From Wired magazine:
http://www.wired.com/wiredscience/2010/07/alcohol-social-gene/
Individuals who inherit a particular gene variant that tweaks the brain’s reward system are especially likely to drink a lot of alcohol in the company of heavy-boozing peers.
So, is the answer to this drinking alone? Or drop a few friends?
Or, in true BGRH style, invite all your friends around and drink even more than you normally would?