With only the smallest amount of alcohol some of my Asian friends will blush bright red whereas my European friends will stay pale. Why is this so? To answer this question you need to look at history:
Hundreds of years ago water was not safe to drink. People lived in unclean societies where sewage would spill out onto the street, filth would be everywhere and because of this disease easily spread throughout the population. This meant the people did not drink water as it was full of bacteria and if drank, it could lead to illness or even death. So humans had to develop an alternative drink to quench their thirst.
European cultures adopted alcohol beverages as their substitute to water. This killed off most of the bacteria in the water making it safe to drink. Because Europeans consumed lots of alcohol over the centuries they ended up developing an enzyme in their bodies which made them more tolerant to alcohol.
Contrast this to East Asian cultures where drinking boiled water with tea became the substitute. Like adding alcohol, when you boil water you manage to kill off the bacteria in the liquid. However because of this, East Asian people never managed to develop the enzyme which would have enabled them to tolerate alcohol.
Even today some Asian people will still blush fully red in the face with only the smallest amounts of alcohol. So next time you see a red faced asian at a bar, you’ll have a good idea as to why.