The weirdest part, in my opinion

... was the sex arrangement with the security woman. I mean, the film is obviously full of weird stuff. But the rest of it made sense somehow - the parents wanted to keep their children away from the world (for whatever reason), so they invented these strange rules and explanations, and children came up with their own limited world. But how does the sex arrangement fit into this picture? Did the parents really think that, in addition to keeping the children from knowing anything about the world, there was a strong necessity to get their son laid? And this necessity was so strong that, after the security woman could not come anymore, one of the daughters had to do the job. Strange logic. In a way, it would have made more sense if the parents had tried to suppress any sexuality in their children (like some ultra religious parents would do). But this film took an even weirder road by making the parents rather liberal about sex. Interesting film!