Scientists have identified a "drunk and disorderly" gene that could provide an excuse for cringe-making conduct at wedding receptions and office parties.
According to the Finnish study, around 2% of the country's population is cursed with the mutation that causes people to go wild after drinking.
Even a relatively small amount of alcohol is enough to set these unfortunates off on a path to social disaster.
The protein made by the gene, the serotonin 2B receptor, is believed to be linked to general impulsivity and certain mental health problems.
Lead researcher Dr Roope Tikkanen, from the University of Helsinki, said: "The results ... indicate that persons with this mutation are more impulsive by nature even when sober, and they are more likely to struggle with self-control or mood disorders."
More than 100,000 Finns are thought to carry the serotonin 2B receptor variant identified by the study, said Dr Tikkanen.
He added that behaving recklessly while under the influence of alcohol was considered a "Finnish national trait".
To date the mutation had only been found in Finns but Russians - also known for extreme behaviour when drunk - might also be carriers, he said.
The research, published in the journal Translational Psychiatry, involved 170 individuals who provided DNA samples and had their personality, aggressive traits and alcohol use assessed.
The findings could shed light on the role of the serotonin 2B receptor, which is still unclear, said the scientists.
Many antidepressants work by raising levels of serotonin, a brain chemical closely linked to mood.