'Sexual Chronicles of a French Family', to give it its English-language title, pretty much does what it says on the tin! Members of a French family - including granddad - have sex. It all kicks off when the youngest son is suspended from school for masturbating in class, and while he mopes around the house his parents have sex, his sister has sex (with her boyfriend, often al fresco), his older brother has sex (as part of a threesome) and his grandfather has sex (with his long-term prostitute, who becomes a friend of the family). There's not much of a plot; just a lot of talk, and sex. Thankfully most of the sex scenes are between people whom you actually want to see naked (father and grandfather excepted - sorry chaps!) and it is interesting that although the older brother eventually decides he is homosexual, there's no explicit man-on-man action to match the heterosexual sex scenes, even in the two-men, one-woman threesome scenes.
The version of this I saw at the 2012 Edinburgh Film Festival shied away from full-frontal shots, but it's erections galore in the German cut ('Frankreich Privat Die Sexuellen Geheimnisse einer Familie', in case anyone feels like hitting Amazon.de!)