How much sway do our genes really hold over our IQ?

by Sally Blundell / 29 July, 2016
New research explores what influences our intelligence and how we can give ourselves an upgrade.
Photo/Getty Images
Photo/Getty Images


Joseph Flynn was not an educated man. Born in Missouri in 1885, he left school after seven years to work, as his brothers did, in a factory. He was intelligent, says his son, Emeritus Professor of Political Studies at the University of Otago Jim Flynn, an avid reader “genetically programmed to be a high achiever”. But as with his brothers, there remained a “mismatch” between his genetic promise and “the kind of education that might have enhanced his life”.

In Does Your Family Make You Smarter?, Jim Flynn, now 82, explores that mismatch. Is our cognitive ability dictated entirely by our genes? Or does our social environment impact on our and our children’s intellectual skills? Where does human autonomy fit in in the genomic age?

Until now, the answer to the first question was a resounding yes. Studies of adopted children and identical twins raised in different environments have been used to support what Flynn describes as “post-twin pessimism”, the idea that intelligence is largely heritable, that any family influence on cognitive abilities peters out as a child approaches maturity, and that the human race cannot increase its intelligence without upgrading the genes that dictate brain efficiency. Although these studies acknowledge that about 20% of variance in IQ, or intelligence quotient, can be explained by “chance” – uncontrollable events such as injury, illness, marriage breakdown, redundancy – their conclusions support the idea we all have a genetically fixed measure of general intelligence, or “g”, impervious to environmental differences. According to this theory, overall IQ gains simply can’t happen.

Read more: Six ways to enhance your kids' cognitive ability

In challenging these findings, Flynn adopted a new methodology. Rather than relying on the costly and time-consuming studies of twins and adopted children, he used age tables from different IQ test manuals to compare the scores of people in their fifties with those of young children. From this data he was able to measure the degree to which family environment and other non-genetic influences affect cognitive ability.

His findings show that no matter what genetic hand we are dealt, our environment – family background, schooling, job, “chance factors” and the decisions we make – can raise or lower intelligence as it is measured by IQ tests.

Jim Flynn: a new methodology. Photo/Alan Dove
Jim Flynn: a new methodology. Photo/Alan Dove

Changing influences


During preschool years, the cognitive quality of the family environment has a large and measurable effect on children. A family life rich in language, conversation, reading and problem-solving will influence the intelligence of children, no matter what their genetic promise. On the other hand, a downgraded family environment can limit a child’s intellectual performance. A bright 10-year-old with siblings of median intelligence will experience on average a five- to 10-point IQ disadvantage compared with a similar child with equally bright brothers and sisters.

After children start school, the influence of teachers and peers also has to be factored in. A child with a lower IQ, even at age 17, can be six to eight points above their “genetic potential” as a result of being raised in a typical family and being given extra tuition through special education.

Across the age spectrum, from two to 18, the mismatch between genetic and family quality is found repeatedly to benefit low performers and penalise high performers, says Flynn. Such influence is most evident in subjects considered the most important for academic achievement: vocabulary, knowledge and comprehension. Although these skills are enhanced by listening to and engaging with conversations in the family home, this effect is not uniform across the IQ spectrum. By the time a child is 17, family and environment’s influence on vocabulary performance on those in the top 5% of IQ scores will be small; for those in the lower ranges of IQ scores, the influence is stronger. Although an enriching family environment and special education can benefit them by about seven IQ points, someone from a seriously deficient home can suffer a nine-point disadvantage – significant enough to limit the choices they make or can make, both at school and after they leave.

In contrast to the skills children copy from their parents, such as vocabulary, parental influence on more “teachable” subjects, such as arithmetic, tends be more short-lived as the school environment takes precedence. Here, genetic promise does come to the fore. Although parents aim to give all children the same quality of environment, even if one child is slightly more gifted than the other, in the classroom those with a natural flair for maths, for example, are nudged into maths clubs whereas those without such an aptitude are not.

As we enter the world of work or tertiary study, family influences are swamped by those of peers, colleagues and workplaces. But the effect of those early years continues. A good performance at school is more likely to pave the way to more intellectually enriching colleagues and work environments. In his 2007 book What is Intelligence?, Flynn describes this “feedback loop” by which a “gene-caused performance advantage causes a more-homework-done environment. The latter magnifies the academic performance advantage, which upgrades the environment further by entry into a top stream, which magnifies the performance advantage once again, which gets access to a good university environment”. Such “individual multipliers”, he writes, can influence us throughout our lives.

A poor performance at school, on the other hand, may result in an ongoing mismatch between someone’s genetic potential and “current environment”, as they are denied more cognitively enriching opportunities and access to more stimulating people.

It’s not forever


But the story doesn’t end here. The idea that early family environment leaves an indelible mark on our intelligence through life “is simply not true”, says Flynn.

His findings show that the potential to change yourself does not stop at the point of maturity. Most of us can choose to upgrade the cognitive stimulation of our immediate environment, be it by joining a book club, going back to university, or shifting to a job that offers more stimulating challenges or workmates (although Flynn points out that some may be hesitant to trade in their spouses for a more stimulating partner). But again the opposite is also true: “People who share a home or workplace with people whose conversation and interests are limited for any length of time risk seeing their IQ enter a sharp decline because of lack of stimulation.”

Of course, there are limits. The basic circuitry of the brain, agrees Flynn, is latent in our genes. “If at 25 I’d become obsessed with music and plunged into the sort of musical environment Mozart enjoyed as a child, I would never have matched Mozart.” But he says that all of us, at any age, can choose to alter our cognitive environment “so that it either transcends or falls short of our place in the genetic hierarchy”.

The brain is like a muscle, says Flynn. And just as our muscles develop in response to the demands made on them, we can upgrade our intelligence throughout our lifetime by demanding more from our cognitive abilities. He points to London taxi drivers, who show a highly developed hippocampus, the section of brain that deals with map reading, “even though they didn’t have to learn to navigate London’s streets until they were adults”.

UC Berkeley professor Arthur Jensen controversially proposed in 1969 that intelligence was genetically determined.
UC Berkeley professor Arthur Jensen controversially proposed in 1969 that intelligence was genetically determined.

The Flynn Effect


Flynn’s exploration of intelligence and IQ is a 16-year diversion. As a moral and political philosopher, he was researching a chapter about racism for a book on humanist ethics in the late 1990s when he stumbled across the findings of educational psychologist Arthur Jensen showing African-Americans on average had lower IQs than white Americans.

This idea of race-based differences in IQ had alarming ramifications. In 1994, Richard J Herrnstein and Charles Murray, authors of The Bell Curve, argued that if achievement differences are genetically determined, government welfare incentives for poor (low-IQ) women to have children and university quotas for African-Americans were counterproductive.

“I thought, ‘If I’m going to discuss the flaws of racial ideology, I have to know whether some of these claims are true,’” says Flynn. “Jensen was not a racist: he believed in treating everyone on their merits as individuals. But if groups have less potential than other groups, you might discriminate against them – for example, in your immigration policy – so it was relevant for me to test his hypotheses.”

To do this, Flynn looked at intelligence tests conducted by the US military on army recruits from 1917. His research showed that African-Americans were actually gaining on white Americans in test results as their education increased. As he delved further into different intelligence tests, he realised that every decade or so, IQ test designers were “re-norming” their tests, so a score of 100 continued to represent the average IQ of a representative population. When Flynn looked at those normative studies in which test-takers completed both the old and the new form of a test, he found that in most cases, the new group of normative test takers scored higher on the old test than the original group of normative test takers.

These advances amounted to a significant three-point IQ gain every 10 years over much the century. In other words, children who score an IQ of 100 against current norms would have scored 91 against norms of 30 years ago and 70 against the norms of 100 years ago. These changes, now known as the Flynn effect, continued into the post-World War II era, with many countries gaining an average of 15 points. In Holland, the average IQ shot up 21 points between 1952 and 1982.

What was going on? As Flynn explains, we’re not evolving that quickly, “and no one has been machine-gunning people with IQs under 100 in each generation”. IQ gains over time, he concluded, had to be environmental.

Getting smarter?


Are we more “intelligent” than our ancestors? Only insofar, Flynn argues, as the proportion of the population with the skills measured by IQ tests is growing thanks to better – and longer – education, better nutrition, smaller families and a world that’s more intellectually stimulating and challenging. “Not only do we stay at school longer, but at school we also learn to think abstractly.”

Whereas our ancestors in 1900 were focused on the concrete objects of the real world, since the Industrial Revolution we’ve had to rely increasingly on abstraction, logic and the hypothetical to engage with the modern world. If asked in what way dogs and rabbits are alike, for example, a New Zealander at the beginning of the 20th century might have said, “You use dogs to hunt rabbits.” Today, wearing what Flynn describes as our “scientific spectacles”, we’re more likely to say that dogs and rabbits are both mammals – the correct answer for an IQ test.

As a result of the changing “habits of mind” demanded by modernity over just a few generations, we’ve learnt to make sense of computer programming, maths, science, the algebraic symbolism of x (as Flynn writes, “No one has ever observed an ‘x’”) and even the non-representational map of the London Underground. Women, for example, have shown higher IQ gains than men, not because of genetic advantage for intelligence but because of extra “mental exercise” over much of the past century as more girls completed school and went on to tertiary education.

Such advances are not consistent across subject areas – for arithmetic and vocabulary questions, IQs have remained virtually flat for decades. But for questions related to similarities, analogies, pattern completion and picture riddles, results have skyrocketed.

Flynn points to Raven’s Progressive Matrices, which were developed in 1936 to measure mastery of abstract concepts, problem-solving abilities and analogies behind or beyond the represented object – skills “that cannot be taught in a mechanical application of a learnt method”. Flynn says Raven’s Matrices serve as a “barometer of the stage of modernity” and it is on this scale that the most advances have been made over the past century.

These gains indicate not so much growing intelligence but the changing demands of Western society. Although a tribesperson from a remote part of the African continent may score badly on this test, says Flynn, that is a reflection not on that person’s intelligence but on the fact that such abstractions are not relevant to his or her society.

This is the gist of what Flynn and US economist William Dickens describe as the “social multiplier” effect – the role of culture in influencing what particular forms of intelligence society nurtures and rewards. Breakdancing is a common analogy. People skilled in basketball or running may also be good at breakdancing, but if society suddenly decided to upgrade the importance of breakdancing – making it an Olympic sport, for example – more money would be spent on improving our windmill and headstand skills, schools would run local breakdancing competitions and aspiring breakdancers would have to learn increasingly complex moves to stay competitive. Within a generation, the average standard of breakdancing would be greatly increased.

There is a more pressing application of Flynn’s findings. Under capital punishment regulations in many states in the US, if a person has an IQ of 70 or below, they will not be executed on the grounds of intellectual disability. But if a person with an IQ low enough to avoid the death penalty is tested using obsolete norms, the same performance may give a higher score – enough to send them to the execution room. Flynn has spent the past decade, with some success, educating judges on these ramifications and urging the re-standardisation of tests every generation or so.

New Zealand instituted what is thought to be the first nationwide use of intelligence testing in the 1920s at the recommendation of Waitaki Boys’ High School rector Frank Milner when he returned from a study tour of the US. Photo/Alexander Turnbull Library/4-020167-F
New Zealand instituted what is thought to be the first nationwide use of intelligence testing in the 1920s at the recommendation of Waitaki Boys’ High School rector Frank Milner when he returned from a study tour of the US. Photo/Alexander Turnbull Library/4-020167-F

Testing, testing


Flynn’s research on IQ has been quoted worldwide; London’s Times called him “one of the greatest scientific thinkers of our time”. And it prompts a re-evaluation of how we define intelligence. The first IQ tests, he writes, were designed by scholars to measure the conceptual skills needed for cognitively demanding jobs or formal schooling. These date back to the beginning of the last century, when the French Government asked psychologist Alfred Binet to find a way to identify students mostly likely to experience difficulty at school. Binet and his colleague Theodore Simon compiled a questionnaire related to skills not taught at school, such as attention, memory and problem-solving abilities.

Although Binet recognised the limitations of a single, supposedly inborn measure of intelligence, from 1916 the new Stanford-Binet Intelligence Scale, adapted by Stanford University psychologist Lewis Terman and revised four times since then, quickly became the standard intelligence test used in the US to diagnose intellectual deficiencies in young children. (Following a US study tour by Waitaki Boys’ High School rector Frank Milner in 1924, New Zealand’s Education Department began applying the Terman Group Test of Mental Ability to all first-year post-primary school students in what is thought to be the first nationwide use of intelligence testing anywhere in the world. It was later replaced by the Otis Intermediate Intelligence Test, which remained in use until the late 1960s.)

Based on knowledge, quantitative reasoning, visual-spatial processing, memory and “fluid reasoning”, the Stanford-Binet test presents a single IQ score by dividing a child’s mental age by his or her chronological age, then multiplying this number by 100. So a child with a mental age of 12 and a chronological age of 10 would have an IQ of 120.

A number of different tests have been designed since then, including Raven’s Matrices and, in 1955, the Wechsler Adult Intelligence Scale (WAIS), now in its fourth revision. Such measures of IQ are still in use, but our understanding of intelligence continues to evolve. In Does Your Family Make You Smarter?, Flynn presents his new “meta-theory of intelligence”: a combination of mental acuity (the ability to solve on-the-spot problems never encountered before); habits of mind (the extent to which people use logic and symbols detached from the concrete world to analyse problems); vocabulary; knowledge and information; speed of information processing; rote memory; and working memory. In summary, he says, intelligence is “the brain’s capacity to use memory and learning to adapt to the world as we have made it”.

Capitalising on our gains


Now, however, Flynn expects that the cognitive gains made over the past century, in more developed countries at least, will slow. “Formal education has exhausted its bags of tricks to upgrade logical analysis of abstractions; we already have about as small families as we can; people’s leisure time is now being downgraded. We have as many professional jobs as we can have – we already feather-bed them to an extraordinary degree – and the modern creation of jobs is tending towards service jobs, so challenging jobs are being limited. So all the triggers that have prompted IQ gains are running out of steam.”

He says the challenge now is to capitalise on the gains we have made. And capitalise we should. High IQ as a measurement of cognitive ability equates with good health outcomes and longevity; parallels and predicts growth in GDP per capita; and is also an ongoing promise for a new generation having to confront and address the ramifications of a rapidly changing job market and the challenge of climate change (Flynn’s book on climate change will be published later this year by Potton & Burton).

Like Harvard University psychologist Steven Pinker (who provides a glowing review of this book), Flynn has no time for those who say human nature is a blank slate that environment may do with as it may, but he refuses to believe that the findings of twin studies, for example, should act “as a genetic veto on our sense of social justice and our efforts to improve our children, ourselves and our species”.

Does Your Family Make You Smarter? Nature, Nurture, and Human Autonomy, by James Flynn (Cambridge University Press, $36)

Read more: Six ways to enhance your kids' cognitive ability

Joseph Flynn.
Joseph Flynn.

The rich world of reading


Though he had little formal education, Jim Flynn’s father, Joseph, loved to read. “And read aloud,” recalls his son. “When I was four, he read me all of Dickens – that opened up a whole world.” Now, every year, Jim Flynn walks across town to Dunedin’s Columba College to present the awards to students who have worked their way through five books from Flynn’s The Torchlight List, the soon-to-be updated inventory of 200 books that he believes will encourage people of any age to make reading a habit (the list takes its name from Flynn’s “uneducated” seaman uncle, who read by torchlight aboard ship during World War I).

A high level of literacy is important for future employment, Flynn says, because those with poor reading and writing ability don’t prosper in the job market. A 2006 report by the New Zealand Council for Educational Research (NZCER) says that by the time a child turns 14, enjoyment of reading is a key indicator for engagement in learning and competency levels. Students who enjoyed reading were found to have consistently higher scores for mathematics, reading and the composite score for attitudinal competencies than those who did not. Students who lacked interest in reading at 14 were more likely to have lower language skills and were less likely to complete their homework and be enthusiastic about going to school.

Flynn says reading is also important for children to become “truly autonomous human beings. As children spend more time on visual media, they lose the whole rich world of literature that tells you about other people and about history. So we have all these kids with high IQs and we can’t capitalise on it. And if they don’t read any history, you can lead them to Iraq and a stupid war that anyone would avoid if they knew something about the history of the Middle East.”

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