A proportion of adults are (or claim to be) 'immune' from developing hangovers after heavy alcohol consumption. Estimates vary as to the prevalence of 'hangover resistance'.
A 2008 study from the US put the figure at around 23 percent.
A 2017 study from Canada put the figure at around 5 percent.
The underlying biochemical process(es) that may exempt some drinkers from hangovers is currently unknown.