• Personality disorders are characterized by unhealthy thoughts and behaviors that make everyday functioning significantly difficult.
  • The 10 personality disorders have each been analyzed and defined; however, there is still much to understand, such as how and why these disorders develop.
  • Many experts agree that both genetic and environmental factors are involved; in sum, the mix of the right genes and environmental influences can provide a breeding ground for these disorders.
  • Furthermore, one might inherit a certain combination of traits, of which can lead to a healthy or unhealthy outcome.
  • An individual with this set of traits might learn how to cope in their environment, while another individual (with the same set of traits) might fail to do so.

Personality disorders are a subgroup of mental illnesses that stand out for their unhealthy thoughts and behaviors, which can make day to day living extremely difficult. These disorders include: paranoid, schizoid, and schizotypal personality disorder (Cluster A); antisocial, borderline, histrionic, and narcissistic personality disorder (Cluster B); and avoidant, dependent, and obsessive-compulsive personality disorder (Cluster C). And while each of these disorders has been critically analyzed and defined, there is still much to learn and discuss. Such as what causes the development of personality disorders.

Let’s Settle the Debate: Genetic or Environmental?

Here’s the deal: it isn’t crystal clear what causes personality disorders. However, many experts agree that both genetic and environmental influences play a role. The basic gist is that certain genes may make you particularly vulnerable to developing a personality disorder, if life circumstances (environment) generate that development. Aimee Daramus, Psy.D., licensed clinical psychologist, explains:

    • “There are a few traits that are genetic, but disorders are not. The big 5 traits that are heritable include openness to new experience, conscientiousness, extraversion, agreeableness, and neuroticism. There’s a continuum of being low to high on each trait, and genetics is a big influence on where we are on that continuum.”

Life then reinforces certain traits, other traits turn out to be less useful. Things like cultural values and trauma history move us around on the continuum of each trait, within our genetic possibilities. Stress and trauma are among the things that can push us to the extremes of our genetic inheritance and when that happens, we can develop a personality disorder. So, if life pushes us to extremes, the personality disorder that emerges will be the unhealthy extreme of our genetic traits.”

Critical Combinations

Let’s look at how one’s genes and environment might come together to nurture a healthy lifestyle vs. an unhealthy lifestyle, which again can lead to the development of a personality disorder. Consider these three “big 5” traits:

  • Openness, whereas open individuals seek out and enjoy new experiences.
  • Conscientiousness, in which highly conscientious people are responsible and organized.
  • Agreeableness, whereas agreeable individuals are trustworthy and altruistic.

Daramus explains that where one falls on each of these scales can potentially create a critical combination: “Genetically high openness to new experience, low conscientiousness, and low agreeableness, for example, can lead to a healthy sense of adventure unless life pushes those traits all the way to antisocial personality disorder.”

Again, an individual who scores high on openness to new experiences is innately curious and imaginative; an individual who is far from conscientious is disorganized and unreliable; and an individual who scores low on agreeableness is unsympathetic, maybe even unkind. This combination of traits can breed a few different people:

Best Case Scenario: Jess isn’t big into the city life—too many people. Instead, she enjoys the great outdoors. Just last month, she followed her passions here and now spends her days roaming. She’s employed as a travel writer and writes about all of the new places she discovers. Her work is low pressure, and it doesn’t require her to work closely with others—much to Jess’s liking.

Worst Case Scenario: Max has always struggled in new settings. While he loves exploring the nooks and crannies of the new spaces around him, he despises meeting the people. He wishes everyone would just leave him alone. But they don’t… and so they face Max’s wrath every time they come into contact with him. He has little disregard for their wellbeing and treats them poorly. A few years ago, his psychologist diagnosed him with antisocial personality disorder.

Jess capitalized on this combination of traits to live out her desired lifestyle. She didn’t suffer as a result of these genetic characteristics, and nobody else suffered either. Max, on the other hand, struggled to live a happy, healthy life with these traits that were passed down to him. The mix of these traits and his environment led to the development of antisocial personality disorder.