Oh my god, it all makes sense:
Many hangover sufferers looking for someone or something to blame can now point the finger at their own genes, according to a new study.Mutations in a specific gene inactivate a key enzyme and slow the elimination of acetaldehyde — the first product of alcohol metabolism — from the body, say Japanese researchers reporting in the July issue of Alcoholism: Clinical & Experimental Research.”
(Via the smarty-smarty ladies of the Huffington Post Newswire.)