While environment certainly plays a role, you are wrong.
I have known alcoholics who were adopted as babies, raised in non-alcoholic homes, and still turned out to be drunks ... only to find their birth parents after they quit drinking, and learned that the birth parents were drunks.
Or take my own case. My parents are not alcoholic, but their parents (my grandparents) were. Furthermore, I can assure you that excessive drinking is very much frowned upon by my parents, and I was not "raised" to do it. Whatever the combination of genes is, my case (which is not unique) suggests it may be recessive.
I'm not discounting environment, Onhell. But it has long been established as fact that alcoholism is partially genetic and runs in families, regardless of environment.