Blog Essay: Is IQ Purely Genetic?

The Dodgy IQ Game 

Disclaimer: I usually write pretty casually here, but sometimes when something really gets my goat, I'll childishly pop out references just to make a strong point. This is one of those posts! 

The Genetic Foundation of Intelligence

Someone I know has a thing for IQ. The idea of passing Mensa to be in the top 2% of the population was their absolute dream! In fact, after splashing out on a test, and then, one day saying, 'IQ is capped by racial genetics,' another disagreement began. Okay, I thought, yeah, people wouldn't exist, let alone think, without their genes, but I can't agree with our general intelligence having a prescribed ceiling height; I had to look into this stuff.

Let’s Start With Genes

Of course, genetics may well be our prime disposition for things, but how we nurture cognitive ability will always play a role in its development into real intelligence. So I've been looking up some meaty stuff and decided to have a crack at making this a tad more academically flavoured:

Genetics tells us our FOXP2 genes play a vital part in complex communication (Becker et al, 2018). We humans are rich with the gene, like bats, whales, dolphins but we regulate it especially for our complex speech and language - that's why you can read this post. A mutation or lack of FOXP2 is often linked to speech and language disorder. But, whenever people try new methods to overcome their disabling comminication problems that's also intelligence in action. This means intelligence goes deeper than just IQ.

The genetic contribution of our individual differences, or heritability makes perfect sense; it stands up to pro G factor arguments (the idea of intelligence being capped by IQ results). Sources like Plomin et al. (2016) say 50-80% of IQ variation come down to genetics. In other words, if height is about 80% heritable, but our average height has dramatically increased over many generations, is that ALL genetics? No. It's just better nutrition! The genes didn't change - the environment did. Narcissistic types will use IQ with a kind of reductive talk to distinguish themselves from others. My other blog here, explores how IQ test scores can brand people of faith. Should we be saying Christians are cognitively inferior to the Atheist because their IQ scores show a trend? We have to understand the figures. 

Questions of Validity

For now let's consider adoptive children and also fraternal twins. Some twin studies are particularly useful at showing how identical twins raised apart have strikingly similar IQs, but many show differences (Plomin et al. 2016). 

If I can play devil's advocate here by asking you to imagine one of those twins had a predisposition for bipolar disorder. Would a depressive episode during an IQ test be an environmental or genetic factor if the score is, say, too low? Bipolar states can easily disrupt our mental functioning in an IQ examination. No doubt, OCD has stolen test time with compulsions to overly re-check everything; need-based test tweaking is another component supporting an unsure result. It allows margin for error and room for doubt. About 1 in 4 US and UK citizens had mental health issues in both 2022 and 2024. This rough figure is static, remaining in the same ballpark as the Time to Change campaign which ended in 2021. This is around a quarter of the population who would be misrepresented in a standard IQ test. Have you ever seen an IQ test that offers a notch for notch handicap following a conditions individual severity? Psychiatrists don't detail the cognitive impairment of their individual outpatients; quality of life is the focus—it's poorly tracked. 

On the same note, the genetic architecture of autism with its neuronal clusters, can actually reveal a much clearer gap between IQ and adaptive functioning or common intelligence. Studies followed high functioning autistic boys and scored them as average to above average, they did better than autistic girls. Of course, limited education, black and white thinking, oppositional defiance, and rigidity of thought are not helpful with flowering a developing mind with enough intelligence to navigate life with the same ease as neurotypicals—spikes or splinter skills are frequent in neurodivergence. 

IQ testing has clearly not considered everyone's intelligence adequately. 

Do fainting goats faint because of a genetic mutation, or is it because of the loud noise that startled them?

Education

The claim of high IQ is the prime cause of success is questionable. A 20 year study of doctors in the United Kingdom confirmed A-level grades are much better at predicting professional success than IQ scores. The study categorically showed IQ measuring ability (potential) and A-levels measuring achievement (application and knowledge). Impressive A-levels served better as the applied discipline needed for career longevity. The AH5 IQ test, was more suitable for this study than regular Mensa testing as it is more rigorous than entry level confirmation.

Significant effort from a student with average-IQ often beats low effort from a student with a high-IQ.

That Bell Curve of the 90s

This is the crux of it. The need to feel superior over other ethnicities has resulted with studies like Herrnstein and Murray's The Bell Curve (1994) being celebrated. It promotes racial IQ differences mostly based on numeric data that meets their need. 

Figures like the philosopher, Ned Block have criticised Herrnstein and Murray for oversimplifying intelligence and ignoring cultural bias in testing. Cold numbers alone are ignorant. Nisbett et al. (2012) argue that socioeconomic factors and historical inequality play a big role. Depending on place, time, candidate and tester, examinations can still be ill suited. 

Before the Berlin Wall fell, why was there a consistent difference in IQ between East and West Germany of 5-10? It was not the Germanic 'race' but, obviously the inequality in socioeconomic standards. The scores eventually equalised as their economy did. We see the same in this classic controversial longitudinal adoption study. Black children raised by more fortunate non-black parents increased their IQ scores.

Yes, we know East Asian countries dominate the top IQ rankings; Japan and Taiwan are tied for first place, but they regularly push IQ tests in their educational practices. 

Neuronal and Social Clusters  

We have to be honest and accept there are genetic conditions specific to certain ethnicities. This proves genetic variation exists across populations, but that is illness and not racial intelligence. Can you think of any genetic conditions linked to higher IQ prevalence? Again, we have to say yes, neurodiversity, but does that always capture all-round intelligence? No. 

Health-aware and more fortunate families across the west are more likely to see the signs of neurodivergence in their kids and get help, than those with health nihilism. We know many gifted children of this demographic gravitate towards bodies like Mensa. Others do not. The Mensa ADHD rate alone is 7.4% of members (IQ over 130)! All self-reported - that's nearly double the estimated general adult population rate! 

Ethnicity Figures

Regarding ethnicity in the USA: We see a decent amount of Asian or Pacific Islander children have an ASD - prevalence of 38.2 per 1,000 children, many are high functioning. 

White children have more ‘higher-functioning’ ASD with fewer affected with Intellectual Disability (ID). 

Black children have a prevalence of 36.6 per 1,000. Unfortunately, numbers show a comparatively higher count of ID. Frequent misdiagnosis of behavioral disorder is uncovered in the data, and non-diverse evaluation led to fewer HF ASD black children being identified. 

Scarr and Weinberg (1976) argued environmental factors override genetic predispositions, that is to say, intelligence can be wasted or lost in abject poverty or hardship. Cold numbers show IQ averages and who is being diagnosed with what - not the complex factors and social circumstances of life like in the 1980s Germany study. 

Please, explain how racial IQ is benefitting anyone, given we don't fully understand intelligence yet. 

Human brain scan

The Importance of Context: How Environment and Genetics Intersect

We touched on the boundary line separating genetics from environment, it can look quite blurred. For instance, Turkheimer et al. (2003) presented how the influence of genetics on IQ is moderated by such environmental factors. Yes, the paper says a bit about wealthier kids showing a higher heritability of impressive IQ, but instead, it's the impoverished kids from harsh or abusive backgrounds that are an overlooked detail: abuse-based cognitive issues are symptoms not the cause. It stems from the trauma of sensitive and intelligent individuals.

Intelligence from an evolutionary position is also environmental. Living north of Svalbard and The Congo both require types of intelligence not useful in France. We showcase our diverse resourcefulness and adaptive resilience even today. Let's be honest, do you think ancestral tribes of the frosty tundra ever had the opportunity to erect sheet metal plants or physics labs? Of course not, circumstance deals us the hand we get.

The ideal world provides every child an education, nourishment and safety, but that's why they're ideal worlds. Studies like Heckman (2006) and Marmot (2010) have informed Government how early interventions fight poverty, and health inequality are shown to boost cognitive potential. It seems to go unheeded. 

The Need for a Nuanced Discussion

IQ tests don't capture all intelligences: emotional intelligence, creativity, social or strategic skills as well as common sense, they aren't measured. Sternberg (2004) stressed the importance of broader measures. US and UK education systems now favour more holistic approaches because they're thorough. Most UK courts and employers have dropped IQ testing. Ironically, even people with high IQ scores speak out against confining intelligence to a number.

Conclusion 

So tell the bigots IQ test designs do not cater for everyone, as we can see by the neurodiversity gap. Of course, the most stubborn will never back down no matter how much evidence you provide. Mensa is aligned with the neurodiversity argument, the limitations of IQ testing too, and how IQ increase with better environmental factors. 

Studies such as the divided Germany score data or the unfair theistic vs atheistic results are solid. Respond to intelligent feedback: constructive feedback is welcome in the comments section. 

We can assert thst IQ is not static; it is proven to increase over time and with training results can be improved. Yet, the sophist/egotists will nit-pick, even using one, tiny inconsequence to smear as much as they can! This usually means you've written something that's probably right. 

We know IQ and education don't always meet eye-to-eye. A great specialist nurse needs significantly more skills than an IQ number can offer. A-Levels are more potent than IQ scores for career development with doctors—it follows. 

The Flynn Effect supports the idea that IQ has significantly increased over the last century because of environmental factors, like improved nutrition, and increases in reasoning-based jobs and the role of education. It shows that we can improve upon our future IQ test results through learning and practicing how to answer the questions. Above all, the G factor can't be fixed given this fact and the existence of our brain's neuroplasticity! 

Finally, sitting a test might involve applying your knowledge of formulas, theorems, problem-solving and reasoning, because knowledge is drawn from memory. Memory is definitely not untapped intelligence. In fact, throughout our evolutionary history progress came from failure, true grit, trial and error - hunting food was never closed with a one off, final and definite decision. Competitive students in countries that use IQ tests in education have real motivation to practice improving their scores (Flynn, 1987).

Ask Yourselves:

If someone like Rick Rosner can study IQ test methods and patterns only to then score over 160; does it make him a cheat? People practice this often and invalidate IQ. 

If we call this cheating we recognise the need to regulate or obscure how IQ tests award points from potential candidates. Comparable to a magician and his tricks. Why? Because cheating ourselves higher scores musn't ever be considered as learning: when we figure out how to do smash them the magic goes.

If this is not cheating, we acknowledge, by default, that intelligence is the ability to learn and overcome problems—which I say is the case. Trial and error, testing the waters, failure, familiarising oneself with the task at hand, it's all progress. 

Either way, IQ tests fail to identify fixed, innate ability with a score.

References

Becker, M. Devanna, P. Fisher, S, E. Vernes, S, C. (2018) Mapping of Human FOXP2 Enhancers Reveals Complex Regulation [Online] Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC5826363/

Flynn, J.R, (1987). The Mean IQ of Americans: Massive Gains 1932 to 1978. Psychological Bulletin.

Herrnstein, R. J, & Murray, C. (1994). The Bell Curve: Intelligence and Class Structure in American Life. Free Press.

Heckman, J. J. (2006). Skill formation and the economics of investing in disadvantaged children. Science, 1900-1902.

Nisbett, R. E, Aronson, J., Blair, C, Dickens, W., Flynn, J. R., Halpern, D. F, & Turkheimer, E. (2012). Intelligence: New findings and theoretical developments. American Psychologist, 130–159.

Marmot, M. (2010). Fair society, healthy lives: The Marmot Review. The Strategic Review of Health Inequalities in England post-2010. London: University College London.

Plomin, R, DeFries, J. C, Knopik, V. S, & Neiderhiser, J. M. (2016). Top 10 replicated findings from behavioral genetics. Perspectives on Psychological Science, 3–23.

Scarr, S, & Weinberg, R. A. (1976). IQ test performance of Black children adopted by White families. American Psychologist, 31, 726–739.

Sternberg, R. J. (2004). Culture and intelligence. American Psychologist, 59, 325–338.

Turkheimer, E., Haley, A, Waldron, M, D'Onofrio, B, & Gottesman, I. I. (2003). Socioeconomic status modifies heritability of IQ in young children. Psychological Science, 623–628.

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