Alcohol metabolism, which occurs primarily in the liver, follows the following pathway: Ethanol is converted to acetaldehyde by the enzyme alcohol dehydrogenase (ADH), acetaldehyde is then converted to acetic acid by acetaldehyde dehydrogenase (ALDH).
The study (link found below) found that alcoholism is more likely in some individuals due to the presence or lack of ADH or ALDH alleles. The genes ADH1B and ALDH2 were found to be the most strongly associated with the risk of alcoholic tendencies. The presence of these genes is likely to decrease your risks of being alcoholic because it either a) increases the rate ethanol is broken down to acetaldehyde, which is the toxic substance that causes hangovers and its associated unpleasant symptoms, or b) decreases the rate acetaldehyde is broken down to acetic acid. In short, an increase of acetaldehyde in the body is unpleasant and therefore, deters one from drinking excessively.
http://findarticles.com/p/articles/mi_m0CXH/is_1_30/ai_n21041751/
