Honestly not aware of any alcoholics in my family. Plenty of other problems, just not that. In fact Jews have one of the lowest rated of alcoholism in the world. Chinese even lower. Yet we are not teetotalers. Probably a combination of fortunate genetics, there is some genetic predisposition to alcohol addiction, and cultural, drunkenness is severely frowned on.
As others have said and as I learned from former friend, it's damn near impossible to help someone who won't admit a problem. If your dad has a primary care doctor, try talking to him/ her. Wish I could provide a better answer.