Genes, Environment, and Intelligence: Facts and Myths about Cognitive Development

We often hear the old saying: “The apple doesn’t fall far from the tree.” People usually say this when children resemble their parents in many ways — in character, behavior, or abilities. This phrase is repeated especially often when it comes to mental abilities. The logic goes like this: if parents are intelligent, then their children will inherit their intellect, and if not — there is nothing to expect.

But is everything really determined by genes? To what extent do children inherit their parents’ intelligence, and can the environment change the situation? Modern science gives interesting answers to these questions.

Nature or Nurture: Which Matters More for Intelligence?

Scientists have long studied what has a stronger impact on mental abilities — heredity or the conditions in which a child grows up. On the one hand, genes inherited from parents certainly play a major role.

According to researchers, about half of the differences in IQ scores are due to genes. In other words, children are indeed often intellectually similar to their parents partly because of heredity (and partly because parents usually create a stimulating environment at home). However, this does not mean that a child’s fate is fully predetermined by biology.

Environment and Upbringing: Intelligence Can Be Developed

It has long been known that good living conditions and upbringing help develop a child’s abilities. Now science also has concrete evidence of this. A striking example is an experiment by French scientists who followed a group of 65 children raised in disadvantaged families.

In early childhood these kids experienced a serious lack of care and education. Not surprisingly, their first IQ tests at the ages of 4–6 showed results well below normal — under 85 points (with the average set at ~100). Then all these children were adopted and placed in new families. After 5–10 years, psychologists tested their intelligence again — and found striking changes.

For most children, IQ had significantly increased over those years. Moreover, the improvements directly depended on the environment in the adoptive family: the better the new conditions, the more their intelligence grew. Children placed in well-educated, financially secure families gained on average about 15–20 IQ points and nearly reached the average level. Those raised in less wealthy but caring families improved by about 7–10 points. In other words, when a disadvantaged environment was replaced with a favorable one, these children’s intelligence rose substantially.

This experiment clearly showed that at ages 4–6 mental abilities are not yet fully formed and can progress when conditions improve. As noted by psychologist Michel Duyme, who led the study, changing the surrounding environment can significantly raise a child’s IQ. The task of teachers and educators, he believed, is to find ways to realize this potential in practice.

This raises the question: is a similar “boost” in intelligence possible if living conditions improve later in childhood? French specialists wondered whether a comparable effect would occur if a child were placed in a new family at ages 7–10. Definitive data are still limited, but it is believed that positive changes are possible even among school-age children: the brain remains plastic in both childhood and adolescence. However, the older the child, the harder it is to make up for lost early development time. That is why experts agree: the earlier a child is provided with a favorable environment, the better for their intellectual growth.

The effect of a new family is just a particular case of a broader trend. On a global scale it is also clear how improved living conditions increase intelligence. For example, in the 20th century average IQ scores in many countries steadily rose as people became more educated, healthier, and wealthier. This steady rise in intelligence across generations became known as the “Flynn Effect.” It provides yet another piece of evidence that intelligence is not static: on average, people become smarter as nutrition, education, and living standards improve.

Genes: Is There an “Intelligence Gene”?

If the environment is so important, does that mean we can ignore genes? Of course not — heredity sets a certain potential for development. However, it would be wrong to think of intelligence as something dependent on a single “smartness gene.”

For example, French researcher Michel Duyme was skeptical about attempts to “identify an intelligence gene” — and modern science proves him right. Scientists searched for specific sections of DNA directly responsible for high IQ, but never found a single “genius gene.”

It turned out that mental abilities are determined by a combination of a huge number of genetic factors — hundreds or even thousands of genes and their interactions. Each contributes a tiny part, so no single gene by itself makes a person a genius or, conversely, less capable. In recent years, researchers have identified many genes linked to intellectual abilities, but each one’s contribution is very small.

Thus, genes set more of a general “range” of possibilities, while the actual level of ability is shaped by a complex interplay of heredity and environmental influences.

Epigenetics: When Environment Changes Genes

There is another bridge between heredity and environment — epigenetics. This modern field of biology studies how living conditions affect the functioning of our genes. Simply put, events and environment can “switch on” or “switch off” the activity of certain genes without changing the DNA itself.

For example, severe and prolonged stress in childhood can chemically “switch off” some genes associated with brain development, which later affects cognitive abilities. On the other hand, positive factors — proper nutrition, care, intellectual stimulation — can instead activate genes that support nervous system development.

Scientists have already found specific examples of such influence. In one study, teenagers who had suffered serious stress in childhood showed an epigenetic “block” of a gene important for the brain’s motivation system. Those whose gene was effectively switched off had below-average IQ scores. In other words, negative experiences left a biochemical trace that prevented the full realization of their innate intellectual potential.

Some of these epigenetic marks may even be passed to the next generation — meaning that parents’ experiences can partly influence their children’s development. Although these processes are not yet fully understood, the very fact of their existence underscores: nature and nurture are much more interconnected than often assumed.

Education and Mental Training

The most important environmental factor is education. It is no coincidence that IQ test results strongly correlate with a person’s level of education. Attending school and the process of learning directly develop intelligence: a child learns to solve problems, memorize information, analyze, and draw conclusions.

Many studies confirm that additional years of schooling raise cognitive test scores. For example, if a country extends the period of compulsory education, the next generation’s average IQ turns out to be higher than that of the previous one. Even one extra year of quality education can add several points to intelligence, especially in childhood, when the brain is actively developing.

School knowledge, reading, puzzles, and other brain exercises all “train” the mind much like physical exercise strengthens muscles. That is why good education and lifelong learning help a person maximize their natural abilities.

How to Unlock a Child’s Intellectual Potential

Research clearly shows: environment and upbringing play a huge role in mental development. This means parents and teachers can do a lot to help children develop their abilities. Here are some general recommendations that, according to experts, foster intellectual growth:

• Early Communication and Reading: talk to your child from the earliest years, answer their endless “why” questions, and read books to them. Rich language and lively communication stimulate the brain and greatly expand vocabulary.
• Stimulating Environment: provide access to books, toys, and games that encourage thinking (construction sets, puzzles, board quizzes). Encourage curiosity — explore new things together, conduct simple experiments, and show your child the world around them.
• Quality Education: if possible, choose good preschools and schools where learning is engaging. Support them in their studies: help with difficult tasks, praise their efforts, and note progress.
• Health and Nutrition: take care of physical well-being. Proper nutrition (especially enough iodine, iron, and other essential micronutrients) is necessary for brain development. It is important that the child gets enough sleep and has time for play and rest — chronic stress and fatigue greatly hinder learning.
• Emotional Support: create a warm, stable atmosphere at home. A child who feels love and support is less vulnerable to toxic stress and more confident. This helps them explore new things without fear of failure and develop their talents.

Of course, no method will turn a child into a genius overnight — intelligence develops gradually. It is important to understand that everyone has their own innate characteristics, but support and favorable opportunities can sometimes work wonders.

The main thing is to show the child that the world around is interesting, that learning is exciting, and that you believe in their abilities. Then the “apple” really can fall as far from the “tree” as the created conditions allow it to develop.