Scientists have discovered more than 1,200 small genetic differences linked to personality, including the traits that determine if someone is a psychopath.
An international team led by psychologist Ted Schwaba of Michigan State University uncovered 1,260 DNA variants linked to the so-called Big Five personality traits – extraversion, agreeableness, conscientiousness, neuroticism and openness.
Each one appeared to have only a tiny effect on a person’s behavior, according to personality tests, and each variant only seemed to influence one specific trait.
However, the study of more than one million people determined that up to 16 percent of the differences in someone’s personality scores were attributable to DNA variants visible before that person is born.
Although the study did not specifically examine psychopaths, Schwaba noted that the links could help the medical field determine who may be more at risk for mental health problems in the future.
‘Genetic variants associated with neuroticism predict more time spent in the hospital, which is relevant to physicians and health researchers,’ Schwaba said.
Meanwhile, the study may also help researchers understand why certain people take more risks in life or suddenly change careers.
‘Variants associated with openness to experience are linked to income and switching jobs, which is relevant to vocational researchers,’ the study author added.
Scientists have discovered 1,260 genetic variants tied to the ‘Big Five’ personality traits, including those tied to psychopathic behavior (Stock Image)
The researchers noted that their goal was to find out which common differences in DNA were linked to the Big Five personality traits, and whether those links hold up across people from different countries, ages groups and families.
They also wanted to see whether personality-related genes were connected to real-life outcomes such as health, career success and the development of mental illnesses.
The international team combined DNA and personality questionnaires from 46 patient groups. In total, they studied between 611,000 to 1.14 million people, making this the largest study of its kind.
They scanned millions of common DNA differences and then checked the results by comparing some of the participants to their relatives, so shared family life would not be mistaken for a genetic effect.
They found 1,260 DNA variants linked to personality, including 824 that have never been clearly tied to these traits until now.
However, those common variants still explained only a small share of why people act differently from one another – usually about five to nine percent of personality scores, and up to 16 percent in some analyses.
‘There is no single “personality gene,”‘ Schwaba said in a university release. ‘Personality traits are associated with many genetic variants, but even the largest effects of individual genetic variants are still very small.’
‘However, even though any individual genetic variant makes very little difference in personality, the effects of many variants together can be more sizeable.’
Roughly two-thirds of the 1,260 genetic variants linked to personality have never been associated with the ‘Big Five’ personality traits before (Stock Image)
Psychopaths are most often described as callous, uncaring and impulsive – typically tied to lower levels of agreeableness and conscientiousness.
Neuroticism does not completely define them as a group, though research in the journal Psychological assessment has shown hot-tempered psychopath types can show more anger and emotional instability.
DNA patterns linked to higher neuroticism – a tendency toward worrying, mood swings and emotional ups and downs – were also linked to higher genetic risk for many mental health conditions.
This new study, published in Nature, noted this was especially true for people who ‘internalize’ problems, where distress is turned inward, often leading to depression, anxiety and anorexia.
The same pattern also showed up across a wider set of conditions, including bipolar disorder, schizophrenia, ADHD, autism, borderline personality disorder and obsessive compulsive disorder.
Conversely, DNA linked to conscientiousness – the trait of being organized, responsible and self-controlled – was tied to lower genetic risks for ADHD and autism.
However, it was tied to a higher genetic risk for compulsive conditions such as OCD.
Overall, the researchers noted that each individual gene variant moved the needle of personality by a tiny fraction – moving someone from the 50th percentile to about the 50.35th, according to their best guess.
They estimated that thousands of common DNA differences likely contribute to each of the major personality traits, possibly just over 16,000 per trait.
