Genetics, IQ and the judicial double standard

By J. DeVoy

Emergent research is raising a serious question about the heritability of IQ, suggesting that most of it is, in fact, genetic.  High IQ is associated with the prevalence of certain SNPs – groupings of nucleotides in an individual’s genetic code – which cannot be caused by normal life functions like exercise, eating a healthy diet, or even studying really hard.  Other studies have shown that in-group IQ remains relatively constant over life, indicating that things like education and reading can’t enhance IQ, but merely reflect one’s innate genetic gifts.

Courts, however, have been facing these realities long before now.  In Atkins v. Virginia, the Supreme Court held that it was unconstitutional to execute someone with a severe mental disability — a condition inherently reflecting low IQ.  Similarly, in Griggs v. Duke Power Co., the Supreme Court banned the power company’s use of IQ tests in assigning employees to certain tasks and positions.  Turning to anecdote, I witnessed a sentencing hearing while volunteering for my home district’s Federal Public Defender where the AFPD asked for leniency because the defendant, pleading guilty to child pornography charges, had a shockingly low IQ (below 80).

IQ is used as a one-way street: It excuse the actions of people who cannot function in society without committing crime and harming others, and that is all.  Pointing out low IQ as a reason for individual failure, though, is career suicide — the concept may as well not even exist in those circumstances.  If IQ shows that someone may be smarter than his or her peers, then IQ is just a “social construct”*, as personal success can only be attributed to that ugly “p” word, “privilege.”

While extreme cases like Atkins may warrant heightened protection of individual rights – it is the death penalty, after all – low IQ, like ugliness, is not a protected condition.  Yet, in cases where defendants are incapable of apprehending the wrong of their actions, and even less likely to learn from them, society’s urge to punish them is almost nil.  For instance, an Italian court reduced the sentence of a man who showed he was genetically prone to crime.  Is this bizarro world?  If violence is genetically innate for someone, it makes sense to detain them even longer, probably even forever. Rehabilitation sure as hell isn’t going to happen.

Inasmuch as it is impossible to change one’s genes, it is impossible to expect these people to change hard-wired genetic traits.  Low IQ is not an excuse for criminal conduct, but instead an excellent predictor of it.

While it would be inhuman to punish the low IQ simply for having low IQ, courts and society need to embrace a consistent approach.  Using IQ as an excuse when convenient, while decrying it as a social ill at all other times, is unworkable.  When IQ is a factor in an individual’s criminal conduct, courts and counsel should realize that the likelihood of rehabilitation generally is low.  Though the defendant may not reoffend, that consideration will arise from how strongly his or her law-abiding habits are ingrained as constant behaviors, something ascertainable only on a case-by-case basis.  This consideration does not make low-IQ individuals bad people, and may even make the incarceration experience more sensitive to their unique situation.  This point cannot be reached, though, until courts acknowledge the immutable, unchangeable nature of IQ, and stop allowing it to exist merely as an excuse for criminal conduct.

*g, the general factor of intelligence, is a composite of all other forms of intelligence and a mathematical construct.

23 Responses to Genetics, IQ and the judicial double standard

  1. blueollie says:

    Two things:

    1. IQ is a one dimensional measure of a multidimensional attribute; mathematically one always loses some information when one does this.

    2. Just because something is inheritable doesn’t mean that genetics are the only factor; one’s genes might provide an upper bound in one’s IQ but gene expression can be caused by environmental factors

    Example: human height limits are determined by genes, but

    According to the latest report, the average height of 17 year-olds for the year 2000 was 170.8 centimeters for males, and 158.1 centimeters for females. The same figures for 1900 were 157.9 and 147 centimeters, which means that in the space of 100 years, the height of Japanese teenage boys has risen by 12.9 centimeters, and of Japanese girls, by 11.1 centimeters. This is a remarkable increase when one considers that the height of Japanese of the Jomon and Yayoi periods increased by only five to eight centimeters over the space of some 10,000 years.

    from here

    • J DeVoy says:

      1) G, the general measure of intelligence, is a composite of all forms of intelligence. While an IQ number is a one-dimensional measure, it’s more holistic than people tend to realize and a does a damn good job capturing someone’s abilities.

      2What you’re proposing regarding height increases is accounted for with IQ by the Flynn Effect – namely that even as scaled IQ remains centered at 100, raw IQ has been increasing from generation to generation. I agree that the upper bounds of IQ are genetic and require environmental factors such as nutrition and stimulation to be reached, but I also believe that the importance of those factors in shaping IQ is oversold.

      What is more important are the consequences of low IQ. After 110 or so, IQ doesn’t matter a whole lot, and success is determined by luck and personality features such as extraversion, etc. Low IQ, however, has been constantly found to be correlated with pathologies like crime and dropping out of high school. The low ceiling on these people’s intelligence is genetic, and it cannot be transcended through wishful thinking.

      • blueollie says:

        Low IQ, while limiting, can be caused by environmental factors (e. g. fetal alcohol syndrome).

        I agree that there ARE genetic differences in intellectual ability; e. g., I’ll never be on the same planet as a Nobel Laureate in physics and that some really don’t have the intellectual potential to succeed in our society.

  2. D says:

    When IQ is a factor in an individual’s criminal conduct, courts and counsel should realize that the likelihood of rehabilitation generally is low.

    I think you’re mis-attributing the underlying basis for punishment at play here. While it may be true that the risk of rehabilitation is low, it’s not at all clear that the theoretical underpinning for our justice system is (or should be) rehabilitation – many would argue that we punish to deter, or that we punish for retribution, or even from a Kantian view that it’s morally necessary to punish.

    Regardless of the underlying theory, though, it is a basic principle of our justice system that we punish less those actors who seem less culpable for their behavior. Unusually low IQ is currently one of those traits that we view as reducing culpability. And to the extent that IQ is indeed heritable, the case for reduced culpability is strengthened: if people with especially low IQs are inherently incapable of adhering to society’s standards of behavior, then it starts to look like we’re punishing them for who they are, thereby undermining another widely-agreed principle of criminal justice.

  3. J DeVoy says:

    It’s not at all clear that the theoretical underpinning for our justice system is (or should be) rehabilitation

    I agree that it shouldn’t be, especially since criminals tend to be people who cannot be rehabilitated (excepting obvious smart people/exceptions like Martha Stewart and the Unabomber). We should be punishing these people.

    Regardless of the underlying theory, though, it is a basic principle of our justice system that we punish less those actors who seem less culpable for their behavior.

    And I agree. You treat a 17-year-old who pisses all over the floor differently than a two-year-old who does the same because of the culpability issue. But I’m not asking for a higher standard of culpability, or that the bar for showing someone’s guilt should be lowered in the event of low IQ (e.g. “ladies and gentlemen of the jury, defendant only scored a 98 on the Stanford-Binet test, I REST MY CASE GUILTY GUILTY GUUUUIIIIILLLLLTYYY!”) It should absolutely be considered in punishment, though, and not used as the basis for leniency.

    Low IQ people are incapable of reasoning and live in a state of pure emotional id, like a real-life Homer Simpson. Ever read youtube comments? If we let them around people again, there’s a high chance they’ll commit a criminal act again, maybe even the same one, because they don’t fully grasp the relationship between conduct and consequences. Similarly, if we’re going to push forward the rehabilitation fairy tale, low IQ people have less reasoning ability, and will not be able to learn they are supposed to learn in prison over a short time period. As the one way they could learn is through rote repetition and forced congruity with structure, that seems to fail as well when the consequences for criminal behavior are reduced to nothing on account of the very factors that led them to criminality!

    So, you’re right, IQ shouldn’t be the basis for culpability. But it should be the basis for punishment, however deservedly, so that we actually accomplish whatever goal our schizophrenic criminal justice/prison system aims to reach.

  4. jesschristensen says:

    Jay — I think you’re argument here lacks an account of history in understanding why we’re loathe to use things like IQ scores as a basis for making generalizations about the abilities of people, their capacity for change or criminality. I’ll address that next.

    But first, I also think you have a false (perhaps contradictory) premise at work here as well. You say:

    If IQ shows that someone may be smarter than his or her peers, then IQ is just a “social construct”*, as personal success can only be attributed to that ugly “p” word, “privilege.”

    But, then you say:

    After 110 or so, IQ doesn’t matter a whole lot, and success is determined by luck and personality features such as extraversion, etc.

    Assuming that it’s true that anything above an IQ score of 110 or so, IQ becomes a relatively insignificant factor in the achievements or choices that people attain or make, then it seems to be quite rational that, in addition to luck and personality, one’s relative position of privilege would be a cause of success, or the perception that someone is “smart.” I disagree that as a culture, we attribute all intelligence to being a “social construct,” as our culture clearly rewards individual effort and ability. In any case, my point is that if the playing field is, as you suggest, essentially level after an IQ score of 110, then a whole variety of factors can impact “smartness” and success, including privilege.

    As for why we are wisely hesitant to make generalizations about the genetic immutability of people who score low on IQ tests, this is because such generalizations in the past have proven to be, well, not so true. For hundreds of years in this country, the “leading scientists” of the time (the best and the brightest, mind you) agreed that Blacks as a race, because of genetics, were inherently inferior, lacking the capacity to learn. We used this “scientific truth” to deny rights and opportunity to Blacks. But, experience has shown that those cutting edge scientists of those days were wrong. Which is the same thing that happened with other racial groups and ethnicities in this country and in others, as well as with women the world over.

    In other words, while we acknowledge that the latest science provides useful and important insight into human abilities, we are wise to be very, very careful about using it as a basis for social policy. As such, the justice system has been rightfully reluctant to embrace such scientific theories as the “criminal gene.”

    As for why our criminal justice system exhibits leniency for those who’s mental and developmental condition clearly limits their ability to have made rational choices about their actions—this is because we seek to punish people for the choices they intentionally make, while providing treatment, or at least different consequences, for those who may not have actually made a choice (instead acting on impulse or from an inability to negotiate their environments).

    People with clear developmental disabilities are treated differently by the justice system because they are different, and their culpability for their crimes is different. But, that doesn’t mean that someone with an IQ of 60 who kills someone is let off the hook. They go to different facilities of incarceration (generally public mental health facilities that still curtail their freedom of movement). So, they do have their liberty taken away. We simply don’t sentence them to the same consequences that we would for someone who–as you point out–has an IQ sufficient to demonstrate that their actions were the result of individual choices.

    I don’t really see how that serves as an injustice to “smart people” or creates a situation where the streets are overrun by developmentally disabled criminals. So, what’s the beef?

    • J DeVoy says:

      1) I don’t think that the two statements are contradictory, although it’s a matter of degree. Sure, the 115 IQ DuPont is going to be more successful than a 140 IQ kid from rural Wyoming, but they’re both going to be more successful than someone of middling or below-average intelligence, which is the main point here. Just as there are points of diminishing returns with exercise and investing strategies, the normal distribution of IQ begins to thin out around 110-115 as you cross into the first SD. Generally, a 125 IQ person will be more successful than a 110 IQ person, but in many careers these people can choose, such as accounting or law, there are factors that may make the 110 IQ person more successful than the 125. Both, however, will be more successful than their lest-gifted counterparts.

      2) Science changes. I’m not excusing past racism, but we only need to think back a few decades to when Newsweek’s cover and scientists heralded the onset of a new global ice age. I think that we do have the best science available now, though, and have a good understanding of the human genome. When this is proven incorrect, and new science passes muster, I’ll readily admit my error in believing the predominantly genetic nature of IQ.

      3) I have no issue with treating people who have developmental disabilities humanely, but there are low-IQ people whose conditions are excused due to low IQ, but while still being above the point of developmental disability. That’s where the argument falls apart, because they do have the cognitive ability to recognize right from wrong (or maybe don’t, but clearly are not disabled), but want to have their inferior intelligence serve as a basis for leniency. It’s foolhardy to do so, as they are the most likely people to re-offend. I believe there’s a drop-off where low-IQ people are repeat offenders because they don’t grasp the consequences of their actions, while the developmentally disabled should be put into other forms of state custody because they have conditions that inhibit their comprehension of the world in general. But for people with generic low IQ, it’s less defensible.

      4) Maybe not “developmentally disabled,” but the streets are increasingly full of low-IQ people, as low IQ parents are likely to have more children than those of average or better intelligence. And, accepting my premises at the beginning of the article as true, they’re more likely to be of low IQ and have a host of other ills – low IQ was recently found to be the second best predictor of heart disease.

  5. wouldeye says:

    I don’t really agree that low IQ people can’t be rehabilitated. Sure, their IQ isn’t going to change, but I have to believe that it’s still possible to lower the probability of a repeat offense through education/therapy/some other means.

    I’ve been told that the European justice system tends to work more through rehabilitation than punishment. Is that correct?

    I mean, if we take punishment out of the equation and supplant it with rehabilitation, we’ve got a good argument for holding onto low-IQ people as long as is deemed necessary.

    I don’t know. I think you’re right that the double standard is ridiculous, but I think that something could be done beyond permanent lock up if one suspects that a repeat offense is possible.

    • J DeVoy says:

      I noted that low IQ people can be rehabilitated through force of habit and ingraining good behaviors into their psyche. Historically, this has been religion’s role, but that seems to have fallen by the wayside. But, the extent to which that’s possible needs to be evaluated on a case-by-case basis.

      As for Europe, you’re right. Michael Moore devoted some time to this in Sicko, and the system is about rehabilitation with short sentences and an emphasis on learning the skills of a productive citizen. However, the nations that indulge in this, like Sweden, etc., are much smaller and more homogenous than the US. Also, they don’t have the pressures that the US has to incarcerate people to hide unemployment and keep nonviolent offenders from committing more crime because of their lack of economic participation.

      Permanent lockup might not be a terrible idea. Assuming that low-IQ people are capable of sufficient self-reflection to change, wouldn’t they have not committed the crime in the first place? It’s costly and a horrible way to waste lives. But, it’s going to be the best option until we get real about what low-IQ people, especially criminals who haven’t had sufficient indocrination against criminal behavior already, are going to be able to figure out without aggressive re-education.

      • Nonymo says:

        this is asinine.

        you propose a huge jump in expenditures based on intelligence, when stupid people are overwhelmingly not criminals.

        wait for the science to catch up with your extraordinarily questionable assumptions. it’s obsequious, unprincipled people like you, who take action based on unsupported assumptions, that get us into messes like the iraq war.

        • Where does he call for “a huge jump in expenditures?” It seems like his point is simple:

          1) Low IQ is used as an excuse for some criminal behavior – and thus as an argument that the criminal should be cut a break.

          2) Low IQ people are less likely to change their behavior, thus less likely to be rehabilitated.

          3) Therefore, it seems upside down for low IQ people to be cut a break while high IQ do not get the same.

          What in the fuck does that have to do with the Iraq war?

          You’re free to disagree with him, but keep that crazy shit in your prozac bottle, ok? (and please look up the definition of big words like “obsequious” before you use them).

          • Nonymo says:

            my point was simple. too bad you can’t understand it, although i suppose that explains why you let this guy post his off-topic tirades on your site

            he calls for a huge jump in expenditures when he calls for “permanent lockup” opf prisoners who are dumb, as measured by his precious iq tests. jail ain’t cheap.

            and embarking on expensive and morally questionable programs before you understand the basis for your claims is exactly what got us into iraq. devoy is, sadly, not the first to propose widespread incarceration or discrimination of people because of scientifically unjustified genetic arguments.

            • J DeVoy says:

              Jail isn’t cheap, but what’s the cost of re-offending, in terms of dollars and other costs? There’s no good solution here, but it seems like detaining people more likely to re-offend is a better use of resources than 1) attempting to rehabilitate them, 2) trying to police them after release, or 3) hoping that they’ll learn from their past mistakes and stop repeating them all on their own. All three generally do not work, just as putting an 8th grader in a room with a calculus textbook and expecting him to do differential equations after a few weeks alone is bound to fail. The current system seems likely to demand more of people than they’re capable of in some circumstances and set them up for failure, which i argue is more cruel than keeping them in jail.

            • Nonymo says:

              our current system is very effective and getting better all the time. crime has fallen gradually for over two decades. proposing that we lock people up permanently for the same crime, just because they’re dumb, doesn’t make sense.

              your post is predicated on an idea of a judicial double standard, but you havent even shown that one exists. you cite some decision in italy as your only support.

              so basically you invented a problem out of whole cloth, then proposed a really stupid and expensive solution to the fictional problem

            • I am not sure why it doesn’t make sense.

              If a person commits a crime, we incarcerate them. If they are really really really fucking stupid, sometimes, we cut them some slack because they are too stupid to have known better.

              However, if we look at incarceration as a means of protecting us from people who do bad things, wouldn’t it make more sense to lock dumb people up for longer?

              Naturally, there are other theories of justification for criminal punishment. There is an element of vengeance in the criminal law — and it would make zero sense to visit greater vengeance upon the stupid. In fact, the stupid are perhaps less morally culpable. Accordingly, treating them worse is not logical if you want vengeance. Another theory is that we need to deter crime. Locking up stupid people for longer won’t achieve that goal. In fact, it might even be counterproductive to lock dipshits up for longer, because that might incentivize smart people to use their brains for criminal purposes.

              Nevertheless, you can’t deny that if the goal is removing recidivists from the street, statistically speaking, it would be smarter to lock up the morons.

              You don’t need to agree with the plan (I don’t), but you can’t knock the logic.

            • A) There’s no reason to be a douchebag.
              B) Mr. DeVoy (like all of the writers on the LS) was not selected because of how much I agree with him. In fact, I frequently disagree with him. However, I believe that alternative voices are important so that the discourse is not just an echo chamber.
              C) You are being a douchebag, see A.

            • Nonymo says:

              i don’t care whether you agree with him, but its funny that youre getting so defensive.

              your first mistake is taking for granted that devoy’s telling the truth about the science. he’s not. for example, he links to some dysgenics thing even though its well established that humans are getting smarter each generation.

              other commenters have laid out the real science so i wont repeat it. but i will repeat what i said earlier: he is inventing a fake problem and proposing a really stupid solution

            • Nonymo says:

              i also note that your response in the other thread above totally ignores his point about “permanent incarceration” based solely on iq tests.
              any sane person could see how ridiculous and extremist that position is.

  6. jesschristensen says:

    Jay–it seems to me that one of the things that’s confusing about this post is that it asks two, perhaps related in some ways, but also distinct questions:

    1. What’s the best or most effective way to incarcerate people who commit crimes? and;

    2. Is there any kind of reliable correlation between IQ and criminal activity?

    As to the first question–well, it’s a good one, and one that many have spent immeasurable amounts of time debating and theorizing about.

    As for the second question… Personally, I’m not willing to make social policy based on the science you’ve pointed to, for all of the reasons I’ve outlined about the certainty of the science. Especially when you’re talking about it in terms of the permanent deprivation of the personal liberty of American citizens, based upon an IQ score. It is, without reservation, a draconian proposal, and one that offends pretty basic principles of our society. Your arguments here are simply unpersuasive that anything other than system-wide injustice will result.

    On the other hand, to the very narrow question of: does our current system of criminal justice effectively address the underlying cognitive limitations that many criminals suffer? I agree, it does not. But, I don’t necessarily agree that that’s a genetic problem, so much as an educational one (education in the sense of the development of critical thinking skills, anticipatory decision making skills, etc.) You’re right, you can’t expect a student to learn math simply by being in a room with a math book, any more than you can expect anyone to learn better decision making skills simply by being incarcerated. But, that fact does not in any way argue for the indiscriminate permanent incarceration of people for no reason other than that they score below a certain number on the scientific IQ test of the day. It argues for a better approach to rehabilitative justice than the one we currently have.

    In any case, in my opinion, the entire discussion is pretty useless absent some meaningful definition of what “low-IQ” means, how its assessed, what’s excluded or excepted, etc., etc., etc.

    • J DeVoy says:

      Especially when you’re talking about it in terms of the permanent deprivation of the personal liberty of American citizens, based upon an IQ score.
      I agree and have specifically advocated a case-by-case evaluation depending on how well someone can change their behavior. For some, positive behaviors can be easily learned, and their reintegration to society can be successful. For others, it’s less likely, and it is a danger to re-introduce them to society at an arbitrary point set by the legislature, despite the still-high likelihood of re-offending. IQ is a predictor, and I think it can be a good one when used properly, but it is not a bright line test.

      But, I don’t necessarily agree that that’s a genetic problem, so much as an educational one.
      I kind of agree here. There are methods that can be used to teach anyone; unfortunately, they are not being widely implemented in primary education anymore. Rote indoctrination of an ethic that you need to play by the rules and stay on the straight and narrow, at the expense of being a unique flower, seems to have been traded in for self-esteem training — or so I hear from people who have left the education field in frustration. I think the form of education I advocated could be effective, and would be more potent if it was ingrained from birth, rather than something we need to consider as a dimension of incarceration.

      the entire discussion is pretty useless absent some meaningful definition of what “low-IQ” means, how its assessed, what’s excluded or excepted, etc., etc., etc.
      Partially agreed. I’m just using a binary distinction of low and not-low IQ for this discussion, but what the cutoffs would be, how they’re measured and the number’s predictive value is beyond my area of knowledge. My best guess for information on this would be the research of Linda Gottfredson of the University of Delaware, who has done considerable research on IQ and its relationship with outcomes in education and life.

  7. J DeVoy says:


    The Italian court’s decision is an extension of what we’ve seen in Atkins (admittedly an extreme case, but one fundamentally centered on IQ) and Griggs – people with a predisposition to certain behaviors are given a break that seems counterintuitive. In all other cases, IQ may as well not exist. The fact that high IQ doesn’t even enter the realm of consideration creates the double standard. I understand that you disagree.

    • Nonymo says:

      the fact that you have to go to italy to find a modern case just shoes how far out on a limb youre going.

      your atkins cite is also a stretch. execution of retarded people is very far from permanent incarceration of dumb people. and griggs has nothing to do with criminal law.

      the reason you cant find actual support for the idea that dumb people are advantaged is because it’s simply untrue. defense lawyers may ask for leniency for the dumb, but they also ask for leniency for smart people because they have “potential.” lawyers always try to get a break for their clients but that doesn’t mean theres some sort of systemic problem, which is why you cant find a single relevant example.

      another lie is your dysgenics nonsense. if youve read anything about iq then you know iq has been rising for generations. just like if youve read anything about crime you know crime rates have been falling for generations.

      in other words your extremist solution is in response to a problem that isnt even real.

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