I went with "other." It is certainly not a sin - I think that's a terribly sad thing to think/feel/believe. I'm not sure it's a disease either, in the traditional sense.
I think it's a mental illness that some of us are more susceptible to - due to genetics, traumatic experiences etc.
My mum is an alcoholic, my dad is an alcoholic. Both physically abused me. I would be in a very dark place indeed if I told myself that my own addictive tendencies were a sin!
My brain is simply not wired in the same way as someone who can drink one glass.