Looking for the title of a paperback novel that begins in New York City, culminates in a small town in the Appalachians.
Flashback is the Appalachian family has twin boys, one appearing normal, the other...oddly hairy. Apparently the town is filled with werewolves, descriptive scenes of a preacher looking out the window of his church, and werewolves dancing around in its cemetery, and of very young werewolves (in human form) mating in the crawlspace under the, I believe, General Store.
Ending turns out it's the "normal" twin from NYC that's the werewolf, not the one still in the Appalachians. As I recall, it doesn't have 'wolf' in the title, but does have 'moon' (yea, I know, that really narrows it down....), cover is dark, full moon probably.