I've already written about how hormones influence human behavior, but this is only a fraction of the factors influencing behavior. Expanding this topic into the context of genetics reveals many other examples that sometimes determine behavior even more profoundly than hormones. For example, it's very interesting to study how the activity of certain biochemical enzymes influences such behavioral aspects as irascibility, emotionality, addiction, and susceptibility to mental illness.
Let's get a little more specific. There's an enzyme called Catechol-O-methyltransferase (COMT) . It plays a key role in the inactivation of catecholamines—dopamine, adrenaline, and norepinephrine. It plays a significant role in regulating emotional states, cognitive functions (especially in the prefrontal cortex), and stress responses, participating in neurotransmitter metabolism.
So, it often happens that people have polymorphisms in the genes of this enzyme. For example, the rs4680 polymorphism (mine and I've seen it in many others) reduces enzyme activity, causing a buildup of dopamine and norepinephrine. On the one hand, this increases a person's activity, especially if they need to work physically (deeper concentration), but on the other hand, such people can be sensitive to stress (especially when other polymorphisms overlap). Clear signs of this condition can be seen in conflicts; people with this condition begin to "break down." For example, their hands begin to shake, their speech becomes slurred, their intonation and pupils change, and sweating and sebum secretion increase (the skin becomes shiny).
Or another example, the enzyme Monoamine Oxidase A (MAO-A) breaks down serotonin, dopamine, and norepinephrine. And yes, it too is genetically "broken." When it's broken and underactive, dopamine and serotonin levels increase (this occurs with the MAOA-uVNTR polymorphism). This condition leads to a more serious picture—increased impulsivity and reactive aggression. This is especially detrimental in those with a traumatic childhood. This leads to various deviations, such as antisocial behavior, when a person displays aggression toward themselves and others for no apparent reason. I think everyone has encountered such people at least once in their lives. They may have problems with alcohol or the law, and it's difficult to have a constructive dialogue with them.
Another striking example is polymorphisms in the dopamine receptor (DRD2). For example, rs1800497 . This can reduce the sensitivity of the reward system. This means the person has insufficient dopamine at the cellular level. Such people are typically prone to addictions (nicotine, alcohol, stimulants), novelty seeking, deviant sexual behavior (such as pornography, BDSM, etc.), and procrastination.
Why do you need to know all this? Understanding these biochemical nuances will help you better understand people. This is especially important, for example, when raising children. These polymorphisms are very easily modulated and corrected by the environment, habits, and supplements, but it's important to understand them as early as possible through DNA testing.
