Genetic Screening to Enhance IQ Should Be Embraced

By Julian Savulescu, Monash University | March 27, 2014 8:00 am


A version of this article originally appeared at The Conversation.

There could be a way of predicting – and preventing – which children will go on to have low intelligence, according to the findings of a study researchers at Cardiff University presented on Monday. They discovered that children with two copies of a common gene (Thr92Ala), together with low levels of thyroid hormone are four times more likely to have a low IQ. This combination occurs in about 4% of the UK population.

Importantly, if you had just one of these factors, but not both, there did not appear to be an increased risk of low intelligence. These are early results, but suggest that it might be possible to treat children early with thyroid hormone supplementation to enhance their intelligence. This raises many ethical issues.

IQ and Quality of Life

A common objection is that being smarter does not make your life better. In this study, researchers were concerned with those with an IQ between 70-85. Below 70 is classified as intellectual disability but an IQ of 70 to 75 is similar to mild intellectual disability.

Even for individuals with an IQ between 75 and 90 there are still significant disadvantages. Job opportunities tend to be the least desirable and least financially rewarding, requiring significant oversight. More than half the people with this IQ level fail to reach the minimum recruitment standards for the US military. Individuals with this lower level of intelligence are at significant risk of living in poverty (16%), being a chronic welfare dependent (17%) and dropping out of school (35%) compared to individuals with average intelligence. Studies show that they also face an increased risk of incarceration and being murdered.

Linda Gottfredson, who’s undertaken much of this research, concludes that at the very least, “an IQ of 75 is perhaps the most important threshold in modern life”. So it is clear that those of low-normal intelligence, although not classified as disabled, are significantly disadvantaged.

If we could enhance their intelligence, say with thyroid hormone supplementation, we should.

Ethical Decisions

It is important to recognize that the threshold of “normality” here has no moral significance. The dividing line between the IQ classifications of normal intelligence and intellectual disability at 70 is made statistically. It is a statistical point that around 2% of the population will fall below that level.

But what matters is not where you fall on a statistical curve for something like cognitive function, but how bad it is to be at that point – how does it influence your life satisfaction or your well-being? It is pretty clear that low-normal levels of cognitive function tend to reduce well-being, and so those individuals should be candidates for enhancement.

Another common objection to enhancement is that it would create inequality, allowing the rich to get smarter and pass on these benefits to their children. In this case, however, the interventions I am arguing for would only benefit those with an IQ of 70-85 – so it would in fact reduce inequality. This is a strong argument in their favor.

Nature and Nurture

While medical treatments such as thyroid supplementation are promising, there are other avenues by which we can prevent low intelligence. For example, if those at risk of having a low-normal IQ are identified early, enhanced education or other environmental modifications can be employed.

And there is another way this information could be used. Embryos, in the course of in vitro fertilization, are now routinely genetically tested for major diseases. Soon, whole genome analysis will be so cheap that the full genomes of embryos will be available. Should tests be done for gene variations that could contribute to causing low intelligence? Many genes will be like Thr92Ala – they may not confer risk alone, but in combination with certain environments (in this case low thyroid hormone) they have disadvantageous effects.

In my view, we ought to test embryos for such gene variants. Imagine you are having IVF and produce 10 embryos. They are all clear of major diseases, but one of them has two copies of the Thr92Ala gene. Given that there are nine others that don’t have this potentially disadvantageous trait, why not select one of them? Of course this does not guarantee that the embryo you do choose will have normal intelligence, but based on the information you have, it increases the chances.

A common objection is that we should concentrate not on genetic selection, but environmental improvement. You might say: “If my child is genetically disposed to having low intelligence, I will make sure we correct the thyroid hormone levels.”

But life isn’t this certain or controllable – we can’t guarantee that our attempts to control the environment will be successful. All we can do in life is try to reduce the chances of bad things happening, and increase the chances of good things happening. That includes using genetic information to ensure children have the best shot at a good life.


This article was written with the help of Mikael Dunlop, who was formerly at the University of Oxford’s Uehiro Centre for Practical Bioethics.

The Conversation

This article was originally published on The Conversation. Read the original article.


Image by Stocksnapper / Shutterstock

MORE ABOUT: genetics, intelligence
  • Uncle Al

    Genetic Screening to Enhance IQ Should Be Embraced” It’s been done, and it real world works. The Manhattan Project did not diversity hire. 30% of Nobel Laureates since 1900 are Jewish, their genetic heritage overall comprising 1/521 of humanity.

    Do not save the worst, for the worst are in unlimited supply. Fund the best. When the tide rises, all boats float.

    • Buddy199

      Asians are disproportionately represented in the Ivy Leagues. So we need more Chinese people in the world? How ’bout they just study a lot as kids.

    • facefault

      Yeah, and the Manhattan Project had J. Ernest Wilkins, Sam Massie, Lawrence Knox, William Knox, and Moddie Taylor. Trying to guess how someone will turn out from their ancestry is dumb. Just treat people as individuals.

  • sss45

    Interesting piece. I’ve often thought about the idea that the less intelligent a creature is the greater it’s happiness, in general.

    So despite the issues with poverty low IQ individuals may, on a whole, be happier.

    If we assume this to be true, and I’m not saying it is, what we’re really doing is improving the quality of life for these individual’s caregivers (and society as a whole)

  • Buddy199

    That includes using genetic information to ensure children have the best shot at a good life.

    But isn’t that exactly what parents in India and other countries are doing when they sex select against females?

  • Gene Partlow

    This is an example of a new knowledge tool, like any other. And like all other tools, they can be used as weapons by unscrupulous powers, to oppress and divide us. But this has always been true. Yet we still move forward and deeper in our search for knowledge and wisdom. As we should.

    The whole issue becomes much clearer, much less muddy if we rephrase ‘low intelligence’ as ‘low functioning liver’, ‘low functioning heart’, or any of a multitude of clearly debilitating conditions. Who in their right minds would then say, essentially, “..No! I cannot allow “evil medical science” to fix my embryo or my baby so that he or she may have a better liver or heart. It is just fine and wonderful that my child will live to suffer from a poor liver or heart!”??

    The better question then is, why is it so hard for some people to accept the idea of fixing the very foundations of our mental and emotional beings?

  • Mesmer7

    1. Levothyroxine (the hormone replacement drug) is known to cause asthma. It should be banned. 2. It’s long been known that the IQ test is not a valid measure of intelligence or creativity.

    • pzed

      Mesmer7 (were you a Guild Wars player?), the IQ test is controversial, but it’s not an IQ test’s ability to measure whatever “intelligence” is, but rather it’s ability to correctly predict, on average, a person’s future from a youngish age that makes it important and difficult to discount. If all the test did was claim to predict how smart someone was, nobody would still pay attention to it. Executive function and grit also predict life outcomes, but IQ’s impact can be measured independently of EF and grit.

  • Leah Cannon

    Thr92Ala is not a gene name. It describes a mutation which would change the amino acid threonine to the amino acid alanine at position 92.

  • Icabod

    Let’s call this, oh let’s see, “eugenics” come to mind.

    Shades of the ” The Bell Curve” from 1993. That there is a permanent underclass that education will not raise.

    This also brings to mind the end of “Hitchikkers Guide to the Galaxy” a planet ships off all it’s low class workers and promptly dies out due to a lack of hygiene.

    The issue of course is “Who will be the judge?” Which echoes Social Darwinism.

    • FactsNotFallacies

      Ah yes, the eugenics straw man.

      The anti-science left never gets the difference between *preventing births* of people with certain traits and *changing existing traits* in people who are born. Besides…

      • Icabod

        “changing existing traits” makes a good sound bite. It still means telling someone they cannot have a child. Someone will judge them and finding they have an unwanted trail. Having done hundreds of IQ tests, simple IQ scores are a very bad way to predict how people will do.

        • FactsNotFallacies

          It’s funny to see the alleged “experts” or “MENSA” members come out of the woodwork who claim that IQ is meaningless.

          Have a comment that’s still awaiting approval, but in case that doesn’t get through, I’ll just post this here:

  • Robert Boyett

    So, If we increase the average IQ of the population, won’t that just move the IQ bell curve upwards? Won’t there always be a bottom percentage of the population no matter how much the change the IQ? I guess it would squeeze the curve though.


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