-->"My parents won't buy me a dog."\\
"How did you ask them?"\\
"I asked, 'Mum and Dad, can I have a dog?'"\\
"That's the wrong way. You have to ask, 'Mum and Dad, can I have a baby brother?"

Siblings. Lots of us have 'em. Lots of us don't. The latter situation is [[OnlyChildSyndrome often quite common in fiction]], leading to a lot of only children running around.

But some fictional only kids (especially younger ones) are not happy with the situation. Maybe they're lonely because they have no one to play with. Maybe they're frustrated because they have [[BigBrotherBully no one to push around.]] Maybe they just see a lot of other kids with siblings in real life and are just jealous. Whatever way, they know what they really want: A younger sibling. And they aren't afraid to ask their parents for one.

Their parents are generally less thrilled about this, because even if they ''also'' want another child, they're not keen on [[TheTalk telling their kid where said baby is going to come from.]]

Frequently, kids will express a desire for a sibling the same gender as them: Girls generally want little sisters, and boys typically want little brothers. But the opposite situation isn't unknown: Sometimes boys want little sisters in an attempt to purposefully invoke BigBrotherInstinct. Similarly, sometimes tomboyish girls will want brothers... and not-so-tomboyish ones want [[DraggedIntoDrag living dolls]].

In works with a fantastic bent, this may be a cue for a younger sibling to suddenly come into the picture through [[WonderChild supernatural or superscience-y means.]] In less-fantastic works, it's often up in the air whether the kid gets their sibling or not. Nor is there any guarantee that, should they get their wish, they and their new sibling will [[SiblingRivalry get along the way the older one dreamed]].

Compare IWantGrandkids (for when it's the parents' parents doing the pushing). This is also TruthInTelevision, which is probably why it shows up often enough.

[[AC:{{Anime}} and {{Manga}}]]
* ''ChocottoSister'' is about a boy who always wanted to be an older brother, but who never got a younger sibling... until one day, in his college years, SantaClaus gives him a little sister for Christmas.
* In ''NanohaTheMovieFirst'', it is revealed that Alicia Testarossa always wanted a little sister (which is exactly what Fate is to her), as Presea remembers [[spoiler:only while plummeting to her death]].
* In ''LightNovel/{{Baccano}}'', Isaac and Miria receive a letter from Ennis that mentions her sadness over her "brothers created before her, who [she] never got to meet." They assume she's asking them for a baby brother. [[spoiler:[[ImTakingHerHomeWithMe And so they bring home Czeslaw.]]]]

* From Webcomic/KillLaKillAU, Nui wanted another little sister and she got one, making that played straight. However, this is justifiably averted with Satsuki, having to live with Ryuuko and Nui.

* In the film ''Film/TheHuntForRedOctober'', Jack Ryan tells his CIA boss that his daughter ("a very precocious five") asked him and his wife to "''buy'' her a baby brother" and settled for them buying one for Stanley (her teddy bear) instead. At the close of the film, Ryan is shown sleeping on his flight home with a teddy bear in the next seat.
* At the end of the remake of ''MiracleOn34thStreet'', Susan remarks to her mother that her Christmas wishes were a house (instead of their trendy apartment), a dad, and a baby brother. [[spoiler:Since her mother marries her longtime boyfriend on Christmas Eve, and Christmas morning finds them moving into Susan's dream home, it's heavily implied that the mother is pregnant.]]

* In ''TheDresdenFiles'' short story ''It's My Birthday Too'', Harry reveals that he wished for a brother when he was a child in the orphanage after his father's death. Ironically (and heartwarmingly), the person he's telling this story to is [[spoiler:his long-lost and recently found older brother Thomas]].
* One adventure of Literature/TheBabySittersClub has Mary Anne and Dawn wanting their parents to have a baby so they'll be able to baby-sit it. They come to their senses by the end of the book.

* The seventh edition of annual Dutch children's choir project ''Kinderen voor Kinderen'' included a song called "Ik ben toch zeker Sinterklaas niet" (roughly, "Do I look like Santa Claus?"). The lyrics kick off with little Sascha's wish list: a baby brother, and a pretty red bike, and a giant teddy bear, in that order.

* In ''ComicStrip/CalvinAndHobbes'', Calvin once tells his mother he wishes he had a little brother. "You want a new friend to play with?" "No, I just want somebody small I could beat up." [[http://www.gocomics.com/calvinandhobbes/1992/10/07 The next panel is Calvin's dad at work telling his wife they'll talk about that operation later]].
** Subverted later when Calvin's Mom is sick, Hobbes suggests she might be pregnant, and Calvin panics.

* ''Tomorrow, the World!'' by James Gow and Arnaud d'Usseau:
-->'''Michael''': Pat worships you. She comes home from school every day telling me you're the only teacher who has any sense. What's more, she's asked me to get married. To almost anybody! She wants me to have more children. Three of them, to quote precisely.\\
'''Leona''': Mike!\\
'''Michael''': As soon as we're married, I'm sure she'll take it up with you.

* Many of the "rival children" in ''HarvestMoon: Animal Parade'' express a desire for younger siblings, but the two who fit the trope most closely are Lucy and Dakota. Lucy asked her parents, and they agreed, but never have any luck having a second because StatusQuoIsGod. Dakota, meanwhile, went ''[[PluckyGirl all the way to the]] [[{{God}} Harvest King]]'' to ask for a little sister, but he told her there was nothing he could do unless [[NoAccountingForTaste her parents started getting along first]].
* In ''VideoGame/FireEmblemAwakening'', if Yarne is paired up with his father and steps on an event tile, the latter will ask if the former wants something. Yarne asks for "lots of bunny-eared brothers and sisters". This is completely justified, as Yarne's greatest fear [[spoiler:(having come from a BadFuture where his mother died) is [[LastOfHisKind the extinction of his kind]].]]

* In ''{{Drowtales}}'', it's considered good luck to have twins or a similar - age sibling. As a result, the Sharen clan has the practice of a "protector twin" (adopting - or buying - a child, usually from a servant family) to give their own children a chance to have a same - age sibling. Unfortunately, this often results in sibling rivalry, ending with the death of the protector twin at the hands of the former child, or (less often) vice versa.
* In ''SomethingPositive,'' [[BrattyHalfPint Rory]] decides he wants a little sister; his mom doesn't seem interested, but when his ParentalSubstitute [[JerkWithAHeartOfGold Davan]] gets engaged he immediately starts suggests he get his fiancée, [[TokenWholesome Vanessa]], pregnant. Vanessa, who doesn't want kids, agrees as long as Rory is present at all her births--[[ScareEmStraight then shows him a video]] of what [[{{Squick}} the birthing process looks like]].

* ChakonaSpace has examples of Chakat cubs asking their parents to get busy giving them a little sister.

* One episode of ''WesternAnimation/TheAdventuresOfJimmyNeutron'' involved the title character asking his parents for a little brother. Since they politely declined, he used his [[ChildProdigy mad science]] to make a ''robotic'' little brother named Brobot. Brobot [[StatusQuoIsGod didn't stick around on Earth]], but ''did'' become a minor recurring character.
* One episode of ''{{Rugrats}}'' involved Tommy really wanting a little brother. [[ItMakesSenseInContext He then thinks that a bird's egg is his little brother Milton.]] The egg was just a baby bird, but he ''did'' get a real little brother named Dil after TheRevival.
* The OhYeahCartoons short ''Zoey's Zoo'' involves a little girl who keeps tons of animals in her own personal "zoo," because her parents (or at least her mother, whom we only ever see) never caved in to her desire for a little brother. Doesn't stop her from asking about it incessantly, though.
* Littlefoot in at least one of the ''TheLandBeforeTime'' sequels has shown interest in wanting a sibling. It doesn't help that he's one of the only main characters in the entire series (except for Chomper) to be an only child. He DID get a stepbrother when his long-absent father Bron returned in the tenth film, and at Littlefoot's urging, adopted Shorty, a brachiosaurus who had come to view Bron as a father.
* Once on ''TheSimpsons'' Bart, upset about being the OutNumberedSibling, tries to trick his parents into having another baby. Eventually Marge confronts him about what's going on and explains that she and Homer only wanted 3 kids, and even if they ''did'' have another baby, it might be a girl. Bart winds up going to the orphanage and temporarily adopting a brother instead.
* ZigZagged in the ''FamilyGuy'' episode "Emission Impossible": first is inverted when Stewie hears that Peter and Lois want another kid, and he tries to sabotage any of their attempt at having sex. After meeting one of his possible future siblings inside Peter's testicles ([[ItMakesSenseInContext long story]]), he's eager to have a younger sibling. However, he later changed his mind again.