A chromosome abnormality seems to be the most likely trigger for serial killers.
A chromosome abnormality in serial killers begins to express itself during puberty, Morrison said.
Serial killers, who are mostly men, develop and begin to display their homicidal tendencies during puberty when that chromosomal abnormality expresses itself.
While researchers don’t have an exact gene identity, the fact that serial killers are men leads researchers to believe there is “a change associated with the male chromosome make up,” Morrison said.
But researchers are still investigating how the gene changes and why it does.
Most serial killers also kill their first victim during those same teen years.