In a conversation with a coworker who is Navajo I asked why the Navajo didn't open casinos like the other tribes to bring in money. His reply was, "We already have alcohol and drug addiction. Should we add gambling addiction to our misery?" Just one man's opinion but he clearly saw a generalized tendency for addiction in his tribe. But he could have been speaking from stated views of tribal leadership too.

What you wrote is a strong case for alcoholism being specific to alcohol, neither affirming nor denying a generalized tendency for addiction in general.