I come from a very large family, and it would be a hell of a lot easier to list the ones who do NOT have a problem with alcohol and/or drugs.

I know people in my extended family were. We had a bathtub gin on the old family farm over the hill we found with lots of old moonshine back in West Virginia. That was on my father's side. I know my uncle is still (if he's still alive) a severe alcoholic (as in he drinks 2-3g of wine a day and has for the last 20 years). My grandfather was/is an alcoholic (paternal). My father is an alcoholic. My mother is an alcoholic. I know a couple of uncles on my mother's side are alcoholic's. I have some cousin's on my mom's side are alcoholics too. There are also several who chose drugs over dabbling in alcohol. Coming up on 9 months sober in 2 weeks myself. *nods* :) :)

No Irish here. Czech, German, and Hungarian mostly.

No one in my family is alcoholic, only me. Childhood sexual abuse (uncle) often results in alcoholism and depression.

both my parents are alcoholics, in recovery.

irish/german - I always used to say it's in my blood.

My grandfather was an alcoholic. Neither of my parents ever touched booze really, they are Mormon. It seems to have skipped a generation in a sense. I wish my parents had been normal drinkers because I feel like I had no real example, just "don't drink."
2 of my 4 brothers have a problem. And I am the worse.

Many alcoholics on both sides of my family, as far back as I can tell. I grew up with an alcoholic father, luckily he eventually quit and has been sober for the past 28+ years!

If it's genetic, I don't think it can just "stop" by itself. The gene will always be there. The only way to possibly prevent alcoholism in future generations is to educate them about alcoholism, from when they are very young. My mom says she doesn't really remember being told about her grandfather's alcoholism. She and her siblings were told things gradually. Obviously this won't work with everybody (my mom's brothers are an example of that), but I do think that families who carry that gene should communicate honestly about it.