A new study may finally explain why some people transform from a pacific state to blind rage under the influence of alcohol.
The researchers found that a single DNA change that blocks a gene known as HTR2B disposes people to act aggressive when drunk.
It affects serotonin production and detection in the brain.
"Carriers of the HTR2B variant who had committed impulsive crimes were male, and all had become violent only while drunk from alcohol, which itself leads to behavioural disinhibition," the Telegraph quoted Dr David Goldman at National Institute on Alcohol Abuse and Alcoholism in Maryland, USA, as saying.
In the volunteers the team studied, the researchers found that the violent crimes committed by individuals were spontaneous and purposeless.
They found the association with HTR2B gene and then conducted studies in mice and found that when the equivalent gene is knocked out or turned off, mice also become more impulsive.
"Impulsivity, or action without foresight, is a factor in many pathological behaviours including suicide, aggression, and addiction," said Goldman.
"But it is also a trait that can be of value if a quick decision must be made or in situations where risk-taking is favoured."
The study appears in Nature.