History Main / MistakenAge

* [[Series/HouseMD House]] mistook a 37-year-old patient to be at least 10 years younger than she actually was, which turns out to be a clue for her illness. [[spoiler:She has 'pretty leprasy', a form of leprasy that ended up making her look better, instead of making her skin fester and rot off.]]

* ''Manhwa/TheMonsterDuchessAndContractPrincess'': Characters frequently mistake twelve year-old Leslie for being about nine or ten, as she is smaller and skinnier than she should be for her age due to her abusive upbringing including not feeding her properly. This is exaggerated when she meets Bethrion. Between his only frame of reference being his younger brother and the fact that his family are all naturally large people, he initially assumes Leslie is ''five''.

* [[Wrestling/EddieGuerrero Eddie]] and [[Wrestling/ChavoGuerreroJr Chavo (Jr.) Guererro]] were close enough in age to be brothers (2 years apart), but they were [[WrestlingFamily uncle and nephew]].

* In ''Anime/DennouCoil'' Haraken's aunt, who is referred to offhand as being the commander of the Satchiis, is assumed by the main characters to be at the very least middle-aged. When she finally appears, it turns out that she's actually on the nearer side of twenty.

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* WebVideo/ContraPoints will sometimes {{Squee}} about taxi drivers asking her about college, meaning they think she's young enough to be a student. She's in her early thirties.

* In ''Webcomic/ElGoonishShive'', Amanda exploits [[https://www.egscomics.com/egsnp/2004-08-31 having drunk a soda]] with a FountainOfYouth formula by [[https://www.egscomics.com/sketchbook/2004-09-05 going up to an age guessing booth]].

* In ''Webcomic/TowerOfGod'' this happens commonly since the Shinsoo atmosphere slows down and sommetimes even stops aging. This leads to cases of Shibisu being in his late twenties and Yeon and Hatz in their late teens whereas Endorsi is about 300 years old and her "niece" Anaak is even older.

* In ''Webcomic/TowerOfGod'' this happens commonly since the Shinsoo atmosphere slows down and sommetimes even stops aging. This leads to cases of Ship Leesoo being in his late twenties and Yeon and Hatsu in their late teens whereas Androssi is about 300 years old and her "niece" Anak is even older.

* Comes up in an episode of ''WesternAnimation/FamilyGuy'', where Quagmire (who else?) meets a girl at Peter's party and sleeps with her, thinking she is 18, only to find out that she is 16.

A common one is an aunt. In many cultures aunts are thought of as old, so when the aunt turns out to be only a few years older than the niece/nephew, it can be quite a surprise.

Compare TomboyishName, ExpectingSomeoneTaller, ActuallyThatsMyAssistant, OlderThanTheyLook, YoungerThanTheyLook, ReallySevenHundredYearsOld, and AgeInappropriateDress.

* ''Manhwa/TheMonsterDuchessAndContractPrincess'': Characters frequently mistake twelve year-old Leslie for being about nine or ten, as her abusive upbringing included not feeding her properly, making her smaller and skinnier than she should be for her age. This is exaggerated when she meets Bethrion. Between his only frame of reference being his younger brother and the fact that his family are all naturally large people, he initially assumes Leslie is ''five''.

* In the ''Splatoon'' fic ''Fanfic/HerFracturedSpirit'', Callie is older than Marie. Everyone thinks it's the other way around because Marie is so mature and aloof while Callie is so free-spirited and exuberant.

* In ''Literature/PatienceAndSarah'', Patience decides to move from Connecticut to York state by foot [[SweetPollyOliver disguised as a man]]. She's twenty-one but her lack of facial hair and boyish look makes everyone guess she's fourteen at oldest. This leads to trouble because she's routinely mistaken for a runaway apprentice.

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* It's a running gag in the ''LightNovel/{{Baccano}}'' light novels that, despite nearly half the cast being immortal, only Firo (already [[OlderThanTheyLook a bit young-looking]] before immortality) has to deal with the annoyances of not looking his age, such as getting carded at age ninety, being detained for claiming he was seventy on his passport, and constantly being called 'babyface.'

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* In Creator/MaryRenault's ''The Last of the Wine,'' the main character's lover has a spazz attack when he realizes that the woman the main character has been calling "Mom" for the whole book is a stepmother and about the older lover's age.

* In ''Literature/TailchasersSong'', Tailchaser is asked if he's 6 months old yet. He sheepishly mentions he's turning 9 months soon. In human terms, this is essentially equivalent to mistaking a 17 year old for a 12 year old.

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* In an episode of ''Series/{{ER}}'' an injured toddler comes in and shouts that Uncle Charlie hurt him. Someone asks if they should call Social Services only for someone else to point at another, unharmed but still grouchy, toddler, and say "That's Uncle Charlie".

* In an episode of ''Series/{{Firefly}}'', Mal invokes this trope to evade INeverSaidItWasPoison, when asked whether he has seen fugitives, "a brother and sister", by pretending to assume that the pair in question were children, when he actually knows exactly who and where they are.
* Charlie in ''Series/{{Numb3rs}}'' was once invited to a bed and breakfast in Santa Monica after publishing his first paper. Unfortunately, he was fourteen at the time and he had to break it off to a very embarrassed female professor in Berkley.
* ''Series/DoctorWho'': It's a RunningGag that the 12th Doctor (played by Creator/PeterCapaldi) constantly insists that Clara (played by Creator/JennaColeman) looks older than him, despite the fact that Capaldi is twice the age of Coleman, and as a Time Lord the Doctor is well over a ''hundred'' times older than Clara. A fan theory is that since Clara [[spoiler:jumped into the Doctor's timestream to save him from an enemy that was attacking him at every moment of his life]], the Doctor instinctively sees her as the same age as himself.

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