History Main / FamilyRelationshipSwitcheroo

* ''Series/MidsomerMurders'': In "Death and the Divas", it is revealed that when a younger sister had an illegitimate baby, her older married sister registered the baby as hers and raised the girl as her own.

* In the RomanceNovel ''Whisper To Me Of Love'', the hero believes the heroine, Morgana Devlin, to be the illegitimate daughter of Stephen Devlin, the Earl of St. Audrie's, and therefore the illegitimate half-sister of Stephen's son Julian. However, during a meeting with several other key players in the book, on of them insists that she can't be Stephen's child, as he was away traveling when she would have been conceived. They realize that she's the long-lost daughter of Stephen's late brother Andrew and therefore actually Julian's cousin. When Julian goes to confront his father about this. Stephen cruelly informs him that Morgana actually ''is'' his sister--''Julian'' is the illegitimate one, the result of an affair Andrew had with his mother, meaning that the man he thought was his father is actually his uncle.

* In Creator/MadeleineLEngle's ''A Live Coal in the Sea'', one character is raised by his sister and brother-in-law after his mother dies and it turns out that his father [[spoiler:is not his mother's husband]].

* Chris Crutcher did this in two of his stories. In ''Deadline'', [[spoiler:Dallas]] is really the mother of her younger brother; this is kept a secret because [[spoiler:he was the result of being raped by her uncle at a young age.]] In ''Chinese Handcuffs'', [[spoiler:Stacy Ryder's]] younger brother is really her and [[spoiler:Preston's]] son.

* In the backstory of ''Goldfisch'', the recently orphaned Morrey Gibbs met Spencer, a boy who looked exactly like him and had the same birthday. Morrey concluded that Spencer is his twin brother, and that their parents were forced to give up Spencer because they couldn't afford to raise two children. [[spoiler:"Spencer" isn't Morrey's brother but his ''father'', Conrad Gibbs; due to an accident with a life-granted artifact, Conrad [[FountainOfYouth reverted to the same age]] as his son. For a myriad of reasons, Conrad concluded that the best way to stay in his son's life was to live as his brother]].

** In ''Literature/TheWildflowers'' series, [[spoiler:Cat is raised as her sister Geraldine's daughter. She is initially led to believe that she is Geraldine's biological daughter, then her adoptive daughter. It turns out neither is true -- Geraldine's mother gave birth to Cat, and they are half-sisters.]]
** In the ''[[Literature/CutlerSeries Cutler]]'' series by the same author, Lillian discovers that her mother Georgia [[spoiler:is actually her aunt -- Lillian's birth mother was Georgia's sister who died shortly after Lillian was born.]] Later, when Lillian [[spoiler:is raped and gives birth to Charlotte, the family pretends that Georgia is Charlotte's mother too.]]
** Also in the ''Cutler'' series, protagonist Dawn was abducted as a baby and is returned to her real parents, the wealthy Randolph and Laura Sue Cutler. However, it turns out Randolph isn't her father at all -- [[spoiler:Randolph's own father had raped Laura Sue and is Dawn's biological father. Randolph is really her half-brother.]]
** In the ''[[Literature/TheCasteelSeries Casteel]]'' series, Heaven Casteel learns that her supposed step-grandfather is actually her father, thanks to him raping her mother, meaning that she isn't related at all to any of the people that she thought were her siblings. In a later book, her daughter Annie is horrified to find herself developing feelings for her half-brother Luke (the result of her father's drunken one-night with Heaven's "sister" Fanny), only to have it turn out that ''she'' is the result of her mother's own adulterous liaison, meaning she and Luke aren't related at all.
** The ''[[Literature/DollangangerSeries Dollanganger]]'' series reveals that [[spoiler:Chris Sr's mother Alicia was raped by his older half-brother Malcolm, leading to the birth of Corrine. Therefore, while Chris Sr and Corrine married believing themselves to be "only" (half-)uncle and niece, they were in fact ''also'' (half-)brother and sister.]]
** In the ''Literature/LoganSeries'', Melody Logan's mother Haille was raised as the adoptive daughter of Olivia and Samuel Logan, but [[spoiler:her biological mother turns out to be Olivia's sister Belinda.]] This also means that [[spoiler: Melody and Cary are second cousins rather than first cousins, paving the way for them to marry.]]

* An entire [[http://www.fimfiction.net/group/204132/applejack-is-apple-blooms-mother group]] on Website/FimfictionDotNet is dedicated to stories where Applejack is revealed as Apple Bloom's biological mother, but passed her off as her sister. At least one of them also has Big Macintosh as Applejack's [[FlirtyStepsiblings stepbrother]] and Apple Bloom's biological father.

* ''ComicBook/{{Batman}}'': In some incarnations, [[ComicBook/{{Oracle}} Barbara Gordon]] is the niece of Jim Gordon whom he adopted after her biological parents died.

* ''ComicBook/GreenLantern''" Volume three had a "Hard-Traveling Heroes" team-up between the Kyle Rayner Green Lantern and the Connor Hawke ComicBook/GreenArrow to search for Kyle's missing father. They end up meeting a man who claims to be Aaron Rayner and manipulates his alleged son into assisting in a domestic terrorism plot, but turns out to actually be [[EvilUncle Kyle's Uncle Zachary]], [[DeathbedConfession not revealing the truth to his nephew until he's at death's door]].

* ''Series/SaturdayNightLive'' had an "Inside Franchise/{{Barbie}}'s Dreamhouse" [[https://youtu.be/PXUeS2Vg9SE sketch]] in which Barbie (Creator/AmyPoehler) confesses to her "kid sis" Skipper (Music/BritneySpears) that she's actually Skipper's mother, as well as Kelly's and Krissy's mother; their illegitimate fathers include action figures of [[Franchise/StarWars Han Solo]] and two Franchise/PowerRangers.

* Up until the 1970s (when the Pill and legalized abortion became available and cohabitation as well as single parenthood became acceptable), it was common for young women pregnant out of wedlock to be [[StigmaticPregnancyEuphemism "sent away" before they started to show and to give birth in secret.]] "Homes for wayward girls" were essentially private maternity wards where women were heavily pressured to give their children up for adoption (as long as they were white — at the time the adoption prospects for nonwhite babies were... pretty grim). Birth mothers might not even be allowed to ''see'' their babies before they were taken away to their adoptive parents. Faced with losing her child forever, it's not hard to see why a mother might prefer becoming an "older sister" who could still be part of the child's life. ''The Girls Who Went Away'' by Ann Fessler is a good source for those looking to learn more about maternity homes and forced adoption. While many children of young unwed mothers are still raised wholly or partially by their grandparents, it's much less common for families to bother concealing the underlying biological relationships.

* Music/BobbyDarin's mother, Nina Cassotto, was 17 and unmarried when he was born, and he grew up thinking his parents were Nina's parents (even though her father died of pneumonia a year before he was born) and that Nina was his older sister. He didn't learn the truth until he was 32 years old, and the identity of his biological father remained a very closely-guarded secret right up to Nina's death in 1983.

* {{Serial killer}} Ted Bundy suspected for years that his older sister was in fact his mother, finally learning it for a fact in 1969. Even worse, she might very well ''have'' been his sister after all, given the heavy, yet unproven speculation that he was the result of ParentalIncest between her and his grandfather.
* Nobel Prize-winning geneticist Sir Paul Nurse was conceived out of wedlock, and was raised by his grandparents in the belief that they were his real parents and his birth mother was actually his sister. They took the secrets to their graves, and Nurse only discovered the truth in his fifties, upon being appointed president of Rockefeller University; his application for a green card was denied as his birth certificate did not name his parents, and when he applied for a replacement that named them, the truth came out.

%%* Kelly O'Hare, title character of the 1983 (or so) comic ''ComicBook/CuteyBunny'' has a dependent, Taffy; they both have a youthful enough appearance to have characters remark: 'sister, huh...?'
* Volume three of ''ComicBook/GreenLantern'' had a "Hard-Traveling Heroes" team-up between the Kyle Rayner Green Lantern and the Connor Hawke ComicBook/GreenArrow to search for Kyle's missing father. They end up meeting a man who claims to be Aaron Rayner and manipulates his alleged son into assisting in a domestic terrorism plot, but turns out to actually be [[EvilUncle Kyle's Uncle Zachary]], [[DeathbedConfession not revealing the truth to his nephew until he's at death's door]].
* In the ''ComicBook/{{Hellblazer}}'' spinoff comic ''Lady Constantine'', [[spoiler: Johanna Constantine travels with her "little brother" Mouse, who's actually a girl posing as a boy. Johanna's reason for the disguise is that "bad things happen to little girls on the streets of London"... foreshadowing the reveal that Mouse is actually Johanna's daughter, and implying that the pregnancy was the result of rape.]]
* In some incarnations, [[ComicBook/{{Oracle}} Barbara Gordon]] is the niece of Jim Gordon whom he adopted after her biological parents died.
* Subverted in ''ComicBook/{{Transmetropolitan}}''. Not only is the child entirely unwanted when it shows up--it also has ''no head'', which fails to surprise anyone who knows the alleged father. And then it [[spoiler:turns out to be a walking humanoid bomb]].
* ''Comicbook/TroubleMarvelComics'', [[CanonDiscontinuity theoretically]] a romantic ''ComicBook/SpiderMan'' prequel miniseries, infamously made Aunt May the biological mother of Peter Parker. Richard Parker was still his father; in this version, Mary and May were best friends dating two brothers, but May and Richard had an affair. Mary agreed to pretend May's baby was hers, not even telling Richard the truth, and when they died little Peter was passed back to "Aunt" May and Uncle Ben anyway.
* In Wildstorm comics' ''ComicBook/WildCATsWildStorm'' it was revealed that Zealot, who has looked out for her "little sister" Savant since she was born, is actually Savant's mother. (And that Majestic was her father). However the ResetButton was pushed on the entire title the issue after this was revealed, so God only knows if it's still in-continuity.

* In ''ComicBook/XStatix'', U-Go-Girl has a younger "sister", Katie, who is actually her daughter. Katie is told the truth by her mother's ghost in the 2019 relaunch.

* ''Fanfic/ADifferentOutcome'': Exaggerated; in order to distract the other Clans from Hollyleaf announcing she's the offspring of a [=WindClan=] warrior and the [=ThunderClan=] medicine cat, Jayfeather decides to explain in detail how all the cats in [=ThunderClan=] are ''actually'' related to each other using generics to support his claims. Due to the Clan's TangledFamilyTree, this results in a lot of cats learning that their relatives are related to them in ways they didn't think they were.