Woo-jin, the villain from Oldboy, is similarly skinny, smartly-dressed, and doesn't fight his own battles. But unlike Commodus, he actually succeeded in having sex with his sister. So, score for him? I'm not sure how the points system works for succeeding in something so awful. GOOOOAL, I guess. Someone, please help.

And how could we forget the Mount Rushmore of Fictional Family Humping: Game of Thrones. There are way too many bad guys there with autumn fetishes (because they like to pump kin), so let's focus on the prissy and effeminate Viserys Targaryen. Not only does he not see anything weird about brothers sleeping with sisters, he's actually the product of generations of inbreeding. Interestingly, he's also the spitting image of Prince Nuada Silverlance from Hellboy II, who also wanted to get with his sister.

Universal Pictures, HBO

The trope is sometimes played for laughs like with the Van Waldenberg siblings from Blades of Glory, or the McPoyles in It's Always Sunny in Philadelphia, all of whom liked to exchange saliva that contained at least 50% of their own DNA. And you might have noticed that these examples of cinematic incest are all between brothers and sisters. That's because ...

There were also two sibling incest jokes on American Dad where Steve a) passionately kissed his sister after being tricked into believing he was adopted, and b) unknowingly masturbated repeatedly to his sister's nude portrait. Then in Joe Dirt, the main character joked that he pretended the girl he was sleeping with was his sister, but it was less of a "haha" joke and more of a "haha, I'm laughing which totally means I didn't really do it haha please believe me" joke.

It's Always Sunny in Philadelphia also had an incest joke about one of the characters thinking he accidentally made a nephson with his sister, which is fitting considering that the show takes place in the city of brotherly love. Likewise, Married... with Children, Buffy the Vampire Slayer, and Firefly have dealt with heavier subject matters before so it wasn't that big of a shock when they had a laugh about siblings possibly being in Lannister with each other.

However, the incest jokes almost always boiled down to "Isn't it hilarious to imagine these people actually being into/IN their family members ... you know, because they're really not. We're normal! Of course WE don't fantasize about this stuff! There's no need to check our browsing histories. Haha!" Even when siblings engage in a passionate tongue battle like in EuroTrip, it's still played for laughs because no actual sex is involved, as if Frenching your sister instead of straight-up boning her made baby Jesus weep less. This holds true even with notoriously unfunny shows like Game of Thrones where purposeful, full-penetration incest is the source of drama, but ACCIDENTAL, second base incest is just a wacky, comedic mishap, no different than slipping on a banana peel and landing hand-first on your sister's boob.

In Hollywood, any joke about two consenting adults is fair game, even if those adults are siblings and the joke is that they almost got some non-strange strange. That's why parental incest is almost never joked about because there can never be true "consent" between a parent and child. A parent and child share an unfair dynamic where one exerts immense influence over the other, so even an adult child could never really "agree" to having sex with their parent. And now having written that, I'm going to take a shower to wash the shame away. Be right back.

Alright, so, stuff like that is why parental incest is almost always a serious matter, like in Chinatown, a movie that is almost a perfect anti-comedy. Or look at Family Guy. It's made tons of jokes about the brother-sister duo of Chris and Meg practicing kissing or taking baths together, but the punchline to their first joke about Chris sleeping with his mother was the family's dog Brian banging a table in shame and screaming: "It's wrong!" No joke there. Just horrible trauma for everyone involved ... The kind of trauma that actually drove the badass Jimmy Darmody on Boardwalk Empire to run off and enlist for World War I after his mother seduced him. And, of course, it had to be her doing the seducing because:

On an episode of American Dad, the family's daughter Haley starts to date her father's CIA body-double, who looks, acts, and talks exactly like him. And unlike with the previous shows I mentioned, she is totally aware of it. She just ... doesn't think there's anything wrong with having her own fatherly doppelbanger. Another example comes from Californication, where the character Becca dates a guy who is essentially a younger version of her father in every possible way, from their intellect to their temperament. And everyone can totally see it, including Becca, though she seems to be the only one not creeped out by that fact. In a show that was seemingly totally about fifty-two-year-old David Duchovny plowing his way through the millennial population of Southern California, it was by far the most unsettling part.

Movies are really weird about women on the best of days, but women sexuality tends to be a whole other universe of weird assumptions and backass-ness. Hollywood ladies are usually either prudes with chastity belts made out of spikey ice, or insatiable perverts that only really care about getting some (penis), no matter where it comes from. It works for the writers' late-night fantasies because if a woman doesn't really care who she's having sex with, it might mean the writers themselves could have a chance with her. But it makes for some really weird writing that starts at virtual incest but then keeps going until it dives off the Cliff of Decency straight into the Chasm of Awkward Family Movie Night.

That's why in Cruel Intentions you have Sarah Michelle Gellar seducing her stepsibling, or why on True Blood, a vampire is freaked out when he discovers he's been dating his great-...-granddaughter while she is all just: "Oh come on, incest is all relative!" On a similar note, in Machete, one of the antagonists feels sick over his incestuous feelings for his daughter all while, as it turns out, his daughter is doing porn with her mom. She wasn't attracted to her or anything. She just thought that doing mom-daughter porn would get her a lot of viewers, and so she didn't mind getting intimate with her parent. That's another thing: women being way too OK with incest often also comes down to them using sex as a weapon in the unrelenting pursuit of their own goals, even if it means aiming their sex-guns at their own family.

For example, in the 2011 remake of Conan the Barbarian, Rose McGowan tries to seduce her sorcerer daddy in her quest for power, but him being a man and all, he rejects her. A similar thing happened in Grifters when a mother tried to seduce her son to try and get away with murder, but he was having none of it.

The sinful pinnacle (sinnacle) of this trope is definitely Shameless (the U.S. version) where one character gets raped and made pregnant by her dad. But because the girl claims the dad was drunk and maybe didn't know who he was doing it with, she is KINDA OK with the whole situation. Although she later got an abortion, she basically rationalized the pregnancy as just one of those annoying things that sometimes happen in life while the audience thanked God Almighty they weren't watching this episode with their family. Conversely, when a man was tricked into getting a handjob from his sister in National Lampoon's Class Reunion, he had the common decency to go insane and become a deranged serial killer. Because he's NORMAL!

Cezary Jan Strusiewicz is a Cracked columnist, interviewer, and editor. Contact him at c.j.strusiewicz@gmail.com or follow him on Twitter.

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