5 things that define genes
How genes determine the amount of alcohol consumed and why early stress affects our behavior all our lives
Some people tend to explain any human quality by genetics. Of course, genes do not always determine how a person looks, how he behaves and how capable he is of this or that activity. We tell you what genes may really affect, although not to the extent that we used to think.
Resistance to HIV infection
In European populations, about 1% of people are HIV-resistant. Both copies of the gene encoding the protein that serves as a "landing pad" for the virus are defective. If a person has a mutation in only one of the copies, he can still get sick, but the probability of being infected is 10-13% lower compared to those who have both copies of the gene normal. In addition, carriers of the defective gene develop AIDS for several years longer and mortality is somewhat lower. The discovery of this mutation allowed scientists to begin developing an AIDS vaccine that is designed to block this protein.
Language ability
Of course, we do not inherit vocabulary, but learn words throughout our lives, but the propensity to use language and the so-called language sense can be determined genetically. Children vary greatly in how early they learn to speak, how fluently they speak during their lifetime and how rich their vocabulary is. Psychogeneticists study the extent to which genes are able to control language abilities, and get interesting results. For example, different variants of the ROBO2 gene affect the number of words learned by a child. And the FOXP2 gene is associated with the development of speech and the development of grammar. Genes also influence success in mastering foreign languages. Learning a second language involves many of the genes that regulated the acquisition of the first language. In general, how successfully a person learns a second language is influenced by a third of the genes that control the development of the first, a third by another set of genes, and another third by the general level of intelligence. However, linguists argue that language acquisition is influenced rather not by genes, but by the inherent ability of a person to isolate structural patterns in a language and get used to them – this is the theory of universal grammar.
Stress resistance
Genes determine how a person reacts to stressful conditions and how well he is able to recover quickly after the shocks experienced. Some genes increase the likelihood of post-traumatic stress disorder: they are responsible for the work of the immune and nervous systems. In particular, the genes of dopamine or serotonin receptors affect the strength with which a person experiences a traumatic situation and how he will recover after it. Also, how a person copes with stress is influenced by the peculiarities of his immunity: people with a genetically predetermined stronger inflammatory response are more susceptible to cardiovascular and autoimmune diseases with a high level of stress.
The genetic apparatus adapts to the environmental conditions after birth. The body's reaction to stress in children and young animals who suffered a severe shock at an early age, after a traumatic event, changes for life. Experiments on baby rats that were separated from their mother for several hours showed an increase in the level of methylation of the cortisol receptor gene – as a result, the activity of this gene decreases for life. Similar results were demonstrated by children who grew up in a single-parent family as a result of the divorce of their parents or the death of one of them. In addition, early stress leads to a decrease in the ability of rats to certain types of learning. This does not mean at all that they have "bad genes": compared to well-off rats, those who suffered stress in early childhood were worse educated, but they retained the skills they already had better.
Emotionality
It is assumed that children are born with a certain emotional type and temperament: having no life experience, newborns still behave differently. This may be determined by genes inherited from parents. Studies on identical (identical) twins and comparison of the latter with non-identical ones show that genes determine whether a person will be shy or sociable, anxious or calm, and so on. If the signs of similarity are more pronounced in identical twins with identical gene sequences than in those twins who resemble each other to the same extent as half-brothers and sisters who are not twins, it can be argued that these signs have a genetic basis. Among the traits supposedly having a genetic basis are shyness, sociability, emotionality, impulsivity, a tendency to feel unhappy, the ability to adapt and a balance of positive and negative emotions. For all these traits, the genetic contribution varies from 20 to 60%.
Alcohol resistance
Humans have genes that affect alcohol consumption: they encode enzymes that oxidize ethanol. One of these enzymes converts alcohol into the toxic substance acetaldehyde, which is associated with unpleasant sensations after a hangover, the other oxidizes acetaldehyde to compounds that are safe for the body. A person's ability to drink a certain amount of alcohol depends on these enzymes: those who turn alcohol into acetaldehyde too quickly drink less.
In addition, there are genes that determine the characteristics of the transmission of a nerve impulse. All this affects the emotional state of a person and the peculiarities of his behavior. These genes may be associated with the likelihood of developing alcohol or drug addiction. However, this does not mean that genes determine whether a person will be an alcoholic or not. Nevertheless, these genes allow us to understand the molecular mechanisms of action of substances that cause addiction.
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