Behavioral genetic studies have identified potential genetic and non-genetic contributors to<unk> , including influences on brain function. Proponents of the triarchic model believe that<unk>  results from the interaction of genetic predispositions and an adverse environment. What is adverse may differ depending on the underlying predisposition: for example, it is hypothesized that persons having high boldness may respond poorly to punishment but may respond better to rewards and secure attachments. Genetic Genetically informed studies of the personality characteristics typical of individuals with<unk>  have found moderate genetic (as well as non-genetic) influences. On the PPI, fearless dominance and impulsive antisociality were similarly influenced by genetic factors and uncorrelated with each other. Genetic factors may generally influence the development of<unk>  while environmental factors affect the specific expression of the traits that predominate. A study on a large group of children found more than 60% heritability for "callous-unemotional traits" and that conduct problems among children with these traits had a higher heritability than among children without these traits. Environment From accidents such as the one of Phineas Gage, it is known that the prefrontal cortex plays an important role in moral behavior. A study by Farrington of a sample of London males followed between age 8 and 48 included studying which factors scored 10 or more on the PCL:SV at age 48. The strongest factors included having a convicted parent, being physically neglected, low involvement of the father with the boy, low family income, and coming from a disrupted family. Other significant factors included poor supervision, harsh discipline, large family size, delinquent sibling, young mother, depressed mother, low social class, and poor housing. There has also been association between<unk>  and detrimental treatment by peers. However, it is difficult to determine the extent of an environmental influence on the development of<unk>  because of evidence of its strong heritability. Brain injury Researchers have linked head injuries with<unk>  and violence. Since the 1980s, scientists have associated traumatic brain injury, such as damage to the prefrontal cortex, including the orbitofrontal cortex, with<unk> c behavior and a deficient ability to make morally and socially acceptable decisions, a condition that has been termed "acquired sociopathy", or "pseudopsychopathy". Individuals with damage to the area of the prefrontal cortex known as the ventromedial prefrontal cortex show remarkable similarities to diagnosed<unk> c individuals, displaying reduced autonomic response to emotional stimuli, deficits in aversive conditioning, similar preferences in moral and economic decision making, and diminished empathy and social emotions like guilt or shame. These emotional and moral impairments may be especially severe when the brain injury occurs at a young age. Children with early damage in the prefrontal cortex may never fully develop social or moral reasoning and become "psychopathic individuals ... characterized by high levels of aggression and antisocial behavior performed without guilt or empathy for their victims". Additionally, damage to the amygdala may impair the ability of the prefrontal cortex to interpret feedback from the limbic system, which could result in uninhibited signals that manifest in violent and aggressive behavior. Other theories Evolutionary explanations<unk>  is associated with several adverse life outcomes as well as increased risk of disability and death due to factors such as violence, accidents, homicides, and suicides. This, in combination with the evidence for genetic influences, is evolutionarily puzzling and may suggest that there are compensating evolutionary advantages, and researchers within evolutionary psychology have proposed several evolutionary explanations. According to one hypothesis, some traits associated with<unk>  may be socially adaptive, and<unk>  may be a frequency-dependent, socially parasitic strategy, which may work as long as there is a large population of altruistic and trusting individuals, relative to the population of<unk> c individuals, to be exploited. It is also suggested that some traits associated with<unk>  such as early, promiscuous, adulterous, and coercive sexuality may increase reproductive success. Robert Hare has stated that many<unk> c males have a pattern of mating with and quickly abandoning women, and thereby have a high fertility rate, resulting in children that may inherit a predisposition to<unk> . Criticism includes that it may be better to look at the contributing personality factors rather than treat<unk>  as a unitary concept due to poor testability. Furthermore, if<unk>  is caused by the combined effects of a very large number of adverse mutations then each mutation may have such a small effect that it escapes natural selection. The personality is thought to be influenced by a very large number of genes and may be disrupted by random mutations, and<unk>  may instead be a product of a high mutation load.<unk>  has alternatively been suggested to be a spandrel, a byproduct, or side-effect, of the evolution of adaptive traits rather than an adaptation in itself.
Psychopathy
Gemütlose psychopathy
Externalizing disorder
Internalizing disorder
Tic disorder
Agoraphobia
Personality pathology
Kleptomania