Humans often turn to alcohol when they are either stressed or depressed. Some people get hangovers after drinking, while others don't, and the reason may be in their genes. 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. Genes interact with environmental factors to influence how much we drink, and our susceptibility to becoming dependent on alcohol. Also it is worth remembering that differences in individual’s experiences of hangover are only half genetic and those environmental factors. Scientists discovered that those people, who had the genetic variants involved in increasing the risk of suffering a hangover, also drank to excess more regularly than those lacking the hangover genes.