History Main / NotBloodSiblings

* In ''Literature/MyNextLifeAsAVillainessAllRoutesLeadToDoom'', the Claes family adopts a distant relative, Keith, to become their new heir when it becomes clear that Katarina won't be able to carry on the family name as she is betrothed to the third prince of the country. Within a few days he falls in love with his new big sister and does his best to protect her, but she's [[CaptainOblivious kinda clueless]] and never gets a hint. Keith's new adoptive mother ends up being won over by him and tries to get Katarina's engagement annulled so that Keith can marry her instead, but has no luck. What the Duke did is practically the standard ''[[WeAllLiveInAmerica Japanese]]'' practice in his position, because (as discussed in the Real Life section) in ancient Japan, titles of nobilty are strictly transmitted to sons, and not even first cousins.

* In ''LightNovel/MyNextLifeAsAVillainessAllRoutesLeadToDoom'', the Claes family adopts a distant relative, Keith, to become their new heir when it becomes clear that Katarina won't be able to carry on the family name as she is betrothed to the third prince of the country. Within a few days he falls in love with his new big sister and does his best to protect her, but she's [[CaptainOblivious kinda clueless]] and never gets a hint. Keith's new adoptive mother ends up being won over by him and tries to get Katarina's engagement annulled so that Keith can marry her instead, but has no luck. What the Duke did is practically the standard ''[[WeAllLiveInAmerica Japanese]]'' practice in his position, because (as discussed in the Real Life section) in ancient Japan, titles of nobilty are strictly transmitted to sons, and not even first cousins.

* Played with in Augusten Burroughs' ''Sellevision'' where two main characters fall in love and bang, then find out they are related [[spoiler:but they're actually not... whew]].

* In the ''Hetty Feather'' series by Creator/JacquelineWilson, Hetty's most consistent love interest is her former foster brother Jem. In the final book, ''Emerald Star'', he proposes to her and when she protests that she is his sister, he tries to convince her that they are allowed to love each other because they are not blood relations. [[spoiler:Hetty rejects him anyway as she is leaving to join the circus.]]

* In the young adult novel ''Cluing In'' by Jo Ramsey, main character Jamey Mandel's parents, Tamara and Sam, are stepsiblings; Tamara's father Victor is married to Sam's mother Martha. Somewhat subverted in that Tamara got pregnant with Jamey (at age 17) before she and Sam realized their parents even knew each other, and before Martha got pregnant by Victor. Victor and Martha got married before Tamara and Sam did, though.

* In the Hallmark movie ''What the Deaf Man Heard'', the main character's love interest mentions to him in passing that her {{Jerkass}} brother is the one who revealed to her that she was adopted. Although this is never brought up again, the reason for its inclusion in the script becomes apparent when it comes to light that [[spoiler:the main character is the illegitimate son of her adoptive father, and thus the heir to the family fortune.]]

* ''Simpua'' or ''tongyangxi'' was a tradition of ArrangedMarriage dating back to pre-modern China -- pariuclar Taiwan -- in which a family would adopt a pre-adolescent daughter as a future bride for one of their pre-adolescent sons. The children would be raised together, and then marry when they were old enough.

* Arthur and Morgana in ''Series/{{Merlin|2008}}''. Morgana was raised as the ward of Arthur's father King Uther after her father Gorlois, his best friend, died. No expressed romantic interest on either side, but definite sparks and ShipTease, and Morgana's handmaiden Gwen states that Morgana will surely be queen one day. Then in "The Crystal Cave," it is revealed that [[spoiler:they ''are'' blood siblings, as Uther had an affair with Gorlois's wife]]! Though technically, that's been an ItWasHisSled for several hundred years now.

* In ''Series/NinjaTurtlesTheNextMutation'', it was claimed that none of the Turtles were actually related to each other; they just happened to be the same relative age in the same terrarium at the time. This was done so that there would be the potential for Leonardo, Donatello, Raphael, or Michelangelo to have a relationship with the fifth female turtle Venus de Milo, who was established as having mutated with the other four before being separated from them.

* Zig-zagged in Kelly Link's short story "Valley of the Girls". The main characters are all rich teenagers whose parents have hired them Faces, essentially [[BodyDouble Body Doubles]] who act as their perfectly-behaved public relations stand-ins so that they don't have any embarrassing scandals (the kids themselves have implants which prevent them showing up on video or photographs). The unnamed narrator's Face is in love with his sister Hero's Face [[spoiler:and the narrator recorded them having sex]]. The two only pretend that they're related for public events (although it's been their full-time job for at least eight years, which means they've spent nearly their lives faking siblinghood). But still, in all ways except legally, a Face ''is'' the person they stand in for -- the narrator bitterly notes that his Face makes a better him than he does -- so if anyone ever found out, it would be treated as real incest. [[spoiler:Which is why Hero decides to kill the narrator.]]

* Heathcliff and Catherine Earnshaw in ''Literature/WutheringHeights'' (1847), Heathcliff being a fostered foundling. On the other hand, it's been speculated that (like many "wards" of the era) he might really have been an illegitimate son of Catherine's father, which would make them half-siblings.

For when "siblings" are by choice, instead of blood, that's FamilyOfChoice. Also, do not forget that the ever-growing number of imouto-titles has practically translated this trope into the category LikeYouWouldReallyDoIt and CaptainObviousReveal, so even its well-founded use can very quickly get into ClicheStorm. NotBloodSiblings is to BrotherSisterIncest as FauxInterracialRelationship is to MalignedMixedMarriage. Not to be confused with BloodBrothers, where unrelated characters make a pact and become like siblings. Also see WifeHusbandry for when this trope is taken to an even squick-ier level. For the inverted version -- people who find out they're related after thinking they're not -- see SurpriseIncest.

* ''Anime/CodeGeass'' played with this in one of its many [[AllThereInTheManual Sound Episodes]]. Shirley goes through a series of [[ImagineSpot Imagine Spots]] in which her attempts to ask Lelouch out go spectacularly wrong. In one of the imaginary sequences, his ill little sister Nunnally enters the scene and says that they'll be late for the wedding; as Shirley recoils in shock, the pair claim that they're NotBloodSiblings, so it's okay. In reality, Nunnally and Lelouch are blood-related, though they still have IncestSubtext nevertheless.

* Subverted in ''Manga/IDontLikeYouAtAllBigBrother''. Shuusuke is determined to treat Nao like a sister and nothing else, [[ChivalrousPervert despite him totally having the hots for her.]] Nao, on the other hand, is actually slightly ''disappointed'' to find out that they're NotBloodSiblings, [[CovertPervert because it makes their attraction to each other less taboo.]][[note]]she quickly gets over this when it occurs to her that this means she can openly date and marry him.[[/note]]

* In ''Anime/MagicalGirlLyricalNanohaStrikers'' the [[ShipTease hinted-at]] ToyShip of Erio and Caro may sort of fit this in that Fate ends up being the legal guardian of both (though Erio is technically under the custody of Fate's adoptive mother Lindy due to her having been too young to put her name on the paperwork). The accompanying ''[=StrikerS=]'' manga has them repeatedly state that they are technically adopted siblings... while lathering on even more ShipTease. Unlike other [[NotBloodSiblings non-blood siblings]], they had never met prior to ''[=StrikerS=]'', and had no pre-existing sibling relationships (they even begin on a LastNameBasis).

* The canonical routes in both ''VisualNovel/DaCapo'' games have always been about NotBloodSiblings, though the second game strayed into a fine line between this and KissingCousins for both Asakura sisters, since the protagonist is both adopted ''and'' raised by another parent--who, in turn, is another NotBloodSiblings with Asakura grandpa.

* ''Series/PrettyLittleLiars'': Stepsiblings Jenna Marshall and Toby Cavanaugh.
--->'''Aria:''' Toby and Jenna had a relationship.\\
'''Spencer:''' Way beyond step-siblings.\\
'''Aria:''' Yeah, they… were involved.\\
'''Emily:''' Romantically?\\
'''Spencer:''' I doubt I'd call it ''romantic''--I doubt she had much of a choice.
:: Because AllAbusersAreMale and DoubleStandardRapeFemaleOnMale, it's assumed that Toby was the [[SexualExtortion perpetrator]]. He wasn't.
--->'''Jenna:''' You need to be home. Where you're safe.\\
'''Toby:''' You could chain me to this porch and I'd still never touch you like that again.

* ''Series/TheUmbrellaAcademy'':
** Adopted siblings Allison and Luther are in love, despite having grown up together from infancy. This leads to a clash in tone since the six main characters are ''constantly'' referred to as brothers and sisters, and all consider Reginald and Grace their parents. Later joked about in Season 2, when Klaus makes fun of Allison having to say they're "technically" not related. [[spoiler:Allison ends up getting together with someone else (again).]]
** In Season 2, [[spoiler:Diego]] falls in love with a girl who turns out to be another one of the special children. When he learns of this, he nervously asks the others if they're not biologically related. (This particular superpowered kid was raised by different parents, but genetically it's unclear, considering they're all a case of ExpressDelivery.)

* Played straight in ''LightNovel/OniAi''. Akito and Akiko are apparent twins, and the entire show chronicles Akiko's efforts to get in the pants of her older brother. Only in the last episode is it revealed that Akiko's been, for the sake of his sister, [[spoiler:keeping his adoption a secret all along]].

* ''LightNovel/AscendanceOfABookworm'': After the protagonist gets AdoptedIntoRoyalty (technically nobility), there are a few scenes in which she suspects that her adoptive father is planning to have her marry her adoptive brother.

* On ''WesternAnimation/UglyAmericans,'' [[ZombieAdvocate Mark]] and [[HornyDevil Callie]] raise the latter's younger sister, [[AntiChrist Lillith]] (which admittedly [[RapidAging only took about two weeks]]). Lillith then declared her intention to kill Callie and have sex with Mark in front of a stadium full of other demons. Mark, who had spent the entire episode acting like a doting, enthusiastic father, is understandably freaked out.

** Averted pointedly when Diane meets [[spoiler:Noah]]. He's the adopted son of her biological father who she barely knows. She's still absolutely horrified when he points [[SuggestiveCollision how the way she tackled him looks]], and shudders when Lucy asks if he's an ex-boyfriend of hers.

* Approached from the opposite direction by Grace in ''Webcomic/ElGoonishShive'', who despite being "[[http://www.egscomics.com/comic/2014-07-25 practically]] [[http://egscomics.com/comic/2016-08-01 married]]" to Tedd Verres [[http://egscomics.com/comic/2005-04-27 claims]] Tedd's father as her adoptive father.
* ''Webcomic/ExperimentalComicKotone'' Konstantin seems to think this is going on between Onii-chan and Kotone in ''[[http://www.tsunamichannel.com/index.php?date=2001-11-06&comic=ExCoKo Experimental Comic Kotone]]''. It isn't. What none of the characters except Kotone-chan herself and Onii-chan know is that Kotone is a RobotGirl--the whole "little sister" thing is just a cover.

* ''Completely'' inverted in ''Manga/KoiKaze,'' where Koshiro and Nanoka develop an attraction for each other and then find out they ''are'' blood siblings who haven't seen each other in 10 years. The story revolves around how they cope--or not--with the fact that they can't get over their feelings for each other. In fact, ''Koi Kaze'' uses the [[http://en.wikipedia.org/wiki/Genetic_sexual_attraction documented phenomenon]] of "genetic sexual attraction" as a factor in Koshiro and Nanoka's interactions.

* ''Series/{{Outlander}}'': Marsali and Fergus are Jamie Fraser's stepdaughter and adopted son who both consider Jamie their father figure. However, they lived with Jamie nearly a decade apart and weren't raised in the same household or as siblings, so they don't see each other as brother and sister. But given that this is a time period where first cousins marry with no controversy, stepsiblings with no blood relation probably wouldn't raise any eyebrows.

* ''Series/{{Outlander}}'': Marsali and Fergus are Jamie Fraser's stepdaughter and adopted son who both consider Jamie their father figure. However, they lived with Jamie nearly a decade apart and weren't raised in the same household or as siblings, so they don't see each other as brother and sister. But given that this is a time period where first cousins still marry with no controversy, stepsiblings with no blood relation probably wouldn't raise any eyebrows.

* ''Series/{{Outlander}}'': Marsali and Fergus are Jamie Fraser's stepdaughter and adopted son who both consider Jamie their father figure. However, they lived with Jamie nearly a decade apart and weren't raised in the same household or as siblings, so they don't see each other as brother and sisters. But given that this is a time period were first cousins marry with no controversy, step siblings with no blood relation probably wouldn't raise any eyebrows.

* Subverted for all it's worth on ''Series/ArrestedDevelopment''. [[spoiler:Cousins George Michael and Maeby are attracted to each other and George Michael clings to any hope that Maeby isn't his Aunt Lindsay's daughter. When they find out that there's a chance she's been adopted, they go to second base... then they find out that she ''is'' Lindsay's daughter. As a result, Maeby begins dating a boy from school--Steve Holt. Meanwhile, Steve decides to find the father he never knew, who turns out to be GOB, Maeby's uncle. As a result, they break up. Then, Maeby's mother Lindsay turns out to be adopted. Lindsay promptly starts hitting on George Michael's father, who is completely freaked out after thinking she was his twin for 37 years.]] [[spoiler:And then, "in a kneejerk act of revenge", Michael's brother GOB decides to hit on his adoptive sister Lindsay.]] [[spoiler:Subverted again in the GrandFinale with the reveal that Lindsey actually is Lucille's much younger half-sister, making all these examples 100% incestuous--Lindsey is GOB and Michael's half-aunt, while George Michael and Maeby are half-first cousins once removed.]]

* Subverted for all it's worth on ''Series/ArrestedDevelopment''. [[spoiler:Cousins George Michael and Maeby are attracted to each other and George Michael clings to any hope that Maeby isn't his Aunt Lindsay's daughter. When they find out that there's a chance she's been adopted, they go to second base... then they find out that she ''is'' Lindsay's daughter. As a result, Maeby begins dating a boy from school--Steve Holt. Meanwhile, Steve decides to find the father he never knew, who turns out to be GOB, Maeby's uncle. As a result, they break up. Then Maeby's mother Lindsay turns out to be adopted. Lindsay promptly starts hitting on George Michael's father, who is completely freaked out after thinking she was his twin for 37 years.]] [[spoiler:And then, "in a kneejerk act of revenge", Michael's brother GOB decides to hit on his adoptive sister Lindsay.]] [[spoiler:Subverted again in the GrandFinale with the reveal that Lindsey actually is Lucille's younger half-sister. Making all these examples 100% incestuous.]]