How to get smarter? What the science says
A follow-up to “Fate, Destiny, Predestination“
In my last article, a provocation was followed by a promise. We are, I argued, largely slaves to our genomes. Our intelligence has a ceiling. But I also said there are answers to the riddle of genetic destiny. So: are there? Can you actually boost your IQ? The truthful answers come from research.
First, how genetic is intelligence anyway?
Before asking whether we can change IQ, it’s worth establishing why it’s so hard to do so. The short answer is: genes. A meta-analysis of virtually all twin studies published over the past fifty years — covering over 14.5 million twin pairs — found that across human traits, the average heritability was around 49%, with intelligence among the more heritable domains. This doesn’t mean the environment is irrelevant, but it does mean that a large share of the variation between people’s cognitive abilities is written in their DNA before they draw their first breath.
IQ scores vs. actual intelligence
IQ and intelligence are not quite the same thing. IQ is a score — a number on an arbitrary scale. Intelligence, or what researchers call g, is the underlying mental capacity that IQ tries to measure. This distinction matters enormously, because it is entirely possible to raise someone’s IQ score without touching their actual intelligence. One prominent analysis found that while education boosted scores on certain tests, it showed no effect on g itself when appropriate statistical models were applied — suggesting a decoupling of educational gains from increases in general intellectual capacity. You score better on the test. You are not, in any deep sense, smarter.
But that is not the whole story. Someone who reasons more effectively, knows more, reads better and solves a wider range of problems may reasonably be called smarter, even if a particular structural model does not show a change in latent g. And the impression how intelligent a person appears can matter in both personal and professional life. How intelligent a person appears can also matter, influencing how others respond to them and producing real advantages in both personal and professional life.
The education effect: real, but limited
The most robust finding in this space is that staying in school longer correlates with higher IQ scores — roughly one to five points per additional year, according to a meta-analysis of over 600,000 participants. Extra schooling appears to improve tested cognitive abilities, but the extent to which those gains represent changes in general intelligence remains disputed. Whether these gains consistently produce measurable change in actual life outcomes, such as increased adult longevity, dwelling values, or higher social status of the communities people died in, is also uncertain.
What about brain traning?
You have almost certainly seen the adverts. Apps promising to sharpen your mind. Do they work? Kind of — but only in the way that practising a penalty kick makes you better at penalty kicks. A 2024 meta-analysis found small improvements in working memory after cognitive training, but much larger effects appeared when the test used to measure improvement was similar to the training task itself — a classic case of getting better at the exam, not the subject. Crucially, training did not improve fluid intelligence, and gains in working memory did not correspond to changes in fluid intelligence.
The growth mindset myth
Perhaps the most popular idea in education over the past decade is “growth mindset” — the theory that believing your intelligence can change will make it grow. The idea is appealing. It is also largely unsupported. Researchers at the University of Edinburgh tested more than 600 children and found that whether or not children believed basic intellectual ability could be changed had no effect on overcoming difficult challenges. The study, published in the Journal of Experimental Psychology, went further: the sole significant effect found ran in the opposite direction. Children with a growth mindset showed worse, not better, performance on more difficult material.
What did help? Old-fashioned effort. Better textbooks. Systematic study habits. The researchers concluded that improved textbooks and systematic study practices are more effective ways of boosting learning than growth mindset interventions.
Where IQ actually moves: removing the floor
Here is where honesty requires a bit of nuance. None of the above means you are stuck. It means the ceiling is real — but many of us are nowhere near it.
There is clear evidence that nutritional deficiencies and environmental toxins can push you well below it. And removing them produces real gains.
Iodine is the most striking example. An influential meta-analysis estimated that people in moderately and severely iodine-deficient populations scored, on average, 13.5 IQ points lower than those in iodine-sufficient populations. Adding iodine to salt — a pennies-per-person intervention — can prevent much of this loss, especially during pregnancy and early childhood. This is not enhancement. It is prevention and partial restoration.
Lead is another. A long-term New Zealand study found that children whose blood lead levels exceeded 10 micrograms per decilitre at age eleven had IQ scores 4.25 points lower at age thirty-eight than their less-exposed peers, suggesting that some developmental harm may be long-lasting.
The evidence points to another few genuinely useful levers. Sleep deprivation measurably tanks cognitive performance, and consistently getting enough sleep restores it. Severe malnutrition, especially in early childhood, suppresses cognitive development — and addressing it raises measured ability. Chronic stress, depression, and anxiety all impair the working memory and executive function you rely on every day; treating them effectively gives your existing intelligence room to operate. Exercise has small but consistent positive effects on attention and memory.
None of this rewrites your genome. What it does is allow you to function closer to your actual potential, rather than below it.
What about the Flynn effect?
There is one important complication. Across much of the twentieth century, average IQ scores rose substantially from one generation to the next. Researchers call this the Flynn effect. Genes could not have changed that quickly, so something in the environment clearly did.
But the Flynn effect does not prove that an individual adult can deliberately raise their general intelligence. Researchers still debate whether these gains represented increases in g itself or instead resulted from better education and nutrition, greater familiarity with tests, and improvements in particular abilities and abstract problem-solving. More recent evidence also suggests that the rise has slowed, stopped, or even reversed in some countries.
Still, the lesson matters. IQ scores are not fixed across populations. The environment can move them considerably. What remains far less certain is whether a healthy adult can intentionally produce the same kind of broad, lasting change in themselves.
The honest answer
There is no pill, no app, no mindset hack, and no study programme proven to significantly raise your general intelligence. The science is fairly clear on this. What you can do is protect the brain you have, reduce the things that drag its performance down, and use education not to become a different person, but to become a more skilled version of yourself.
The script may be written in your genes. But how well you perform it is still, to a meaningful degree, up to you.
Key sources: Polderman et al. (2015), Nature Genetics; Ritchie & Tucker-Drob (2018), Psychological Science; Ritchie, Bates & Deary (2015), Developmental Psychology; Rodas et al. (2024), Psychonomic Bulletin & Review; Li & Bates (2019), Journal of Experimental Psychology: General; Bleichrodt & Born (1994); Bougma et al. (2013), Nutrients; Lanphear et al. (2005), Environmental Health Perspectives; Reuben et al. (2017), JAMA; Lim & Dinges (2010), Psychological Bulletin; Pietschnig & Voracek (2015), Perspectives on Psychological Science; Bratsberg & Rogeberg (2018), Proceedings of the National Academy of Sciences.