History Main / RelativeError

* In ''Baka & Test'' Akihisa attempts to keep his sister who has just recently moved home hidden from his friends for fear of her embarrassing him. When they start getting suspicious and go to his house they believe that he has a secret live in girlfriend, much to Himeji's denial:
"Akihisa-kun, this bra is way too big for you. You need a smaller cup size."

* In "Baka To Test To Shoukanjuu" Akihisa attempts to keep his sister who has just recently moved home hidden from his friends for fear of her embarrassing him. When they start getting suspicious and go to his house they believe that he has a secret live in girlfriend, much to Himeji's denial.
"Akihisa-kun, this bra is way too big for you. You need a smaller cup size."

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* In DavidEddings' ''TheBelgariad'', Ce'Nedra makes this mistake about Belgarion and his cousin. Her response to being corrected is, amusingly, equal parts "Whew, he's not attached" and "Shit, I'm in love with him!"

* Averted in ''NorthangerAbbey'' when the heroine sees her LoveInterest with another woman on his arm and immediately comes to the correct conclusion that it's his sister, thereby depriving herself of a perfect opportunity for needless drama, as the narrator tells us.

* Done in ''TooMuchInformation'', when the two main girls of Ace's UnwantedHarem sees him driving a pretty, blond girl around in his sports-car... it's actually his cousin, whom he's giving a ride to an abortion-clinic so her parents won't find out.
* In ''{{Kevin and Kell}}'', a well-intentioned Kell sets her friend Aby Eyeshine up on a blind date with Rudy's hunting coach, Sam Pardus. Sam and Aby, in accordance with the trope, are brother and sister, but Kell didn't know that (all parties found the whole thing amusing). Sam being disguised as a leopard (while Aby is a house cat) and changing his last name in order to coach the Caliban Academy team despite being domesticated makes it that much harder for Kell to find out.

* Used secondhand in ''{{Bones}}'' where Booth and Brennan saw Sweets' girlfriend in a wedding dress hugging another man, and after some disagreement Brennan told him, made worse by her directly informing him that his girlfriend was engaged to someone else. Luckily for them when he confronted her about it she explained what had actually been happening (her trying on a wedding dress for her cousin, who's the same size), and they... [[IfYOuKnowWhatIMean reconciled]].

* In ''{{Zathura}}'' [[spoiler: When Lisa finds out the astronaut she is attracted to throughout the movie is actually her little brother several years later, she cries, [[BrotherSisterIncest "OMG! And I wanted ta--"]] before an explosion cuts her sentence off. Needless to say, she was {{squick}}ed and befuddled by it all.]]

* ''{{Friends}}'': Rachel is shocked that her boyfriend seems to be cheating on her... only to find that the woman he was hugging was his sister. [[spoiler:Then Rachel goes to their apartment and finds them tickling each other, eating whipped cream from each others' laps (!) and ultimately sharing a bath together. The brother and sister still have the same relationship they did when they were younger; ticklefights, silly slanging matches, and bathing together, but there isn't actually a sexual aspect to their relationship at all.]]\\

* Personal anecdotes are in [[TroperTales/RelativeError Troper Tales]].
* Actor SamuelLJackson was once photographed going to dinner with a much younger woman, which caused some speculation amongst celebrity gossipers. This eventually reached Jackson's ''mother'', who called her son to see if this was true. His response? [[CrowningMomentOfFunny ''"You crazy woman, don't you recognize your own granddaughter?!"'']]

* ''RemingtonSteele'': Steele once saw Laura talking with her brother-in-law and thought she was having an affair. It didn't really help that the brother-in-law kept kissing her on the cheek...

* Played with a lot in ''{{Castle}}'', where Rick says to Beckett more than once things like 'I've got a big date' or that he has a lady to see (which generally makes Beckett jealous) when actually is just talking about Alexis.

* In an episode of TheWeekenders, Tish requests that she just hang out by herself for the upcoming weekend...and the others spy on her, suspecting ulterior motives, and see her hanging out with a boy her age all over town. When they confront her about her 'new friend,' she reveals first of all that it's her cousin Doug, and secondly, she ''had'' planned on being by herself that weekend, but Doug's visit was last-minute and her parents asked her to show her around.

This is somewhat the inverse of, but definitely comparable to, LikeBrotherAndSister. If the characters ''themselves'' don't know, it's IncestIsRelative. Sometimes though, it [[{{BrotherSisterIncest}} happens to be]] [[{{NotWhatItLooksLike}} Exactly What It Looks Like]].

* Used secondhand in ''{{Bones}}'' where Booth and Brennan they saw Sweets' girlfriend in a wedding dress hugging another man, and after some disagreement Brennan told him, made worse by her directly informing him that his girlfriend was engaged to someone else. Luckily for them when he confronted her about it she explained what had actually been happening (her trying on a wedding dress for her cousin, who's the same size), and they... [[IfYOuKnowWhatIMean reconciled]].

* The plot catalyst in ''Grey Matters''. The brother-and-sister team both kiss the same woman, too.

* Early on in ''WithSixYouGetEggroll'', Abby McClure and Jake Ibberson, both widowed with children, make a date for Friday night. Jake calls to cancel, citing his daughter's birthday, so Abby goes to a disco with her sister and brother-in-law, where they see Jake dancing with a pretty young girl. Abby gives Jake the cold shoulder, but later learns that the pretty young girl is actually Jake's daughter when she sees her at her son's high school graduation.

This is somewhat the inverse of, but definitely comparable to, LikeBrotherAndSister. If the characters ''themselves'' don't know, it's IncestIsRelative. Sometimes though, it [[{{BrotherSisterIncest}} happens to be]] [[{{NotWhatItLooksLike}} Exactly What It Looks Like]].

'''Warning: Spoilers Ahead.'''

[[AC:{{Anime}} and {{Manga}}]]

** Not quite, but also in it Harima has a cousin named Itoko. Because the Japanese word for cousin IS itoko, every time he says "My cousin" it SOUNDS like he's saying "My Itoko", as if the two are dating. This causes MASS confusion.
* In ''LoveMonster'', Hiyo assumes that Kurou is flirting with Chiya, but in reality he just found out Chiya is his sister. Later on in the story, a {{squick}}y situation occurs where Chiya does actually try to pursue a relationship with Kurou, which is perfectly acceptable in monster society. Kurou is not interested however.

* Toko and Tsukumo Murasame from ''UragiriWaBokuNoNamaeWoShitteiru'' seem to fit this, even going so far as to sleep in the same bed.

[[AC:ComicBooks]]
* This, along with an extra serving of MistakenForGay, happens to brothers Cyclops and Havok in an issue of ''Comicbook/{{X-Factor}}''.

[[AC:{{Film}}]]
* The plot catalyst in ''GreyMatters''. The brother-and-sister team both kiss the same woman, too.
* ''StarWars VI: Return of the Jedi'': Han briefly fears that Leia's avowed love for Luke puts him out of the picture, and promises not to "get in the way." But having discovered Luke is her brother, Leia is able to reassure him. (Of course, considering how vigorously she kissed Luke in the preceding film, Han's doubts weren't exactly unreasonable.)

[[AC:{{Literature}}]]
* This trope is a great staple of the literature of the 19th Century, as it allows the conflict and drama entailed by (usually) a woman flouting social norms, while still keeping the heroine innocent.
** Jerome K Jerome takes a moment to complain about theatre plays relying on this trope FAR too much.

* In JimButcher's ''TheDresdenFiles'', this becomes a RunningGag after ''Blood Rites'', involving Thomas Raith and [[spoiler:Harry Dresden]], made worse by the fact that 1) they cannot openly reveal their true relationship, and 2) they were sharing the latter's small apartment for an extended period after ''Blood Rites''.
** And 3) Thomas was deliberately pretending to be gay in his public life for completely unrelated reasons. Considering all this together, we should have seen it coming from the paragraph after that "Wizard of Oz" poster on Thomas' wall.

* ''{{North and South}}'' by Elizabeth Gaskell. Similarly, the heroine Margaret Hale's reputation is damaged in the hero's eyes after she is observed saying an intimate goodbye to a young man at a train station, and then lies about it. She cannot reveal that the young man was her brother as he is a wanted man.

* This trope is cheerfully {{lampshade}}d in ''The Wouldbegoods'' by [=~E. Nesbit~=]. The child protagonists are reluctantly trying to reunite their adult friend with his long-lost sweetheart even though they fear this will mean he has less time for them. So they are pleased, rather than scandalised, to find the girl embracing another man. But their relief is short-lived and the narrator reflects, ''"He might have known it was her brother, because in rotten grown-up books if a girl kisses a man in a shrubbery that is not the man you think she's in love with; it always turns out to be a brother.''"
* Sue Townsend's AdrianMole, when aged fifteen, is allowed to witness the birth of his sister because the nurses assume he's actually the baby's father.
* In one of Kathy Reichs' [[{{Bones}} Temperance Brennan]] novels, several other characters mention seeing her boyfriend Ryan going out with a young woman. Its eventually revealed that she is his recently discovered daughter.
* When Richard first sees Charles and Camilla together in Donna Tartt's ''TheSecretHistory'' he assumes they are boyfriend and girlfriend. He later learns that they are twins.
** Even later [[spoiler:he learns that he was [[BrotherSisterIncest still right the first time]]]].

* Averted or subverted in ''NorthangerAbbey'' when the heroine sees her LoveInterest with another woman on his arm and immediately comes to the correct conclusion that it's his sister, thereby depriving herself of a perfect opportunity for needless drama, as the narrator tells us.

[[AC:LiveActionTV]]

* ''{{Friends}}'': Rachel is shocked that her boyfriend seems to be cheating on her... only to find that the woman he was hugging was his sister. [[spoiler:Then Rachel goes to their apartment and finds them tickling each other, eating whipped cream from each others' laps (!) and ultimately sharing a bath together. The brother and sister still have the same relationship they did when they were younger; ticklefights, silly slanging matches, and bathing together, but there isn't actually a sexual aspect to their relationship at all.]]
** ''Friends'' also features sibling Ross and Monica Geller, who in spite of never having on-screen moments that may confuse people, are shocked to learn in the tenth season that they had actually kissed while teenagers (in fact, Ross was Monica's first kiss EVER).

* One episode of ''PowerRangersLightspeedRescue'' had Ms. Fairweather call a famous scientist named Clark to help her build some armour for the Rangers. They get along exceedingly well, and Clark is even given the honor of revealing her first name (Angela) to the audience. Meanwhile, Joel, who was in love with her, is seen getting very, very jealous, and even tries to sabotage one of their 'dates.' Finally, they get attacked by a MonsterOfTheWeek and, seeing Ms. Fairweather's obvious distress when Clark is still in danger, Joel decides [[IWantMyBelovedToBeHappy he wants his beloved to be happy]] and saves his rival. Later, he gamely tells her how glad he is for her and that she deserves the best boyfriend ever. Naturally, this is when he is treated both to the reveal that he was her brother all along and to a kiss on the cheek. In a NoHuggingNoKissing series, even. Joel and Ms. Fairweather have the distinction of being the first PR OfficialCouple to get married.

* The brothers in ''{{Supernatural}}'' are frequently mistaken for a gay couple. This apparently does not stop being funny, ''ever''.
** In the CrapsackWorld of ''{{Supernatural}}'' you have to learn to take what laughs exist when they come.

* Done with Geraldine's love interest in the final episodes of ''{{The Vicar of Dibley}}''.
* When the box containing River is opened in ''{{Firefly}}'' Mal says scornfully, something to the effect of "Is she your lover, because you do seem awfully worried."
** Specifically, he accuses Simon of human trafficking, then sarcastically says something like "Oh, I'm sorry. Is this one for you, is it true love?"

[[AC:{{Theater}}]]

[[AC:WebComics]]

* In ''{{Kevin and Kell}}'', a well-intentioned Kell sets her friend Aby Eyeshine up on a blind date with Rudy's hunting coach, Sam Pardus. Sam and Aby, in accordance with the trope, are brother and sister, but Kell didn't know that (all parties found the whole thing amusing).
** Sam being disguised as a leopard (while Aby is a house cat) and changing his last name in order to coach the Caliban Academy team despite being domesticated makes it that much harder for Kell to find out.
* BadlyDrawnKitties used this once. Lucy overheard Lydia's boyfriend Dirk and another woman declaring their love for each other, and assumed because of the woman's foreign accent that she wasn't related to Dirk. It turned out she was in fact his sister and she'd just been studying in England, and so had picked up the accent;

** Given that Lucy had had a [[BrotherSisterIncest "unique relationship"]] with her own brother, that wasn't actually an unreasonable assumption on her part.
*** But in the original continuity, Lucy and her brother were originally '''from''' Georgia (the US state), so there may have been some LampshadeHanging in the rebuttal.

[[AC:WesternAnimation]]

[[AC:RealLife]]

* Alleged RealLife example: One of the "reader submitted stories" in ''Reader's Digest'' came from someone who claimed to have two single friends he had never seen together, but who had a ridiculous amount of things in common, so he set them up on a blind date. When he introduced them, they immediately displayed a moment of melodramatic mock-romance and then burst out laughing. He said, "Oh, you two already know each other?" The male of the pair replied, "She's my sister, you idiot!"

** A similar example occurred when ex-England football team coach Sven Goran Eriksson was snapped with a young blonde. the Daily Star "[[BritishNewspapers newspaper]]" ran a front page story, basically emphasising the fact that she was young, blonde and worth a few "Phwoar!"s. The girl turned out to be his daughter.
* Reverse example: The titular hostess of the ''Chelsey Lately'' show recalled one vacation where she was able to upgrade to first class when her ''father'' convinced the stewardess that they were a honeymooning couple.

<<|SiblingTropes|>>
<<|TruthInTelevision|>>

This is somewhat the inverse of, but definitely comparable to, LikeBrotherAndSister. If the characters ''themselves'' don't know, it's IncestIsRelative.

* ''{{Friends}}'': Rachel is shocked that her boyfriend seems to be cheating on her... only to find that the woman he was hugging was his sister. [[spoiler:This is subverted by hinting that the brother and sister are [[BrotherSisterIncest incestuous]] when Rachel goes to their apartment and finds them tickling each other, eating whipped cream from each others' laps (!) and ultimately sharing a bath together.]]
** Correction: [[spoiler:The episode doesn't hint that they are incestuous. The point of the episode is that the brother and sister still have the same relationship they did when they were younger; ticklefights, silly slanging matches, bathing together. Never in the episode does it hint that there is any sexual component to their relationship. The bathing together is iffy, sure, but if you view it in the context of their previously seen interactions it does become more innocent. Still icky though....]]