not all in the genes

Dominic Cummings’ 2013 essay Some Thoughts on Education and Political Priorities reveals his keen interest in the implications of intelligence research for education. His Endnote “Intelligence, IQ, genetics, and extreme abilities” (p.194) runs to 17 pages.

General Intelligence

If I’ve understood Cummings’ model of intelligence correctly, it goes like this: General Intelligence (‘g’) is a trait that’s largely genetically determined and can be measured as IQ. If we could identify the genes involved, we could spot those with high cognitive ability who are needed to find the solutions to the complex problems facing us.

There’s certainly robust evidence that cognitive ability is largely genetically determined (by multiple genes), remains stable, and is a good predictor of lifetime achievement (p.197). We do need people with high IQs to work on solutions to world problems. And children with high IQs need an appropriate education. I share Cummings’ frustration that DfE officials prioritised their notion of equality over the need to develop talent (p.64). But his model is also flawed at several levels. It includes three key components that are worth examining in more detail;

  • A hypothetical human trait – general intelligence
  • The correlation between factors within intelligence tests
  • IQ


Towards the end of the 19th century, researchers got very interested in measuring human characteristics. Some, such as height and weight, were easy to measure, but others – like ‘physiognomy’ or ‘eventuality’- were trickier because it wasn’t obvious what the features of ‘physiognomy’ or ‘eventuality’ were.


You can of course measure any human characteristic you fancy. You decide what the features of ‘adhesiveness’ or ‘ideality’ are and how to measure them, and hey presto! you’ve measured ‘adhesiveness’ or ‘ideality’. There might of course be some disagreement about the features of ‘adhesiveness’ or ‘ideality’ – or even about their very existence.

Also in the late 19th century, industrialised economies were desperate for a literate, numerate, ‘intelligent’ workforce. That requirement was one of the drivers for mass education.

In his 1904 review of measures of intellectual ability, the psychologist and statistician Charles Spearman decided intellectual ability could be measured using performance in: Classics, Common Sense, Pitch Discrimination, French, Cleverness, English, Mathematics, Pitch Discrimination among the uncultured, Music, Light Discrimination and Weight Discrimination (Spearman p.276). Essentially, he defined intelligence in terms of intellectual abilities. More recent measures such as Verbal Comprehension, Visual Spatial, Fluid Reasoning, Working Memory, and Processing Speed (Wechsler Intelligence Scale for Children – V) define intelligence in terms of cognitive abilities.


Spearman went a step further. The positive correlations between the factors in his test convinced him “that there really exists a something that we may provisionally term ‘General Sensory Discrimination’ and similarly a ‘General Intelligence’” (Spearman p.272). And the correlations between scores in cognitive ability tests have convinced others of the existence of a ‘something’ we may provisionally term ‘general intelligence’.

I haven’t been able to find out if Spearman used ‘g’ to refer to the correlation between factors, or the hypothesized ‘something’, or both. Whichever it was, critics were quick to point out that correlation doesn’t indicate causality. A positive correlation between Spearman’s factors exists, certainly. Whether ‘general intelligence’ exists other than as a folk concept is another matter.

Critics also pointed out the circularity in Spearman’s argument. Intelligence tests were assumed to measure intelligence, but because no one knew what intelligence actually was, the tests also defined intelligence – even if they varied considerably. Spearman’s measures were very different to Binet & Simon’s , and neither bears much resemblance to the WISC, or to Raven’s Progressive Matrices. As Edwin Boring put it in 1923, “intelligence is what the tests test”.


In 1912, the German psychologist William Stern developed the concept of IQ –Intelligenzquotient. IQ (initially mental age divided by chronological age, expressed as a percentage) tells you how an individual’s test score compares to the average for the population. But the criticisms of ‘intelligence’ also apply to IQ. IQ tests undoubtedly measure aspects of cognitive ability, but we don’t know whether or not they measure a genetically determined trait we may call ‘intelligence’. Or even if such a trait exists.

Advocates for general intelligence haven’t take the criticisms lying down. Cummings quotes Robert Plomin’s dismissal of the circularity criticism: “…laypeople often read in the popular press that the assessment of intelligence is circular – intelligence is what intelligence tests assess. On the contrary, g is one of the most reliable and valid measures in the behavioral domain” (p.195).

It’s worth noting that Plomin uses g and intelligence interchangeably, even though intelligence is a hypothesized trait and he refers to g as a measure. There’s no doubt that g is reliable and valid when measuring some cognitive abilities. Whether those abilities represent a genetically determined trait we may term ‘intelligence’ is another matter – which Plomin goes on to admit: “It is less clear what g is and whether g is due to a single general process, such as executive function or speed of information processing, or whether it represents a concatenation of more specific cognitive processes…” It’s also worth noting that Plomin attributes the circularity argument to laypeople and the popular press, rather than to generations of doubting academic critics.

The implicit assumptions made by those emphasizing the importance of g and IQ, are important because they can have unwanted and unintended outcomes. One is that correlations between factors might hold true at population level, but not always at the individual level. Deidre Lovecky, who runs a resource centre in Providence Rhode Island for gifted children with learning difficulties, reports in her book Different Minds having to pick ‘n’ mix sub-tests from different assessment instruments because individual children were scoring at ceiling on some sub-tests and at floor on others. How intelligent are those children? Their IQ scores wouldn’t tell us.

Also, hunting for hypothetical snarks can waste a huge amount of time and resource. It’s taken over a century for us not to be able to find out what ‘g’ is. Given the number of genes involved ,you’d think by now people would have abandoned the search for a single causal factor. It’s a similar story for chronic fatigue syndrome (‘neurasthenia’ – 1869) and autism (‘autistic disturbances of affective contact’ – 1943); both perfectly respectable descriptive labels, but costly red herrings for researchers looking for a single cause.

Characteristics, traits, states, and behaviours

What convinces Cummings that intelligence, g and IQ are ‘somethings’ that really exist is evidence from behavioural genetics. Scientists working in this field have established beyond reasonable doubt that most of the variance in human intelligence, however you measure it, is accounted for by genetic factors. That shouldn’t be surprising. Intelligence is almost invariably defined in terms of cognitive ability, and cognitive ability emerges from characteristics such as visual and auditory discrimination, reaction time, and working memory capacity, all biological mechanisms largely determined by genes.

But not all human characteristics are the same kind of thing. Some characteristics such as height and weight are clearly physical and are easily measured. For obvious reasons genes account for most of the variance in physical characteristics.

The term trait applies to physical characteristics but also to stable dispositional characteristics. Disposition refers to people’s behavioural tendencies – how introvert or extravert they are, what they like and dislike, do and don’t do etc. The evidence from behavioural genetics suggests that genes also account for most of the variance in stable traits.

States are also dispositional characteristics, but they’re temporary and usually emerge in response to environmental factors. So Joan might be extravert and prone to angry outbursts, and Felicity might be introverted and timid, but both of them are likely to become anxious if fire breaks out in the office they share. Their reactions to the fire are largely genetically determined, but are triggered by an environmental event.

Behaviours are things people do. They are undoubtedly influenced by genetic makeup, but occur primarily in response to environmental factors, because that’s the main function of behaviour. Joan might try to extinguish the fire and Felicity might take the nearest exit, but both behaviours would be in response to specific circumstances. If we were pre-programmed automatons, the human race wouldn’t have lasted very long.

In support of his genes-determine-intelligence argument Cummings cites Stephen Hsu, a physicist turned behavioural geneticist, who claims that much of the nature/nurture debate has been settled. Hsu’s right in respect of the genetic influence on traits. But that still leaves plenty of room for the environmental influence on states and behaviours. That has significant implications for Cummings’ model of education.

Genes, intelligence and education

The principal components of Cummings’ model of education are genes, intellectual ability, effective teaching, and exam results. But in real life many other factors impact on educational outcomes. Take Ryan, Joan’s nephew, for example.

Ryan lives with his mum, a single parent. She cares for her father, disabled following a work accident, and her mother who has complex health problems. They live in a former industrial town, currently in economic decline. Ryan’s parents’ relationship broke down due to the financial and time pressures on the family.

Ryan has average intellectual ability, but episodes of glue ear when he was younger left him with a slight speech and language delay. He struggled with maths and reading and was often reprimanded for not following instructions. He loved physical activities, but the regulatory education framework required Ryan, as a child who was ‘falling behind’, to do less practical activity and more arithmetic and phonics.

Ryan soon began to disengage with school. He was referred for speech and language therapy and to the educational psychologist, but both had lengthy waiting lists. By his teens, Ryan had a low reading age, was making slow progress academically, and skipped school whenever he could. His mum couldn’t find paid work to fit around caring for her parents, and was on medication for anxiety and depression.

Genes undoubtedly account for some challenges faced by Ryan and his family; his family’s health, his intellectual ability, and quite likely his glue ear. But environment plays a significant role in the shape of income, diet, viral infections, and national economic, social, and education policy. So do life events (so commonplace their importance is often overlooked); where the family happens to live, grandfather’s accident, parents’ break-up, which school is closest to home.

Then there are specific behaviours on the part of Ryan, his parents, grandparents, teachers – and government ministers. Specific behaviours are often framed as a ‘choice’, but that choice is often highly constrained by circumstances.

Choose your metrics

Cummings measures the effectiveness of the education system by exam results (although he questions the quality of the exams). Exam results are positively correlated with IQ, and IQ is largely genetically determined. So his choice of metric means Cummings places a disproportionate emphasis on influence of genes on educational outcomes.

Of course there’s nothing wrong with IQ or exam results as metrics. If you want to find someone with good cognitive abilities, a modern intelligence test can identify them. If you want candidates with a mathematical ability of at least GCSE level, check out GCSE maths results.

But the choice of a single metric for something as complex as an education system shows an inadequate understanding of complex systems. And begs the question of what education is about. If quality of life in local communities were the key metric, the education system would look very different. By bizarre coincidence, the gene pool of large populations produces people with a wide range of abilities and aptitudes, just what those populations need in order to thrive. That wide range of abilities and aptitudes should be cultivated. Cummings’ choice of metric means the exam-results tail wagging the quality-of-life dog.

Accommodating a wide range of abilities and aptitudes doesn’t equate to having ‘low expectations’ for those with less than stellar exam results. There’s no virtue in people doing jobs they don’t enjoy and aren’t good at, and careers aren’t set in stone. An academic high flyer might become a superb potter, and a former train driver might get a PhD. If the education system doesn’t offer such opportunities, it’s to the detriment of all us.

Cummings would no doubt argue that his claims about education are evidence-based; he cites evidence for pedagogical approaches that improve exam results. But his starting point is an assumption that what the world needs is academic high flyers with high IQs and ‘extreme abilities’. He looks right past those with other abilities and aptitudes essential for communities to keep functioning. And those, who through no fault of their own, can make only a very limited contribution to their communities, but like all of us have a right to a decent quality of life.

Cummings first chooses his metric and then chooses supporting evidence, but only the evidence in support of it. Ironically history is littered with examples of academic high flyers with high IQs and ‘extreme abilities’ causing chaos for the rest of us. Cummings’ use of evidence is the subject of the next post.


Spearman, C.  (1904).  ‘General Intelligence’ objectively determined and measured.  The American Journal of Psychology, 15, 201-292.


Image from People’s Cyclopedia of Universal Knowledge (1883) via Wikipedia



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