Somewhere in this crazy list I think I have a short essay on this effect. I'm still unclear how much of kin avoidance in mating is a matter of boredom/familiarity (Westermark Effect) and how much is attributable to fear of mom, dad, and general social embarrassment.
It seems plausible that Oedipus would not have jumped Jocasta if they had not consulted a fortune teller and shipped the kid off someplace. There's an old saying that if you fear something enough, you can make it happen.