There is no intelligence gene... singular

IQ is genetically inherited. It’s best for children—and parents—that we admit it

March 16, 2016
A display representing a DNA sequence at the Science Museum, London. ©John Goode
A display representing a DNA sequence at the Science Museum, London. ©John Goode
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Psychologist Oliver James’s claim, in his new book Not In Your Genes, that personality traits such as intelligence are not genetically inherited has been widely and rightly denounced by scientists. It is flatly contradicted by an abundance of hard data, which shows for example that IQ may have as much as 80% of an inherited component. To suggest otherwise amounts to scientific denialism.

James has said the turning point came when he read a comment in 2014 from Robert Plomin, a behavioural geneticist at King's College London and a leading expert in the genetic aspects of intelligence, saying that after searching for 15 years for genes relating to inheritance, "I don’t have any." Many candidate genes have been mooted, only for the evidence of an effect to evaporate when larger samples are analysed. Later in 2014 Plomin was part of an international team that identified three genes with an apparently robust link to IQ—but collectively they seemed able to account for just 1.8 IQ points.

Why, when heritability studies show so clearly that IQ (whatever that measures) must be partly "in our genes," it is so hard to figure out which genes is still a mystery. No one expects a trait as complex as intelligence to be governed by just one or a few genes; some estimates put the figure as something more like hundreds, perhaps even thousands. On the one hand this makes it less surprising that pinning effects to specific genes is so hard. On the other hand it raises the question of exactly what it could mean to say that these genes are "for" intelligence. Most if not all would almost certainly have biochemical roles some distance removed from anything easily connected to brainpower, and which probably serve other essential functions too (which is why talk of editing the human genome to breed super-intelligence seems fanciful).

This difficulty of linking the direct roles of genes to the phenotype (traits) of an organism is a general challenge for modern genetics, affecting in particular efforts to identify the genetic origins of inherited diseases. Some think it will require new ideas about how the genome functions at a level higher than the activity of individual genes. But in some ways it goes also to the heart of the controversy about James's book.

Most of the responses to his misinformation have stopped at the stage of pointing it out. This needed to be done. Yet there seems to be a widespread distrust, among thoughtful people, of attempts to tease out the genetic contributions to intelligence. For example, writer Michael Rosen, a former Children's Laureate, has expressed vehement disapproval. One might fairly say that the battle lines are loosely drawn between geneticists on one side and psychologists and educationalists (Rosen has had lifelong involvement in children's education and literacy) on the other. The distaste for suggestions that genetics affect intelligence seems visceral, despite the evidence—so it's worth considering why that is.

I have yet to come across a teacher or educationalist who really feels that children are blank slates, devoid of all innate (including inherited) differences in their capacity to achieve certain tasks. So why the unease about linking these to genes? The reason, I think, stems from a perception that admitting intelligence might be even partly in the genes would be to consign children to a deterministic judgement: there's no point trying to help them, because they are fundamentally limited by their DNA.

The irony is that researchers like Plomin are motivated by quite the opposite view: they hope that an understanding of the genetic dimensions of intelligence would actually improve education, perhaps especially for those at an inherited cognitive disadvantage. There seems, for example, to be to be a genetic component to dyslexia. If this could be reliably diagnosed from a child’s genome sequence, that might save the child from being labelled slow, inattentive or other traditional blanket terms for "poor achievers," and would let them get the help they need without delay and detriment to general learning. Plomin wants to see education tailored to genetic predispositions, especially for pupils who struggle.

This is a laudable goal, although it looks at best a distant prospect given the difficulties encountered so far in finding specific genes associated with educational outcomes. What seems to upset some educators, though, is that this threatens to make education a mechanical process that ignores the wealth of experience already acquired in helping "low achievers" to thrive, without having to assign them some gene-based label—and perhaps to medicalise issues that might be better addressed by thoughtful teaching interventions that take the child’s circumstances into account. In this way, mightn’t a gene-centric view only promote the reduction of education to a set of narrowly defined performance skills and instrumentalised metrics, towards the attainment of which all hurdles must be removed?

The two views—recognizing the role of genes in cognition, but nurturing diverse talents through sensitive and intelligent teaching—aren't necessarily incompatible. But there seems to be sadly little dialogue between them, as James's book attests. It's easy to show that James's position is contradicted by the evidence, but I suspect his denialism is motivated in part by a discomfort with what genetic studies could seem to be aiming at: a replacement of psychological or social perspectives on character and development with analyses of DNA. Perhaps we might then end up focusing on the issues that science can quantify, rather than the ones we should be most urgently trying to address. Many educationalists would argue that some of the most critical problems today aren't those relating to genetic limitations on cognition, but to environmental factors—at home and at school—that disrupt a pupil’s ability to learn.

These, after all, are things we can potentially address today, rather than when at some future stage we might have finally identified genes (if they exist), or at least particular genetic profiles, that have a strong impact on IQ. Again those aren't mutually exclusive goals, but one has to wonder if some geneticists consider the former to be worth attending to at all. When I suggested in 2014 that there did not seem to be any reason to suspect genetic factors as a key influence in the socioeconomic disparities of educational achievement, Plomin responded by turning this into an issue of whether there is any genetic influence on intelligence at all (which there clearly is). When I asked him to clarify whether he believes that genetics lies at the root of the lower average educational attainment of economically disadvantaged children, he did not reply. Similar smokescreens were thrown up by other proponents of a focus on genetics in education—for example, they pointed out that the degree to which genetic factors are modulated by socioeconomic disadvantage is not clear, or that on a level playing field genetic influences would become even more paramount. These statements were correct; they also distracted from the issue to a degree that seemed almost calculated. That kind of evasion only feeds the unease of folk who fear that admitting to the genetic influence on intelligence will reduce education to a matter of cultivating a cognitive capacity to jump through hoops.

It’s hard not to sense glee in some suggestions that genetic factors overwhelm any efforts a parent or teacher might make to assist education, or indeed to intervene in most aspects of personality. “Look at you with your middle-class intensive parenting, and it’ll make not a blind bit of difference!” Yet there is abundant evident evidence from research in child development and psychology that influences during childhood (including trauma, but also more subtle factors such as parenting and teaching styles) can and do have a huge impact on capacity to learn, to relate, to find emotional well-being and stability.

The emphasis on genes might be partly a backlash against a perceived over-readiness today to indulge the individuality and feelings of the child at the cost of basic skills and standards of behaviour. But to imply that environment is likely to play only a minor role in general emotional and intellectual health and well-being is itself a kind of denialism too—not just of science but of responsibility. It is the other side of the coin to what Deborah Orr has identified as the real danger of James's position: that it could make parents feel responsible for personality disorders that are inherited.

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