Different human abilities and inclinations in terms of character and behavior, of course, arise due to neurophysiological characteristics formed both genetically and under the influence of the environment. However, it is often a contentious issue to what extent these two types of factors determine a person’s personality. Disputes may especially concern the problem of violence—what is the role of innate predispositions and the social environment in which a person exists? Let’s try to provide a clear answer to this question.
Let’s start with a study examining the genetic risk of developing psychopathy in 7-year-old children. Important components of psychopathic predispositions are callous-unemotional traits, manifested by a lack of empathy, guilt, and other social emotions, as well as antisocial behavior manifested by increased aggressiveness. As this study showed, the coincidence of both components in children has an extremely high level of heritability—81%. Meanwhile, in cases where children exhibit only antisocial behavior, a moderate level of heritability is observed—30%.
The difference between these two groups of children is that representatives of the first group, in whom callous-unemotional traits are observed, are capable specifically of intentional antisocial behavior and violence. They have a high risk of developing psychopathy and a tendency toward violent crime in adulthood, and they are resistant to educational measures. Their condition is more severe than that of children in the second group, whose behavioral problems are not as serious or long-term.
Another study should be mentioned, which examined the stability of different types of aggression from childhood to adolescence. The stability of reactive aggression, which arises as a subject’s reaction to frustration or threat (defensive aggression also falls under reactive), can be explained in nearly equal measure by genetics (48%) and environmental influence—shared (11%) and non-shared (41%). However, the stability of proactive aggression, i.e., the use of aggressive actions to achieve certain goals and the intentional infliction of harm on people, was predominantly genetically mediated (85%). Furthermore, it is worth mentioning that in adulthood, a strong genetically mediated stability of callous-unemotional traits still persists. For example, between the ages of 17 and 24, it is 58%.
The ability to commit intentional acts of violence, or proactive aggression, certainly has an extremely strong genetic influence. This is consistent with the concept of the violence inhibition mechanism, according to which the average healthy individual experiences a reaction of rejection and resistance to causing harm to other people. This mechanism is expressed as an innate unconditional reflex that emerged during human biological evolution, and callous-unemotional traits and psychopathic predispositions are the result of a failure in its correct functioning.
As we can see, this impairment, leading to the capacity for intentional violence, can certainly be called a genetic abnormality, for which the best treatment would be the development of appropriate gene therapy. Strong candidates for its application could be genes associated with the correct functioning of the serotonin system, such as MAO-A, SERT, TPH2, as well as the 5-HT1A/1B receptor genes.
The situation is slightly different with reactive aggression. Its increased level is often linked to hypersensitivity to threats, and this may indicate not only a malfunction of the violence inhibitor but also of the threat response mechanisms. Since, as the concept of the threat superiority effect tells us, these mechanisms are activated both by innate threats (for example, snakes and spiders) that humans encountered during evolution and adapt to threats through acquired experience, environmental influence plays a significant role in their correct functioning alongside genetics.
