I have no problem with nudity in films, nor do I have any problem with children seeing nudity in films.
(BTW, are any of you aware that the Harpies in the Night On Bald Mountain segment of Fantasia are topless with nipples? So much for Disney being for children-only.
)
What I have a problem with is POINTLESS nudity or sex in a film. That is, sexual content that has no bearing on the story, importance to the plot, or not part of the character's personality whatsoever. Same goes for violence.
As for with horror films, I have no problem with horror-comedies along the lines of Friday the 13th having gratuitous amounts of sex and violence; they're comedies after all. They're supposed to be enjoyable.
But I've seen PLENTY of great horror movies that had NO nudity, and for that matter LITTLE TO NO violence whatsoever. (Psycho, anyone?
) But I wouldn't show that one to my kids because of Hitchcock's psychologically disturbing style. I wouldn't necessarily forbid it, but I wouldn't feel to comfortable with it. But if my teenager wanted to watch Friday the 13th, I wouldn't stop them.