Westerners could be genetically programmed to consume fatty foods and alcohol more than those from the east, researchers have claimed.
Scientists at the University of Aberdeen say a genetic switch - DNA which turns genes on or off within cells - regulates appetite and thirst.
The study suggests it is also linked to depression.
Dr Alasdair MacKenzie conceded it would not stop those moving to the west adapting to its lifestyle.
Obesity levels have risen sharply in many Western countries since the 1970s.
Dr MacKenzie, who lead the study team, told BBC Scotland they found Europeans were more inclined to consume fatty foods and alcohol - but that people from the East could end up with the same problems if adapting to a new culture.
Scientists at the university's Kosterlitz Centre said the switch controls the galanin gene.
Dr MacKenzie said: "The switch controls the areas of the brain which allows us to select which foods we would like to eat and if it is turned on too strongly we are more likely to crave fatty foods and alcohol.
"The fact that the weaker switch is found more frequently in Asians compared to Europeans suggests they are less inclined to select such options.
"These results give us a glimpse into early European life where brewing and dairy produce were important sources of calories during the winter months.
"Thus, a preference for food with a higher fat and alcohol content would have been important for survival.
"The negative effects of fat and alcohol we see today would not have mattered so much then as life expectancies were between 30 to 40 years."
He explained: "It is possible that during the winter individuals with the weaker switch may not have survived as well in Europe as those with the stronger switch and as a result those in the west have evolved to favour a high fat and alcohol rich diet."
Dr MacKenzie added: "Galanin is also produced in an area of the brain called the amygdala where it controls fear and anxiety.
"Thus, changing levels of galanin in the amygdala will have an effect on an individual's emotional state. Intriguingly, the switch was also active in the amygdala."
The study is being published in the Journal of Neuropsychopharmocology.