Why, despite the Westermarck effect, do you keep hearing stories of childhood friends becoming romantically involved as they grow up? What is the key age range for it to take effect? I know that in the past marriages between relatively close cousins happened sometimes simply because of how limited travel was, so there were limited options, and nobles and royals thought that it was beneficial for them (for some reason), but why do we sometimes hear about knowingly incestuous pairings, despite the negative effects of inbreeding being fairly well known today?