Researchers have found that genes may partly determine why some people get hangovers after a night of drinking while others do not.
In a study of twins, scientists looked for links between the study participants' genetic makeups and the number of hangovers the individuals reported experiencing in the past year.
The results showed that genetic factors accounted for 45 per cent of the difference in hangover frequency in women and 40 per cent in men.
In other words, genetics accounts for nearly half of the reason why one person experiences a hangover and another person doesn't, after drinking the same amount of alcohol, the study said.
The other half probably comes from outside influences unrelated to DNA, such as how quickly a person drinks, whether they eat while they drink and their tolerance for alcohol.
The researchers also found that the people who had the gene variants involved in an increased risk of having hangovers also drank to the point of being intoxicated more frequently than people who didn't have the hangover genes.
The genes that dictate how frequently a person gets hungover may also underlie how frequently someone gets drunk in the first place, researchers said.
"We have demonstrated that susceptibility to hangovers has a genetic underpinning. This may be another clue to the genetics of alcoholism," study leader Wendy Slutske, a psychology professor at the University of Missouri-Columbia, told 'Live Science'.
In the study, about 4,000 middle-age people from the Australian Twin Registry participated in a telephone survey, reporting their experiences with hangovers and alcohol consumption.
The participants recounted how many times they had gotten drunk in the past year, along with their "hangover frequency," which is the number of days in the previous year they felt sick the day after drinking.
They also reported their "hangover resistance," which was whether or not they had ever experienced a hangover after getting drunk.
The researchers found a strong correlation between identical twins in reports of hangover frequency as well as hangover resistance, suggesting that the genetic similarities of some twins played a part in their hangover susceptibility.