for that shift. It’s incredibly difficult to affect change without incentives that are not purely intellectual. Journalism is a capitalistic endeavor despite pure motivations (the same can be said of any field actually) and changes are more often made in order to draw in more readers than make changes out of principle.

    My very best,
    a “transient” :)

  • http://dispatchesfromturtleisland.blogspot.com ohwilleke

    A few of the accounts of pscyhopathy I’ve read, for example, Martha Stout’s “The Sociopath Next Door” (2005), suggest that the typical pattern of inheritance for psychopaths is to have multiple relatives with mental health issues, but not to have any one of them who is necessarily a psychopath.

    Modeling this kind of extreme personality as a single trait, rather than a confluence of traits that are distinctive when all are present, may be problematic.

    In a multi-component model of psychopathy (for sake of argument, lets call it four parts), descendants of someone 1 SD and 2SD on the psychopathy scale are more likely than a one trait model illustrated in the original post would suggest to have some mental health condition (which would require inheritance of just one of the four components) but probably less likely to be true psychopaths themselves because to do that they have all inherit all four components.

    There are also competing conceptions of psychopathy. The NYT account conceptualizes callous-unemotional as a subtype of conduct disorder (the juvenile analog to anti-social personality disorder – a diagnosis that includes but it broader than psychopathy). But, others see the core distinctive symptoms to be lack of empathy/conscience, and charm/deceit – with conduct associated with violent criminality, animal abuse, etc. having its source in a plus factor like genetic impulsivity, substance abuse, or childhood exposure to abuse.

    One thing that is clear is that whether psychopathy and a few other conditions associated with adult propensity of anti-social behavior is hereditary or merely congenital or has an early childhood source, virtually all people who exhibit persistent serious criminal or anti-social behavior as adults did so as children. Some people (indeed most) grow out of that kind of conduct as they get older (particularly those who are characteristically impulsive or get into the kind of “testosterone conduct” that men frequently engage in but women don’t), but almost nobody who isn’t a problem child becomes a problem adult absent a specific cause like the brain injury suffered by Phineas Gage as an adult, or Pick’s disease (an adult onset form of dementia with distinctive behavioral components in addition to memory loss).

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    As a blogger, I know you’re aware that it’s in your best interest to pull in new readers (or “transients” as you call them) and to not call them names. My comments were not intended to patronize but respond to the questions that your readers had about your methodology (i.e. what went into making that graph that you put up?)

    dude, do you have asperger? wut up with a guy who goes to cal your age writing as if they’re an edwardian gentleman? anyway….

    1) new readers are good, all things equal. IOW, i will trade a few high quality readers for many low quality readers. blogging is a sidelight for me, so don’t throw the traffic card my way. frankly dear sir i don’t give a shit – if the comments are informative and interesting

    2) just cuz you read doesn’t mean you should comment. most people don’t have much to say worth hearing

    3) your comment seemed geared to a retard level of understanding of genetics, at least the first part. the second part about incentives is different, and i’m not going to engage it because i take offense at your pedantic and patronizing tone in the first section

  • Todd S

    Mr. Khan:

    You have me confused with somebody else who you seem to think you know. I have never met you and I have no desire to continue this line of communication. Your writing on gnxp.com was a bit more well-formed and less combustible and I hope to read more writing like what is available there, rather than here.

    :)

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    #17, gmail address takes me to your cal page. also, your IP is from east bay. wasn’t too difficult. though i guess you’re not there anymore according to your linkedin.

  • http://genotopia.scienceblog.com Nathaniel Comfort

    Interesting post. You take a complex set of ideas and simplify it–in this case, to a graph uncontaminated by data or dependent-variable units–which is what scientists and good science writers do.

    What I do, as a historian, is take something apparently simple and make it more complicated. I wonder about how your curves, e.g., would be applied in real life. *Specific* couples, *particular* children–individuals, cases, persons, context.

    I’m asking things like:

    -What would your hypothetical psychopathic lovebirds do with that information?

    -How is the transmission of genetic knowledge shaped by the profit motive? Are there ways in which the need to sell a product (newspaper subscriptions, DTC tests) conditions the way medical-genetic knowledge is disseminated? If so, what if anything should we do about it?

    -People have been making claims about the medical and social importance of heredity for a long time now. What are the historical continuities, what are the differences, and how can we use historical context to inform current choices?

    Anyway, thanks for the post–you’re irascible but insightful. We need clear discussions of both the science and its wider context.

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    I wonder about how your curves, e.g., would be applied in real life. *Specific* couples, *particular* children–individuals, cases, persons, context.

    sure. i applied this sort of model with my own daughter. expected values of height and IQ (parent values and heritabilities known, and no much debate over the value for height).

    What would your hypothetical psychopathic lovebirds do with that information?

    from what i recall most psychopaths, i.e., those tested by psychology or diagnosed through neuroscience, don’t exhibit psychopathy in a realized sense. so most of these people are not pathological. but, they would know they’re kids have a much higher than normal chance of pathology. the most extreme case is that you could simply adopt. more realistically, probably look to social (e.g., tight-knight church) and medical (e.g., medications) which might module the odds more in your favor.

    -How is the transmission of genetic knowledge shaped by the profit motive? Are there ways in which the need to sell a product (newspaper subscriptions, DTC tests) conditions the way medical-genetic knowledge is disseminated? If so, what if anything should we do about

    in the medium-term sequencing will be commoditized. it will be the more complex analytics which will be where the $ is. your questions is kind of general here.

    -People have been making claims about the medical and social importance of heredity for a long time now. What are the historical continuities, what are the differences, and how can we use historical context to inform current choices?

    well, common sense and behavior genetics tells us that the current crazy for attachment parenting is a crazy form of social signalling. that’s what heredity tells us IMO.

  • Helga Vierich

    Interesting article. You might be interested in this: among the Kua (foragers in the Kalahari) if a child seems not to have normal degrees of empathy and remorse by their second year, the parents and grandparents discuss this an begin to pay special attention. Any little incidents that occur where the importance of being fair, of sharing, and of not hurting another person, can be emphasized, are seized upon to make it a really big deal for the child. The child is repeatedly jostled out of any narcissistic behaviour, and definitely subjected to a full arsenal of sarcastic and mocking remarks if they show any sign of deliberate cruelty. No physical punishment is used, of course, only verbal cues. It is said that most children are born with human hearts, but once in a while they need to be “made to feel” human.

    I do not know if these observations are helpful to your present thesis in this article. I have only sketchy field notes on this issue as it was not my main emphasis when I was among the Kua. Melvin Konner has written a magnificent book, The Evolution of Childhood, which I highly recommend, if Henry Harpending has not already drawn your attention to it. I do wonder sometimes about the protective intensity we see in American middle class parents today, and whether this delicate approach to nurturing self-esteem above all else might be back-firing. As the saying goes – the ship is very safe and secure in harbour, but that is not what ships are for.

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Gene Expression

This blog is about evolution, genetics, genomics and their interstices. Please beware that comments are aggressively moderated. Uncivil or churlish comments will likely get you banned immediately, so make any contribution count!

About Razib Khan

I have degrees in biology and biochemistry, a passion for genetics, history, and philosophy, and shrimp is my favorite food. In relation to nationality I'm a American Northwesterner, in politics I'm a reactionary, and as for religion I have none (I'm an atheist). If you want to know more, see the links at http://www.razib.com

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