How genes influence people’s behavior, said Elena Ivanovna Nikolaeva, Doctor of Biological Sciences, Professor of the Department of Developmental Psychology and Pedagogy of the Family, Russian State Pedagogical University. A.I. Herzen, lecturer at the Imaton Institute.
Over the past 20 years, simply fantastic things have happened in neurobiology, which, unfortunately, are not implemented in any way in our practical psychology, there are no popular books on this topic. Therefore, I wanted to tell you the most important discoveries that will be useful for understanding what is happening with children.
In 2000, the human genome was discovered. Before that, a group of scientists gathered and they discussed how many genes a person can have. The Drosophila fly that flies over your grapes has 100. Perhaps a person should have more? It turned out 31 thousand. Three times less than Drosophila! Those changes in the minds of scientists that occurred after understanding what the genome is were tragic. In order to determine the genome, they took blood from the Nobel laureate Francis Crick, who discovered DNA. And when scientists looked at our DNA, they found that genes make up only 3% of DNA!
We have 23 pairs of chromosomes. And about 5 million years ago, we split from a common ancestor with chimpanzees. And I must tell you with sadness that chimpanzees and we share 98,9% of our genes. Approximately 1% are the genes that separate us. One, the most important gene, is the one that repeated 800 times and created our forehead. And the gene that transformed our throat, thanks to him we can speak. Everything else is the same for us.
The genome is the totality of all the genes of an organism contained in a haploid (single) set of chromosomes. Diploid organisms contain two genomes — paternal and maternal. But each of you must remember the following amazing thing: yes, indeed, we have paternal and maternal genes in the nucleolus, but, among other things, there are genes in the mitochondria. About 1,5 billion years ago, our eukaryotic cell took over a small bacterium that could produce energy. And then you decide for yourself whether she lives with us in the form of a slave or in the form of a warm friend, but in every cell there is a mitochondria that produces energy. Why do we know that she is not native? Because our chromosomes are rod-shaped, and in the mitochondria lies the cyclic chromosome of a bacterium …
Conrad Waddington coined the word «epigenetics» in 1942. Why do we need this word? Since the bulk of textbooks in our country are reprints of the 80s, you can still read that scientists do not know what influences a child more: the environment or genes. Scientists have known for a long time, textbooks have not yet been learned. Thanks to the term epigenetics, we can understand how the upbringing of the parents translates into altered genes in the child. And I will try to draw this picture for you.
DNA is genetics, and closing or opening a gene is epigenetics. Example: a grandmother smokes and her grandchildren will have diabetes. Only a grandmother will scold her daughter for raising her children incorrectly, although the responsibility will lie with her. A very recent discovery: those genes that saved the blockade in our city predetermine obesity and diabetes in their grandchildren. There is a closure of certain genes, which leads to a change in behavior and to a change in the functioning of the body.
How are genetics and epigenetics related? The problem is that we now know that we don’t inherit genes — we inherit the reaction rate of a gene, how a gene will react under certain conditions. For example, we take a seed from a pine tree that stands on the shores of the Gulf of Finland, plant it in a small bowl, do not water it, and get a small tree. They have the same genetics, but the conditions of existence were different. Under certain conditions, the gene manifests itself completely, while under other conditions it does not manifest itself in any way.
How are genes closed? Four bases are included in nucleotides. Cytosine under certain conditions, for example, during stress or in the first 1,5 years of life, when no one approaches the child, is methylated, a methyl group is added to it. What does this lead to? Imagine that a child has just been born, 20 cells reappear in his brain. We give him to the orphanage because the mother refuses him. The hormone cortisol is released (it is involved in the development of stress reactions), which should make sure that the brain survives. And it closes all possibilities for restoration, reparation, for division. High levels of cortisol can cause the brain to not develop. Then the brain sends a signal to our genome, to the cortisol receptor gene. In order for the body to respond to cortisol, there must be a receptor on the cell. The place where the enzyme sits down to read is called the promoter. An enzyme sits on the promoter, and the gene is read. When the level of cortisol is high, the brain sends a signal, and a methyl group sits on the promoter on cytosine. And the enzyme slips. Gene closed.
The problem is that we know the mechanism, but there is not a single person in the world who knows, at least theoretically, how this methyl group can be removed. And then in adolescence, when cortisol is released, and there are no cortisol receptors, the child resembles a car without brakes. You probably know that a large number of children were taken from orphanages after 2014. And now in some regions 60% of children are returning back because parents cannot cope with children who were in the orphanage for the first 1,5 years. All sorts of stressful situations at different stages of a child’s development lead to the methylation of certain genes, and this leads to changes in behavior.