There's two issues with alcoholism, one is the physical addiction, the other is the emotional behaviors.
Growing up, I had behaviors modeled for me by my parents. These were 'normal' in our home. I also learned coping skills to deal with these unhealthy behaviors. Unfortunately, these coping skills don't work at all in the rest of the world. And I only knew the coping behaviors of my parents - which weren't healthy either.
If you go back one or two generations, do you find alcoholics there? Parents hand down their life functioning skills to their children just as they do language. We learn the emotional 'language' of our parents. When we become parents, it is not uncommon to continue to use those behaviors that were modeled to us - even if we don't drink.
Also, the term ACoA is a little bit of a misnomer. In reality, you could be an Adult Child of a Dysfunctional family - whether that dysfunction comes from alcohol, drugs, mental illness or learned behavior makes no difference, the similarities in outcome to the child will be familiar from the 13 characteristics list. While alcohol may be the most common source of dysfunction, certainly any kind of severe dysfunction can do it.