99 bottles of beer on the wall

You can also say that a homosexual who cannot help his/her homosexual actions is like an alcoholic who cannot help having another beer.

The difference being that homosexuality is not considered a "disease," especially since scientists don't seem to be able to find that biological tie that explains the nature of it-- not saying that it would be if it did, but you get my point.

Try searching in Google for "Alcoholism Gene" versus "Homosexual Gene" and check the first few results of each search.