This question was asked for years by James Fallon, professor of neuroscience at the University of California and advisor to the U.S. Department of Defense. He believed that our personality was predetermined by our genetics, even though this person had received a minimal moral education.
Fallon spent many years collecting brain scans and genetic sequences of psychopaths and violent criminals. He discovered that, as he thought, these criminal minds had special genetic alleles related to the manufacture of serotonin, which conditioned them to be more aggressive and less able to understand and appreciate the feelings of others.
In 2005 he published his theory on the nature of psychopaths in which he argued that criminal aggression is innate. The neuroscientist was invited to give lectures at universities around the world to explain his extraordinary discovery.
At that time, he came up with the idea of carrying out a study on Alzheimer's disease using the same technique to check whether or not genes are also determinants for developing this pathology. He took brain scans of Alzheimer's patients and compared them with those of other people in his own family who hadn't developed the disease.
When he began to study them, he realized that the brain of one of these healthy people had the psychopathic pattern he had been analyzing months before.
A bitter discovery
When he went to check which of his relatives had a criminal mind he realized that the scanner was his own. He asked his mother if she had ever noticed that he behaved like a psychopath at any time, his mother showed him a book that one of James' cousins had written about the family history of his paternal ancestors that showed that many of them were murderers in the late 19th century.
Horrified, he asked more family and friends if they had noticed that he behaved like a psychopath. They all agreed that Fallon was a risk-addicted person, as well as an edge incapable of congratulating anyone or paying their respects on a death.
The professor had to admit that even though some people are born with killer brains (like himself), the love they receive can prevent them from becoming criminals.