According to MedlinePlus, a service of the U.S. National Library of Medicine, a sociopath, otherwise known as someone with antisocial personality disorder (ASPD), displays long-term problems with behaviors—often criminal in nature—that “manipulate, exploit or violate the rights of others.” The cause of this disorder is unknown; however, genetics and environmental factors influence its development 12.

Causes of Personality Disorders

Personality makes each individual special and consists of thoughts, feelings and behaviors, according to the Mayo Clinic 1. These factors shape perception or how an individual interacts with and views his world. Personality is forged during childhood via the interplay of genetics and environmental factors. Problems with inherited genetics or the early environment, such as significant exposure to abuse and/or violence, make it more likely that a personality disorder such as ASPD will develop 12. Therefore, in order to understand the cause of ASPD, both genetics and the environment need to be explored.

Interplay Between Genetics and the Environment

Dr. Martha Stout, in her book, “The Sociopath Next Door,” explains that a genetic presdisposition for socipathy may already present at birth for some people 3. Determinations regarding how this increased risk for ASPD become expressed come from an individual’s life experiences.


Studies, such as the Texas Adoption Project, involving heritability factors—how much an observable trait can be explained by genetics—consistently determines, according to Stout, “that indeed a person’s tendency to possess certain sociopathic characteristics is partially born in the blood.” In other words, a person develops sociopathy because she was born that way.

Brain Differences

The brains of nonsociopaths will react faster to emotionally charged words, such as "love," "happy" or "hate," than neutral words, such as "television," "grass" or "sky." An individual with ASPD will not show this difference in reaction time; his brain responds the same to "love" as to the word "chair." Further, the brains of normal individuals demonstrate the ability to solve a problem regarding emotional words almost instantly. Meanwhile, the brain of a sociopath in response to this task shows increased blood flow to the temporal lobe, part of the brain used for analytical thinking, operating like it’s an algebra problem.

Environmental Factors

Stout writes that “biology is half the story” in the cause of sociopathy—environmental factors account for the other half of the explanation. These specific factors remain unclear. While child abuse seems an obvious determinant, some evidence suggests that sociopaths are less influenced by childhood experiences than normal individuals.

Attachment Disorder

An infant’s inability to form an appropriate bond with a caregiver, either through parental neglect or abandonment, may lead to the development of an attachment disorder. As a result, these individuals do not develop the ability to form emotional connections to others. Stout cites this factor as another probable cause for ASPD.