Quotes: Brother-Sister Incest

Rimmer: Well, I'd have thought it was obvious. Two people, unable to contain their desires, had an illicit liaison. A liaison that an unforgiving society would not accept. And you were the fruit of their forbidden passion. You're forbidden passion fruit.
Lister: What are you saying?
Rimmer: I'm saying, Lister, that there's a very real possibility that your parents were brother and sister.
Red Dwarf, "The Last Day"

Homer: If he marries your mother, Marge, we'll be brother and sister. And then our kids...they'll be horrible freaks with pink skin, no overbites, and five fingers on each hand! [Homer imagines the freakish kids] Aaah!
The Simpsons, "Lady Bouvier's Lover"

Jessica: Yeah the Cullens are all together, like TOGETHER together. Uh, the blonde girl, that's Rosalie, and the big dark-haired guy Emmett, they're like a thing. I'm not even sure that's legal.
Angela: Jess, they're not actually related.
Jessica: Yeah, but they live together. It's weird.

Caligula: To tell you the truth, I couldn't give a damn about Drusus and Nero.
Claudius: But they're your brothers.
Caligula: Yes, I know. But then you don't like Aunt Livilla and she is her sister. Now I love my sisters, uncle.
Claudius: Yes, I know...
I, Claudius

Azaka Kokuto: I am what you would call a troubled young lady. I am going to explain myself so there won't be any misunderstandings. I am not troubled with the fact that I love my own brother. I seriously love Mikiya to the point where I can't believe it myself. I got adopted by my uncle, entered a boarding school in Reien, and lived away from Mikiya so that he would forget about me being his younger sister.
Kara no Kyoukai

"Son of God or son of man, Marseille; you can't fuck your sister and expect much good to come of it."
Herr Starr, Preacher

Leia: Luke's my brother.
Han: Then why were you always kissing?
Atia: You fucked your sister! You little pervert!

Kyousuke: The concept of love between siblings is accepted as a legitimate theme under official publishers! Is there any difference between them? No. New stories, old ones, they're all the same!
Ayase: W-what are you doing, dragging gods into our story!?
Kyousuke: Love between siblings has always been an inherited story, ever since the era that humans first appeared!!
It wouldn't be a traditional Norfolk wedding without a speech from the father of the bride and groom.