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07 August 2026 | 4 minutes read | Vojtěch Pišl | Brain facts

Are We Overestimating the Hereditary Nature of Intelligence?

IQ tests and similar assessments often lead us to view intelligence as something innate and unchangeable. But what if it’s actually quite the opposite—and we can all be smart? Mathematics can prove that there…

Are We Overestimating the Hereditary Nature of Intelligence?
IQ tests and similar assessments often lead us to view intelligence as something innate and unchangeable. But what if it’s actually quite the opposite—and we can all be smart?

Mathematics can prove that there are at least two kinds of infinity: countable and uncountable. The uncountable is greater than the countable—in layman’s terms, it might resemble “infinity times infinity” placed side by side. Even the intelligence of any given person can behave similarly to the smaller, countable infinity: while it may be limited in some ways, it is also potentially infinite. There’s no such thing as a stupid person!

Some theories assume that intelligence is largely (perhaps 80%) “innate” or “hereditary.” But what does that mean? In practice, not much. Heredity does not manifest itself in a vacuum—but rather within an environment (and in the context of upbringing). And someone who is “innately stupid” in one environment may be “innately smart” in another.

How is this possible? Imagine that beautiful roses grow in your garden. Are those beautiful flowers determined by genetics or by the environment? If the two factors operated independently, you could easily test it. You’d plant a cactus next to the roses, which would either rot in the spring or survive until fall and freeze to death. The same environment with a different result—so the difference must lie in the genes, you’d think.

Of course, this is nonsense. If you were to repeat the experiment in the subtropics instead of in a garden in the Vysočina region, you’d most likely end up with the exact opposite result: a cactus in full bloom and withered roses. The point is, it’s not about the genes alone, nor the environment (or upbringing) alone, but the combination of both.

No matter how well you care for a plant, you’d only achieve a partial improvement in an unsuitable environment. Similarly, endlessly sitting in classes and taking IQ boosters won’t turn a fool into a genius—unless they figure out what’s holding them back. In the context of our civilization, this is likely not a lack of water, nutrients, or heat—but rather destructive processes within each person’s body, brain, and way of thinking.

One of the most fundamental of these is stress—and the associated physical activation that is suitable for fight or flight but unsuitable for intellectual performance. Stress triggers a number of physiological processes that, among other things, reduce blood flow to the brain and stimulate the activation of those neural centers designed for immediate response. Reflexive reactions, impulsivity, and emotions take precedence—while the prefrontal regions of the cerebral cortex, which are essential for typically human abilities, are suppressed.

The role of stress in everyday life is well illustrated by Porges’s polyvagal theory—a theory of three different stress responses related to the activity of the vagus nerve (nervus vagus—hence “polyvagal”). In a calm state, the vagus nerve sends signals to the internal organs that everything is fine; a person is fully aware of their surroundings, feels comfortable, and everything in the body is functioning as it should.

When stress rises above a certain level that a person cannot cope with, they (gradually) “switch” to an evolutionarily older mode—and respond through the activity of the sympathetic nervous system. Simply put, over the course of a few hundred years of civilization, the body has not had enough time to learn that most modern stressors and threats require a completely different response than the one we developed over millions of years of evolution. Digestion slows down, breathing and heart rate speed up, sweating increases—and the person prepares, using all available means, for the physical activity needed to fight or flee.

If the person subsequently realizes that neither fighting nor fleeing will help, they “fall back” into the oldest stage in human history—and freeze. If one cannot flee or win, the last thing left to do is to freeze and hope that the threat will pass. In this state, as in the previous one, reason is far from playing a leading role, and intellectual and social abilities are limited.

A significant portion of human foolishness at any given moment thus does not stem from some abstract “lack of IQ”—but from a limited ability to apply one’s wisdom. A key factor here is susceptibility to stress—the extent to which a person is at peace over the long term, versus the extent to which their body is stretched to the breaking point 24/7 in an effort to keep up with and handle everything that someone else (or they themselves) demands of them. The message that follows is quite simple: calm down—and you’ll become wiser.

Article prepared for you by

Vojtěch Pišl

Vojtěch Pišl