…they (his girlfriend) came to live in the house they were (possible inherit) which they had to take a boat I think to get to this house, if I’m not mistaken could’ve been a secluded lil island but when they were there, he found out that his family are cannibals living underground… Ask me the year I’m not sure but around 80’s 90’s… The guy was blond
Try “Bleeders” (1997).
http://en.wikipedia.org/wiki/Bleeders_%28film%29
http://www.imdb.com/title/tt0119279/?ref_=nv_sr_1