The tendency to violence is transmitted like hemophilia
Murderers and rapists are born
Nika Kotova, "Newspaper.Ru"
Variants of genes that can lead to the commission of serious violent crimes have been found by scientists. However, their influence can be compensated if the child grows up in a good family.
People become murderers and rapists not only because of a difficult childhood and the wrong structure of society, but also in accordance with their biological nature. The fact that genes make a significant contribution to a person's propensity for aggression is already known to science. In a new study, the results of which are published in the journal Molecular Psychiatry (Tiihonen et al., Genetic background of extreme violent behavior), Finnish scientists analyzed the involvement of specific genes in violent behavior in a large sample of criminal offenders.
The study participants were selected in 19 Finnish prisons: out of 794 prisoners, 215 were convicted of nonviolent crimes, such as theft and drug trafficking, and 538 – for violent and 84 – for serious violent murders. The control sample consisted of 2,000 law-abiding Finnish citizens. The second independent study examined 114 criminals convicted of murder, compared with 5,000 people in the control sample.
In all groups, scientists analyzed DNA. For the first time, they managed to conduct a genome–wide association search (GWAS) - a study of genetic variants correlating with violent crimes.
As a result, they identified two candidate genes. The first gene encoding the enzyme monoamine oxidase A (MAOA) has attracted the attention of scientists for a long time. Two decades ago, experts studied several families in the Netherlands, in which from generation to generation men were characterized by a tendency to violence. It turned out that in these families, the reduced activity of the MAOA gene is inherited.
The second gene that interested scientists is the CDH13 gene, which is involved in the development of connections between neurons in the brain. Mutations of this gene have been known to contribute to the development of attention-impaired hyperactivity disorder (ADHD) in children.
The results showed that in prisoners who have committed violent crimes, and especially in those who have committed murder, the MAOA gene is characterized by reduced activity. In certain parts of this gene, one nucleotide changes to another in such a way that a smaller amount of the MAOA protein is synthesized. Scientists have calculated that the propensity to violence with this variant of the gene increases by 13 times.
The MAOA enzyme participates in dopamine metabolism. "Most violent crimes are committed under the influence of alcohol or drugs that increase dopamine levels," the authors of the article argue. – It can be assumed that a low dopamine metabolism pushes these people to take such stimulants, and then to violence. In addition, the low activity of this gene also alters the metabolism of serotonin, which leads to uncontrolled impulsive behavior."
Interestingly, since the MAOA gene is located on the X chromosome, its "aggressive" variant begins to control behavior only in men. Recall that men, unlike women, carry one X chromosome, so any "bad" gene on this chromosome is not balanced by a paired "good" one. That is, the tendency to violence is transmitted in the same way as, for example, hemophilia. In women, it will declare itself only if it appears on both X chromosomes, and this is very rare.
As for the second gene, CDH13, it has an independent effect. Scientists have found mutable regions of this gene in which certain variants are associated with violent crimes. In this case, this is due to deviations in the formation of connections between neurons.
In general, scientists estimated the contribution of these two genes to serious violent crimes – murders at 5-10%. It seems that this is quite a bit, but for specific genes such a contribution is considered significant.
At the same time, as the authors of the work specify, either one or the other "bad" variant of genes is carried by about 20% of people in the population. Are all these people potential murderers and rapists?
A very important circumstance was revealed. Scientists have shown that "bad" variants of the MAOA and CDH13 genes make themselves felt if a child grows up in a dysfunctional family, if his upbringing is not engaged or if his parents are too authoritarian.
But, as in the case of other genes, this negative can be compensated if the family has good relations and a friendly environment.
Portal "Eternal youth" http://vechnayamolodost.ru01.12.2014