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[[quoteright:300:[[WesternAnimation/TheFlintstones http://static.tvtropes.org/pmwiki/pub/images/unto-us-a-son-and-daughter-are-born2_8580.jpg]]]]
[[caption-width-right:300:[[PinkGirlBlueBoy Color-coded for your convenience.]]]]

->''You will be having both a boy and a girl.''
-->-- '''Dr. David Shaw''', ''[[http://www.fanfiction.net/s/5133787/1/LIFE-S-LITTLE-JOY Life's Little Joy]]''

Twin characters in a work of modern fiction come in all sorts (though they have a [[AlwaysIdenticalTwins disproportionate tendency to be identical]]). However, when twins are ''born'' over the course of the story (as part of a BabiesEverAfter or otherwise), they are almost always male and female fraternal twins. This is the most common twin pairing in RealLife (Identical twins ''always'' are, of course; applying this trope to a [[HalfIdenticalTwins pair of identical twins]] is a CriticalResearchFailure.)

Why does this happen? The birth of a boy and a girl instantly creates a fully formed family of father, mother, son, and daughter, putting all of the family relationship tropes into play, without any perceived bias by making the boy or girl older and in an authority position over the other. These twins are frequently the first and only children of their parents. Compared to other twins in fiction, it's more rare for these twin pairs to include an EvilTwin or be SeparatedAtBirth. While they are occasionally HalfIdenticalTwins, more frequently [[GenderEqualsBreed one resembles the mother and the other the father]].

This trope is less prominent in [[OralTradition mythology]] due to the blurred lines between story and backstory. In ancient myths or works like the ''Literature/TheSilmarillion'' that are deliberately mythological, the birth of twin brothers is much more common. The birth of twin sisters is generally rare in all media.

Especially common for firstborn twins in a small NuclearFamily. If twins are born into a large family that already has more than one child of the other gender, this trope is more likely to be averted. When this trope is averted for other reasons it's a very bad sign, as one or both of the resulting children will usually be [[GooGooGodlike supernatural]] or [[EnfantTerrible evil]]. Mythological aversions tend to have different fathers or be destined to depose or kill each other. Aversions are usually still fraternal, though. It's rare to see infant identical twins in fiction, as they tend to appear fully formed at ages six to thirty.

A frequent trope in SoapOpera, although due to the sheer volume of twins in decades-long soaps this is also occasionally averted.

If the parents are the main characters and the twins are infants, it's UntoUsASonAndDaughterAreBorn. If the twins are the main characters and the parents gave birth to them offscreen in the past, it's not. Childbirth scenes are usual but not absolutely required as long as the pregnancy and the twins as small infants are both shown.

Frequently combined with SpinOffspring. Contrast SeparatedAtBirth, which is a backstory trope for older twin characters.

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!!Examples:

[[foldercontrol]]

[[folder:Anime and Manga]]
* ''{{Basara}}'': Tatara and Sarasa.
* In the manga adaptation of {{mothy}}'s [[{{Vocaloid}} ''Aku no Meshitsukai'']], the first chapter opens with the birth of the king's opposite-sex twins. This turns out to be a curse rather than a blessing, as [[spoiler:[[YouHaveOutlivedYourUsefulness before he was killed by the king]], the fortune teller makes one last prophecy that the king's child will be born with a birthmark, a sign that he or she will bring the country to ruin. The queen ends up having twins, and it's the boy who gets the birthmark. The king orders that the prince be [[GirlInTheTower locked in a tower and kept there]].]]
* ''SamuraiHighSchool'': Kou and Tsukiko were newborns at the beginning of the manga.
[[/folder]]

[[folder:Comic Books]]
* ''ComicBook/ElfQuest'': [[http://www.elfquest.com/gallery/OnlineComics/OQ/OQ06/DisplayOQ06.html?page=8 Suntop and Ember]].
** However, in early draft pages they were both boys.
* ''ComicBook/TheFlash'': The Tornado Twins, Don and Dawn Allen.
** And then Wally's kids, Iris and Jai West.
* MarvelUniverse: {{Magneto}}'s twins. Probably lots of others. Averted slightly with the Scarlet Witch's semi-imaginary [[EnfantTerrible evil demon twin boys]].
** At the time the twins were born (at which point they were not yet retconned as imaginary) the writer explained in an interview that he made them same-sex specifically to avert this trope.
* ''{{Spider-Man}}'': NormanOsborn's twins with Gwen Stacy.
* ''ComicBook/{{Spawn}}'': Wanda's twins.
* ''{{Archie}} Gets Married'': Archie and Veronica have twins -- Little Archie and Little Veronica. In the "Betty" version, the same thing happens, with Little Betty instead. Both are a case of GenerationXerox as well.
* Another ''{{Archie}}'' example; [[ComicBook/SonicTheHedgehog Archie's Sonic the Hedgehog]] has been shown having children with Princess Sally in a few alternate futures, and those children are always twins; a girl that resembles her mother, and a son resembling his father.
[[/folder]]

[[folder:Fan Fiction]]
* Generally common in most {{Kid Fic}}s.
* Jillian's children Tilly and CJ from ''[[MegsFamilySeries Meg's Boyfriend]]''.
* Also, Jillian's children Kyle and Maya from ''TheSpellbook''.
* Happens in the final arc of the FanFic/ElementalChessTrilogy (''Manga/FullmetalAlchemist''). Played with in that when someone asks "Did she have a boy or a girl?" the answer comes back "No!"
* Stories where Raven from the ''ComicBook/TeenTitans'' ends up pregnant usually have her end up having a daughter or one of each.
* The Warden and the Mistress's children Ajax and Adele in the ''{{Superjail}}'' fanfic ''[[http://www.fanfiction.net/s/7955447/1/The-Story-Of-Us The Story of Us]]''.
* Also, the Warden and the Mistress's first children Matilda and Ethan near the end of the ''{{Superjail}}'' fanfic ''Fanfic/ExtendedStay''. [[GenderEqualsBreed The girl looks like her mother and the boy looks like his father.]]
* [[WesternAnimation/TheSecretShow Victor and Anita]] give birth to [[ThemeTwinNaming Victor Jr. and Vanessa]] at the end of ''[[http://www.fanfiction.net/s/5133787/1/LIFE-S-LITTLE-JOY Life's Little Joy]]''.
* A common occurrence in Naruto fanfics, with Naruto often having a red-haired fraternal twin sister. The sister often enjoys ParentalFavoritism while Naruto is TheUnfavorite.
[[/folder]]

[[folder: Fairy tale]]
* The First editon of the Grimm Brothers' Rapunzel has twins. The original (kind of) Sleeping Beauty: Taila, Sun, Moon also has twins.
[[/folder]]

[[folder:Films -- Animated]]
* ''Disney/{{Bambi}}'': Geno and Gurri. Well, okay, they're deer. But still.
* ''WesternAnimation/RockADoodle'': Chanticleer and Goldie's son and daughter.
[[/folder]]

[[folder:Films -- Live-Action]]
* Henry and Samantha Focker in ''Little Fockers'', although their actual birth is never depicted.
* Luke and Leia at the end of the ''Franchise/StarWars'' prequel trilogy.
* A major plot point in ''Film/WhaleRider''. The boy was supposed to be the chief of his tribe, but he died soon after being born, leaving the sister with the weight of her grandfather's expectations.
[[/folder]]

[[folder:Literature]]
* ''Literature/{{Animorphs}}'': Darwin and Madra, the children (sort of) of [[spoiler:Visser One]].
* Possibly averted in the ''{{Belgariad}}'' with Polgara's twins, although since they're deliberately nameless and genderless it's really hard to say.
* ''Literature/{{Dune}}'': Leto II and Ghanima. This one also subverts the usually-unplayed {{Twincest}} angle: Leto marries Ghanima, but it's for political purposes. It's not like he could have sex with her or anyone else for that matter anyway; his blending with the sandtrout made that impossible. Ghanima's children are actually and not-so-secretly fathered by Prince Farad'n Corrino, grandson of former Emperor Shaddam IV.
* O-Lan's twins in ''The Good Earth'' by Pearl S. Buck.
* ''Literature/HonorHarrington'': Honor's siblings Faith and James.
* ''Literature/LittleWomen'': Meg is the first of the sisters to marry and have babies, and not only does she have male and female twins, [[GenerationXerox she names them after their parents]]. To adhere to the OneSteveLimit, they go by nicknames: Demi (for Demi-John, "half-John") and Daisy (Margaret = Marguerite = "daisy" in French).
* ''[[TowerAndTheHive Pegasus in Flight]]'': Tirla's twins, Mischa and Miriam.
* Literature/{{Petaybee}}: Ronan and Murel.
* Occurs at the end of ''A Pirate's Pleasure'' by Heather Graham.
* Literature/VorkosiganSaga: Aral and Helen. Perhaps not technically twins, but the same parents and born at the same time. (See UterineReplicator for the ItMakesSenseInContext on ''that'' distinction).
* Literature/TheBobbseyTwins: two sets -- Bert and Nan are the older pair, Freddie and Flossie the younger. They're even ColorCodedCharacters: Bert and Nan are both dark-haired, [[ThemeTwinNaming Freddie and Flossie]] are both blond.
* In Literature/TheThrawnTrilogy, Leia gives birth to Jacen and Jaina; in DarkEmpire she had another boy, [[DeadGuyJunior Anakin]]. During the Literature/NewJediOrder, it was found that the ScaryDogmaticAliens have superstitions about twins, so Shmi Skywalker's surviving descendants were able to take advantage of that. Tellingly, Anakin, the only single birth in the clan, was the only one who died there.
* [[spoiler: Ramses and Nefret]] eventually have a son and daughter in the AmeliaPeabody [[MysteryLiterature Mysteries]].
* In the WomenOfTheOtherworld series, the only female werewolf eventually gets pregnant, though this doesn't stop her from [[PregnantBadass battling bad guys]]. When she finally gives birth, her children turn out to be a boy and a girl, and they're both werewolves (usually only sons inherit the trait).
* Averted in the ''Literature/ArtemisFowl'' series; at the end of ''The Lost Colony'' Artemis [[spoiler: time-skips ahead three years]] and finds on his return that his parents have had twins, but in ''The Time Paradox'' we find out that the twins are both boys.
* In ''Literature/TheWheelOfTime'' series, one of Min's viewings says [[spoiler: Elayne]]'s pregnancy will result in twins, a daughter and a son. As of ''The Towers of Midnight'' Min's viewings have never yet been wrong, so this trope will almost certainly come to pass. In an interesting mythological twist, one "[[FanNickname loony theory]]" is that they will be the reincarnation of the twin Heroes of the Horn Shivan and Calian, whose coming [[TheEndOfTheWorldAsWeKnowIt heralds the end of an Age]].
** The same viewing, and a vision of the future in Rhuidean, also show that [[spoiler:Aviendha]] will get a double dose of this trope: fraternal quadruplets, two sons and two daughters.
* An interesting version in Sheri Tepper's Sideshow involves identical, conjoined twins who are hermaphrodites, but dressed as male and female in order to fulfil their parents' desire for this trope.
* ''Literature/MemorySorrowAndThorn'': Deornoth and Derra, Josua and Vorzheva's children.
* Naturally this happens from time to time in the ''Literature/WarriorCats'' series, since having more than one kitten in a litter isn't out of the ordinary for cats.
* Varencienne gives birth to twins Rav and Elly in ''Literature/ChroniclesOfMagravandias''. The boy looks very like her and the girl like the father. Played with in that Varencienne hated being pregnant and giving birth and had no intention of having more children unless she [[HeirClubForMen didn't have a boy]].
* Dhattar and Aiony in ''Literature/TheFirebringerTrilogy''.
* In ''Sarum'', a Neolithic chieftain's decades-long efforts to produce an heir eventually result in this trope. The "instant NuclearFamily" aspect is subverted, as a prophecy dictates that the daughter immediately be sacrificed at Stonehenge.
* ''Literature/SeerOfSevenwaters'': Cathal and Clodagh's twins.
* The pregnancy that gives Lanen so much trouble in Literature/TalesOfKolmar is a set of twins like this.
* In the ''Literature/HeraldsOfValdemar'' series, after Queen Selenay and Prince Daren marry, they have twins, Kris and Lyra.
* [[ThemeTwinNaming Alianne and Alan]], Alanna's twins in the Literature/TortallUniverse, although they do have a brother who came first and alone (and is named Thom after Alanna's own HalfIdenticalTwin). Alianne grows up to have triplets: two girls and a boy.
* In ''Literature/TheWonderSpot'', Sophie's brother's twins are a boy and a girl.
* The Newman twins Josh and Sophie from ''Literature/TheSecretsOfTheImmortalNicholasFlamel'' series. One has the rare gold aura while the other has the equally rare silver aura. Of course they are the twins of legend. This gets shot to '''hell''' in the final book with TheReveal [[spoiler: they're not twins and not even related. Their parents found Josh during prehistoric times while Sophie was found on the Steppes of Russia. They were raised as brother and sister]].
[[/folder]]

[[folder:Live Action TV]]
* ''Series/AsTheWorldTurns'' had a double version of this with Jeff and Carol Ward's quadruplets.
* ''Series/BrothersAndSisters'': Tommy and Julia's twins, though one died.
* ''Series/CoronationStreet'': Kenneth Barlow's twins, Judy Mallett's twins, Sunita Alahan's twins.
* ''Series/TheCosbyShow'': Nelson and Winnie (Sondra and Elvin's children)
* ''Series/DaysOfOurLives'': Sami and Eric Brady. Sami later gave birth to another set. And that's not even counting her twin siblings who were found in a meteor shower.
* ''A Country Practice'': Simon and Vicky had twins, Tom and Charlotte
* ''Series/EastEnders'': Peter and Lucy Beale, Pete Beale and Pauline Fowler.
* ''Series/{{Emmerdale}}'': Cathy and Heath Hope.
* ''Series/{{Friends}}'': [[spoiler:Monica and Chandler's adopted twins in the final episode.]]
** Averted a few seasons earlier where Chandler imagined a family with twins but they were both girls in addition to two sons that wouldn't be twins.
* Averted in ''Series/FullHouse'', as Jessie & Becky's twins were both boys. Presumably the Olsens had the girl twin side covered, though they only played a single character.
* ''Series/GetSmart'': Max and 99's twins.
* Averted in ''Series/GuidingLight'', with Blake's twin boys, who were briefly thought to have different fathers.
* ''Series/OneLifeToLive'' had this happen in the seventies with Larry Wolek and Meredith Lord's twins, though one was stillborn.
** Also happened in the 90's with Max and Luna's twins.
* Averted in ''SeventhHeaven'' with Sam and David, the youngest of a large family.
** Also averted with [[spoiler:the three sets of twin grandchildren - Matt fathered twin boys, Mary gave birth to twin girls, and Lucy miscarried twin boys]].
* ''Series/TheWestWing'': Toby's twins, Huck and Molly.
* Played straight on ''Series/LittleHouseOnThePrairie'' when Nellie gives birth to twins. It's especially contrived since she and her Jewish husband had agreed beforehand if the baby was a boy, he'd be raised Jewish; if a girl, Christian.
* ''Series/TheNanny'': [[spoiler: Fran and Maxwell's son and daughter]] at the end of the series.
* Averted on ''Series/{{ER}}'' with Doug and Carol's twins, which were both girls. Interesting, since the previous season, the audience had gotten a pretty strong hint that this trope would have been played straight (a psychic patient who claimed to be able to see inside people was trying to decipher if Carol was having a boy or a girl. Her expression seemed to indicate that it was both).
* On ''Series/ThirtyRock'', when Liz and Criss adopt twins, they're a boy and a girl. It turns out that the boy is a miniature Tracy and the girl is a miniature Jenna, meaning [[OnlySaneEmployee Liz's job has actually been perfect practice for raising them]].
[[/folder]]

[[folder:Music]]
* Collin Raye's "One Boy, One Girl".
* There are probably many [=PVs=] for [[{{Vocaloid}} "Servant of Evil"]] that show the twins as infants, but [[http://www.youtube.com/watch?v=Av04XfLtAcU&feature=related this]] version for the classical remix is arguably the best known.
[[/folder]]

[[folder:{{Mythology}} and {{Religion}}]]
* Though not in Literature/TheBible, some Jewish sources say that each of Jacob's twelve sons was born with a twin sister. The same with CainAndAbel.
* ClassicalMythology: Apollo and Artemis. A weird variant is Leda's quadruplets: Castor, Polydeuces, Clytemnestra and Helen.
** Where according to the most popular version Helen and Polydeuces were fathered by Zeus, and Castor and Clytemnestra by Leda's husband Tyndareus. [[WhaleEgg From eggs]], one for the brothers and one for the sisters. You see, Zeus had mated with Leda in the form of a swan and...you know what, this is Greek Mythology. Things aren't supposed to make sense.
* EgyptianMythology: In some myth variants Osiris and Isis are twins.
* NorseMythology: Freyr and Freyja. Borgny gives birth to a set in the Elder Edda.
[[/folder]]

[[folder:Radio]]
* ''Radio/TheArchers'': Lily and Freddie Pargetter, Shula and Kenton Archer.
[[/folder]]

[[folder:Theatre]]
* In the third act of ''Abie's Irish Rose'', Solomon and Patrick, though still angry at each other, are eager to see Abie and Rose Mary's new baby. Solomon wants it to be a boy like his son Abie, and Patrick is eager for it to be a girl like his daughter Rose Mary. It conveniently turns out to be both, so the feud can easily be settled.
* In ''Theatre/OfTheeISing'', after the First Lady saves her husband from impeachment by announcing that he's about to be a father, the question on everyone's minds is: Will it be a boy or a girl? The answer, as decided by the Supreme Court: Both!
-->'''Wintergreen''': That makes me a father and a mother. Twins! That's a little more than I counted on!
* In ''Theatre/DreamGirl'', when Georgina hears about her sister Miriam's pregnancy, she dreams of switching places with her and giving birth to twins which she names Gerald and Geraldine.
[[/folder]]

[[folder:Video Games]]
* ''VideoGame/DragonQuestV'': [[HelloInsertNameHere You get to name both children]]. After all, they're TheHero's and his [[TitleDrop Heavenly Bride's]] kids.
* ''VideoGame/PhantasyStarIII'' has an example of this in [[MultipleEndings one of the third generation scenarios]], as the twins Adan and Gwyn are born if Nial choses [[LoveTriangle Laya as his bride instead of Alair]].
* ''VideoGame/KingsQuest'': King Graham and Queen Valanice sire Prince Alexander and Princess Rosella.
* ''VideoGame/HarvestMoon: Connect to a New World/Story of Seasons:'' For the first time in the series, the children of the main character are twins. Naturally, they're a boy and girl.
[[/folder]]

[[folder:Webcomics]]
* ''Webcomic/CogaSuro'': Towards the end of the first run, twins John and Mary are born.
[[/folder]]

[[folder:Western Animation]]
* ''WesternAnimation/TheFlintstones'': Grandchildren Chip and Roxy. The daughter looks like her father and the son looks like his mother; see the page pic.
* ''WesternAnimation/MyLittlePonyFriendshipIsMagic'': Pound and Pumpkin Cake to Mr. and Mrs. Cake.
[[/folder]]

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