Who do we inherit our intelligence from? The surprising conclusions of researchers from London

• Intelligence is a 50–80 percent inherited trait, but its development is also strongly influenced by environment, diet and upbringing.
• Genes related to intelligence are often found on the X chromosome, which may indicate a greater maternal influence, especially in sons
• Research shows that there is no single "intelligence gene" - it is the result of thousands of genetic variants and their interactions.
• The final IQ level of a child is shaped by both genetic predispositions and the quality of early experiences, education and the involvement of both parents.

Intelligence is not just about taking IQ tests. It is a complex psychological construct that includes the ability to learn, think logically, analyze information, and adapt to new situations.

As research by Prof. Robert Plomin from King's College London shows , intelligence is one of the best-studied and most stable dimensions of human personality, measurable from childhood to late old age.

Modern genetics leaves no illusions – and intelligence is a strongly hereditary trait, but not exclusively. In a study published in 2023 in "Nature Genetics", scientists analyzed the DNA of over 1.3 million people. They identified over 1,200 genetic variants related to cognitive functions and educational achievements. It is estimated that from 50 to even 80 percent of differences in IQ between individuals are the result of genetic conditions.

On the other hand, the environment in which a child grows up – starting from the prenatal period – has a huge impact on the realization of genetic potential. The mother's diet during pregnancy, exposure to toxins, as well as the quality of emotional relationships and education in the first years of life can clearly modulate a child's intellectual development.

Many hypotheses assume that the genes encoding intelligence are more often located on the X chromosome. Women have two X chromosomes, while men only have one. This means that the mother can pass on more copies of genes related to intelligence to her offspring. This theory is supported by research conducted by a team from the Medical Research Council in Glasgow , which indicates a correlation between the IQ of the mother and the cognitive abilities of her children.

Moreover, some animal experiments suggest that paternal genes are more active in parts of the brain responsible for emotional functions, while maternal genes are more active in regions responsible for thinking and memory. However, this does not mean that fathers are excluded from the process of passing on intelligence.

Contrary to popular myths, there is no single gene responsible for IQ. Intelligence is a polygenic trait – it is influenced by the action of hundreds or even thousands of genes.

A study by Prof. James Lee of the University of Minnesota identified as many as 1,271 DNA variants associated with IQ and educational success.

What is surprising is that each of these genes has a very subtle effect – none of them is a “genius gene”. Only their combined effect and interaction with environmental factors determine how an individual’s intellectual potential develops.

Although research tends to favor a greater contribution of maternal genes in shaping intelligence, the father also plays an important role—especially at the epigenetic and nurturing levels. His involvement, presence, level of education, and approach to learning are all important in modeling a child’s attitudes toward acquiring knowledge.

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