Behavior and character: how much do genes determine them?

The genes that raised us 
Andrey Konstantinov, "Russian Reporter" No. 7-2011 

Soon, instead of horoscopes and psychological tests, we will look into chromosomes. Science has already accumulated a lot of information about how human genes and his psyche are connected. If you believe the representatives of the science of psychogenetics, then aggression, altruism, intelligence and many other qualities are determined not only by upbringing, but also by heredity

Now you can work with DNA and look for which molecules control behavior… Science will explain what we don't understand now — behavior, these words the famous Nobel laureate James Watson said in an interview with the "Russian Reporter" when he visited Moscow two years ago. It was about what significant discoveries are worth waiting for.

Until quite recently, there was only one tool for studying the connection between genes and the psyche — identical twins. Scientists were literally hunting for brothers or sisters who were lucky enough to be born with the same set of genes. Those specimens that were brought up in different families were considered especially valuable: only in this case can the influence of the environment be relatively clearly separated from the contribution of genes. And even then, such experiments cannot be called completely correct, because although the families are different, they usually belong to the same culture. Now, if one child from infancy grew up in the family of an American millionaire, and his identical twin brother was raised by an Indian peasant, then the data would be objective.

But the revolution in molecular biology has not left behavioral sciences aside. Since the 1990s, there has been a search for specific genes that affect behavior and character.

Back in the school biology course, we were taught that the same gene can be present in different variants — do you remember the story about Monk Mendel and bean flowers? The human psyche is not such a simple phenomenon as the coloring of a flower. But personality traits can be measured using tests. And then see which variant of a particular gene is present in the chromosomes.

Of course, it's not that simple. Each character trait can be influenced by hundreds of genes. We should not forget that it is not the mental qualities themselves that are inherited, but the biological factors that influence them. The role of genes is most similar to the volume control of a radio receiver: you can amplify or weaken the sound, but the words of the song will not change from this. Similarly, genes can increase a person's aggressiveness, but where he will direct this aggression — to beating faces or to writing thrillers — depends on upbringing, education and culture.

Altruism

We have been used to dividing people into good and evil since kindergarten. The good ones are those who let us play with their typewriter, and the evil ones are those who don't. And what is written in this regard in the genetic map, where is the "good gene" here? There is such a gene. It was found in 2010 by a group of scientists from the University of Bonn. After analyzing the DNA of students more inclined than others to donate money to charity, they focused on the COMT gene. It is associated with the production of substances such as dopamine, oxytocin and vasopressin, belonging to the class of neurotransmitters, their dynamics regulates our social behavior.

In humans, two variants of this gene are approximately equally distributed: COMT-Val and COMT-Met. Those who got COMT-Val, give to charity on average twice as much as those whose fate was COMT-Met.

The consolation of "natural egoists" can be the fact that acts of kindness are also associated with many other genes. But if COMT-Met is combined in a person's genetic passport with "bad" variants of the OXTR and AVPR1 genes, which also affect people's tendency to do noble deeds, then you are probably an insensitive egoist, no matter how much he proves the opposite!

Aggression

In the old days, theologians liked to argue about whether evil has its own essence or comes from a lack of good. Genetics clearly shows: in addition to weak variants of "good genes", there are actually "evil genes" that make people and animals behave aggressively.

Dutch geneticist Hans Brunner stumbled upon one of these genes after researching a family in which 14 men were real villains and hardened criminals in three generations. Each of them was characterized by impulsive outbursts of rage. It turned out that they are associated with a mutation of the gene encoding the enzyme monoamine oxidase-A. Conducted an experiment. Mice were "spoiled" by this gene, and the mutant rodents began to furiously rush at their fellows. Obviously, the plots of films like "28 weeks later" or "I am a legend" are not so fantastic.

And yet, in this case, we are talking rather about a rare disease: this mutation is very low frequency. And there are so many villains! There are other mutations among people that do not turn off the enzyme completely, as in that ill-fated family, but weaken its effect. Studying such people, scientists have found that if they are brought up in favorable conditions, they are no different from other boys and girls, but in bad conditions they tend to behave much more aggressively than their peers.

By the way, a group of researchers from Moscow State University led by Marina Egorova in 2009 showed that people can have a "fighting gene". But if they have developed control functions — self—control, the ability to set goals and plan their behavior - then, on the contrary, they will be distinguished by a tendency to empathy and tolerance, that is, just those virtues that aggressors lack so much. So genes are genes, and you should not forget about education.

Happiness

Everyone, of course, is the smith of his own happiness, but still it has to be forged from the material that nature has provided us with. Unfortunately, some people are born more prone to anxiety and depression than others. Twin studies conducted by Ken Kendler have shown that anxiety and depression are 40-50% determined by heredity. The "substance of happiness" was found — the neuropeptide serotonin, the lack of which provides us with anxiety and bad mood. Antidepressants, such as the famous prozac, enhance the effect of serotonin.

One of the genes regulating the amount of serotonin in the brain was investigated by D. Murphy and P. Lesh. This serotonin transporter regulator gene called 5NTT is distributed in two variants. One contributes to anxiety and longing, and the other — on the contrary.

By the way, the first variant of this gene significantly increases the likelihood of outbreaks of aggression, once again confirming the link between aggression and unhappiness. In general, if you have an unlucky variant of 5NTT when distributing genetic cards, it is better not to be stingy and install a happy one instead. Of course, if technology allows.

Intelligence

Scientists began to tinker with the "genes of the mind" in the middle of the XX century, using the twin method. There were many scandals, disputes and even accusations of falsification of results. The discussion sometimes turned from scientific to political. Conservatives believed that the mind could only be inherited from noble parents, while the left insisted on universal equality and called for improving the education system. Now the passions have subsided slightly. It is believed that intelligence is either half or two-thirds determined by genes. The question is which ones.

For the first time, the discovery of the "intelligence gene" was announced back in 1997 by Robert Plomin, who showed that the IGF2R gene was equally altered in most of the prodigies he studied. It is suggested that this variant of IGF2R is associated with a more efficient absorption of carbohydrates by the brain. The influence of this gene can explain the change in the IQ by 4 points, which is not at all small.

Masculinity

There is no doubt that many of the genes of a "real man" are placed on the Y chromosome: only males have it, and genes useful to males should accumulate on it. The journal Nature even published a comic map of the Y chromosome, which contained genes for love of beer, football and action movies, memory for jokes, inability to romantic speeches, and so on. In reality, all these traits are not directly controlled by genes, but are the result of poisoning the brain with the male sex hormone testosterone. But the details of the work of these genes are still unknown.

But something else is known: dominant males are not born. There is such a beautiful aquarium fish — haplochromis. In the presence of a dominant male, subordinate males are ugly, almost colorless, are not interested in females and sit quietly in a corner. But once the dominant is caught, the egr1 gene turns on in the hypothalamus neurons of the subordinate male, which triggers the full production of the sex hormone, and the former quiet man is rapidly transformed, gaining color, gloss and steepness.

Similar changes occur in the brains of primates, including humans: under the influence of the situation, the behavior of others and their own thoughts, whole ensembles of genes are able to turn on and off in a matter of minutes.

Constancy in love

Let's start from afar. Two species of small rodents live for themselves — prairie and mountain vole. Outwardly, they are difficult to distinguish: mice — they are mice. But the males of the prairie vole, having chosen a female, remain faithful to her all their lives, but the males of the mountain vole are promiscuous and indifferent to offspring.

Love to the grave in male rodents, as in male humans, is associated, among other things, with a neurotransmitter called vasopressin. If a male monogamous vole is injected with this vasopressin, he will love the first female he meets forever, but if he blocks the receptors that respond to vasopressin, he will begin to lead a promiscuous sexual life.

The difference in behavior between faithful and unfaithful mice depends on the variant of the vasopressin receptor gene. By changing this gene, you can force a polygamous male to become a faithful husband. Now it's clearly time to move on to people.

A study conducted in 2006 in Sweden showed that in men with one of the variants of the RS3 334 gene, the occurrence of romantic relationships is half as likely to lead to marriage as in others. If they do get married, they are twice as likely to be unhappy in marriage, and their wives are most often dissatisfied with family relationships. Now do you understand why all girls should study molecular biology?!

Homosexuality

The number of species of living beings in which zoologists have spied homosexual contacts is approaching five hundred, and all of them relate to same-sex love much calmer than us. Maybe it's the genes, not the Western propaganda?

And yet, yes, the research of J. Bailey and R. Pillard showed that in identical twins, the similarity in homosexuality is 50%, and in fraternal twins — only 24%. For a sensation in the press, it remained to discover the "homosexuality gene", and soon it was found by Dean Hamer: the Xq28 site at the upper end of the long arm of the X chromosome will serve as a mark in your genetic passport about the increased likelihood of craving for members of your own sex. Check this section before posting the decoding of your genome online!

For a long time, scientists have been haunted by the question of why the genes of homosexuality were not eliminated by natural selection, because love is love, and children do not come from such relationships. One of the most popular theories claims that homosexuality is a consequence of selection for bisexuality. "Feminized" bisexuals could survive in male communities, finding friends and patrons in long military campaigns, and they were in demand among women, as they were non-aggressive and caring fathers.

Religiosity

Scientists, for whom, as you know, nothing is sacred, have suggested that religiosity may also be related to genes. And indeed, there is evidence that identical twins have more similarities in matters of spirituality.

And in 2004, Dean Hamer (the same brawler who discovered the "gene of homosexuality") published the book "The Gene of God: How Faith is fixed in Our Genes", in which he associated different variants of the VMAT2 gene with a tendency to religiosity and its absence. Spiritual people, not to mention persons invested with dignity, of course, were enraged by such a harmful book. And they were absolutely right: the test showed that VMAT2 variations explain only about 1% of the differences in religiosity, and the quality of the study itself, published not in a scientific journal, but only in the form of a popular book, is questionable. But it got on the cover of Time.

Passion for adventure

The D4DR gene from chromosome 11 encodes the dopamine receptor, a substance associated with the work of the pleasure center in our brain. A mouse with a damaged dopamine gene doesn't want anything and eventually starves to death, but once you inject a dose of dopamine into its brain, it becomes extremely inquisitive, prone to risk and recklessness. People who lack dopamine also become inhibited and inactive, and those who have too much of it are always looking for new sensations.

The D4DR gene has "short" and "long" variants. People with the long option are less sensitive to dopamine, so they need something special to feel the inner encouragement. Dean Hamer, who also had a hand in D4DR research, called it the "adventure gene" in his characteristic manner. If a long variant of D4DR is indicated in your genetic chart, you are most likely easy-going, inquisitive and extravagant, prone to breaking the rules. In addition, the possession of this gene variant increases the risk of alcoholism and drug addiction.

However, it's not so scary: according to Hamer, this gene only determines the propensity for adventures by 4%, although in general it depends on genes by 40%. It's just that it, like other personality traits, is influenced by dozens and hundreds of genes. And who said that psychogenetics is easy?

Political preferences

At one time, Karl Marx was looking for the basis, the basis of any ideologies in the economy. Now it is fashionable to look for such a basis in the brain, or even directly in the genes. A number of independent studies of separated twins have shown that adherence to conservative or liberal ideology is largely hereditary: at least a third of the variability in political views is explained by genes. Often, already at preschool age, it becomes clear whether a person will be a "soil worker" or a "reformer" when he grows up.

The first contender for the proud title of "gene of liberalism" is still the same long version of D4DR, associated with a love of everything new ("gene of conservatism" is a short version of D4DR). But it was not possible to prove the connection of variants of this gene with political preferences for a long time.

It was only at the end of 2010 that an article by J. Fowler, in which, based on the data of a long-term study, he showed that this relationship is not direct, but depends on a combination of two factors: the gene variant and the number of friends in his youth. The probability that you have a freethinker in front of you increases dramatically if a person has a long version of D4DR, and at school and institute he had a lot of friends.

They explain it this way: if a person who loves everything new communicates with a large number of different people in his youth, he learns to be sympathetic to different views of the world and in the future will be more tolerant of non-traditional ideas, that is, he will become a liberal.

As you can see, the genetic map is still not enough to predict exactly how many genes will "play" in human behavior.

Portal "Eternal youth" http://vechnayamolodost.ru 28.02.2011