Westermarck effect
I watched this film on an Etihad flight last week. They cut out all the sex scenes, so the start of the film was hard to follow.
I was wondering about the Westermarck effect, whereby children raised together don't become sexually attracted to one another.
https://en.wikipedia.org/wiki/Westermarck_effect
Wikipedia suggests that the effect is disputed. I'm no psychologist, but it sounds right to me. Isn't this why we don't fancy our siblings and cousins, however pretty they might be?
Shouldn't this have prevented attraction between Rosie and Alex? Is this addressed in the novel anywhere?