It isn’t universal, though. I remember an interview with Shirley MacLaine in which she regretted never getting to do a love scene with Warren Beatty. She might not have been serious, though.
Chyler Leigh and Christopher Khayman Lee in the umm… classic… Kickboxing Academy. To quote/paraphrase a in her most famous movie, they’re related “only by blood!”
I’m glad that Yara doesn’t have bad mockney. “Oy! Guvnah Theon!”
Gay relationships lead to incest. Got it, Rev. Robertson. 
No, you are mistaken. They never, ever alluded to incestuous themes. You are reading too much into it.
The taboo is sociological, not biological. Not that i’m against, but just saying…
I tend to subscribe to the Westermarck effect. (Which is just a hypothesis, lacking conclusive evidence.) I’m not entirely sure if the effect would be said to be nature or nurture, but in either case I don’t think incest is a taboo because of sociological pressure. I think that there is sociological pressure because incest is taboo.
I wonder if it’s a qualification of this board that the poster must possess a biological nitpicking instinct or something. That is really not the point here.
Like, Michael Madsen was a handsome man and Virginia Madsen was and is a beautiful woman, and I personally would not have a problem with kissing either one of them. That doesn’t mean that they should be asked to kiss because, whattsamatta, you’re professionals, right? Just pretend he’s NOT your brother. Uh, no.
That one would be psychological.