Any Sexual content?

[Paddy™]

Light spoilers (potentially, but not really):

Spoiler below!

There's a nude human corpse at one point in the game (laying face-down but you can see his willy if you crouch at his ass, which I did without shame or irony) and there's some text in a note about the writer holding his penis in front of a mirror. There are some sexual inferences which can be made from some of the flashbacks/memories and the existence of two-way mirrors looking into rooms but nothing explicit.

There are a few classical paintings on the walls of the mansion which show a boob or two, and a black and white photograph (which appears to be genuine) can be seen in one of the areas of the game showing a pair of boobs.

I'm not entirely sure but I think the monsters might have visible genitals. It's difficult to get a good look

There may be more than I've listed here but this is what I've noticed personally.

I think it's probably safe to say that in terms of nudity you'll be looking at a rating ranging from PG-13 to 15. As mentioned by the previous poster you'll probably have more concerns with the content of the story.