In France, diluting your wine will get you the guillotine ;-)

The legal drinking age is 16 for low alcohol content beverages (wine, beer, etc) ; 18 for all alcohols and tobacco.

At a family gathering or on a special occasion you may get a glass of wine starting around 14 or later I'd say, for most middle class families.

Binge drinking is not as much of a problem as in more northern countries, but binge alcohol consumption is a problem that is being felt at the University level.