The Japanese are rather conscious of the quantiy of alcohol they imbibe; this is not just a socio-cultural thing, it is also hard-wired into their DNA. A significant percentage of East Asian races have a variant of an enzyme called. alcohol dehydrogenase, which is crucial in the metabolism of alcohol. This alteration in metabolism results in elevated levels of acetaldehyde, which causes the uncomfortable flushing and other such reactions of excessive alcohol ingestion.