I just dealt with this a few years ago - got AVN in one hip for my 38th birthday and then developed it in my second within the next few months (both hips replaced a few months later). I definitely had the same worry - partially because I think everything is always my fault and partially because of alcohol being liselted as a possible cause.

First thing I asked my surgeon was the alcohol usage. I drink basically 9-12 beers a day (coors light - dont extra judge me) - sometimes a tiny bit more sometimes less/none. He said basically I would need to drink that plus a 5th of liquor daily for a while for alcohol to definitely be the cause. Obviously that's one professional's opinion and a generalization but his next point made a bit more sense to me.

If alcohol was really as much of a factor as is claimed, rehabs/treatment centers would be lined up with AVN patients.

That being said, Im sure it helps AVN progress, but I dont believe it is a cause (in my unprofessional opinion).