Do children inherit their intelligence from the mother? A controversial study resurfaces

Have you ever wondered which of the two parents transmits intelligence, or at least brain functions and abilities? A study claiming that intelligence is inherited from the mother has recently come back into the limelight, but some researchers argue against it.

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Science shows that there are conditioned genes that behave differently depending on their origin. In fact, these genes have a sort of biochemical tag that makes it possible to trace their origin and know whether or not they are active in the cells of the offspring. Interestingly, some of these affected genes only work if they come from the mother. If this same gene is inherited from the father, it is deactivated. Of course, other genes work the other way around and are only activated if passed on from the father.

We already knew that intelligence has a hereditary component, but until a few years ago we thought that it largely depended on the father. However, several studies suggest that children are more likely to inherit intelligence from the mother because the genes of the intelligence are located on the X chromosome. The genes of the mother would go directly to the cerebral cortex, those of the father to the limbic system. These new hypotheses stemming from science should dispel the stereotypes that have crossed the centuries about women.

One of the first studies in this area was conducted in 1984 at the University of Cambridge, and much research has followed over the years. In these studies, brain co-evolution and genome conditioning were analyzed to develop the theory that maternal genes contribute most to the development of thought centers in the brain. It has been discovered that there are conditioned genes, activated only when inherited from the mother, which are vital for the proper development of the embryo. Likewise, genes from the father are essential for the growth of the tissue that will form the placenta.

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The researchers believe they noticed that an extra dose of maternal genes would result in a larger head and brain, but a smaller body. On the other hand, those who had received an extra dose of paternal genes would have a small brain and a larger body. By analyzing these differences in depth, the researchers identified cells that would contain only maternal or paternal genes in six different parts of the brain that would control different cognitive functions, from eating habits to memory.

In practice, during the first days of embryonic development, any cell can appear anywhere in the brain. However, as embryos mature and grow, cells that possess paternal genes would accumulate in certain areas of the emotional brain: the hypothalamus, amygdala, preoptic area, and septum. These areas are part of the limbic system, which is responsible for ensuring our survival and is involved in functions such as sex, food and aggression. In contrast, the researchers did not find paternal cells in the cerebral cortex, where the most advanced cognitive functions, such as intelligence, thought, language and planning, develop.

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Scientists continued to study this theory. Robert Lehrke, for example, suggested that most of children's intelligence depends on the X chromosome, and he also hypothesized that since women have two X chromosomes, they would be twice as likely to inherit intelligence-related traits. Recently, researchers from the University of Ulm, Germany, studied the genes involved in brain damage and found that many of them, especially those related to cognitive abilities, are on the X chromosome. It would therefore be no coincidence that intellectual disability is 30% more common among men.

But perhaps one of the most interesting findings comes from an analysis conducted by the Medical Research Council in Glasgow, Scotland. In this study , the researchers surveyed a group of 12,686 young people between the ages of 14 and 22 each year. They took into account several factors, from the color of their skin, to their education, to their socio-economic status and found a trend: the best parameter to predict the intelligence of the child was the child's IQ. the mother. Indeed, the relationship between the intelligence of young people and that of their mother would vary on average by only 15 points.

However, several serious media claim that to say that intelligence genes are mainly transmitted by the sex chromosome X is very different from saying that the woman is responsible for passing on cognitive abilities to the child because she has two chromosomes. X. While some studies have found that a child's intelligence comes from the mother, their findings have since been invalidated by new research. This can be explained in particular by the fact that research is in full expansion in the field of genetics.