Bleeders (1997)

aka Hemoglobin, aka The Descendent

How bad is it? It's a failure and it lacks pace.
Should you see it? No, but I'm surprised by how many have seen it already.

This was based on the H. P. Lovecraft story "The Lurking Fear" and the screenplay was written by Dan O'Bannon and Rutger Hauer is in it in a minor role, so this must have disappointed a lot of people. A guy with a serious genetic disorder researches his family history and finds that he's descended from Dutch royals who inbred and moved to a small island off the east coast of America (New Brunswick, I believe, substituting for possibly Maine). There he finds that his relatives haven't died or disappeared, but gone underground, inbreeding beyond the point of monstrosity and living off the bodies of those buried in the cemetery - though the island is small enough that this doesn't make sense. There's brief nudity at the start and near the end, a fetus pickled in formaldehyde gets eaten and the guy - spoiler alert - chooses his mutant kin over his girlfriend. The film is so slowly paced that it's hard to keep watching.