When you subtract the age (or apparent age) of a child from that of their parent, this results.
Typically done to justify a hot mom, but sometimes, she really was that young when she gave birth (or the other gender around). Sometimes she only appears this way because of the art style.
In Real Life, a girl can conceive as soon as she has her first menstrual cycle, generally around 11 or 12 years old... although in rare cases this can occur at an even younger age, such as five years old.note Lina Medina, the girl in question is an example of a case of extreme precocious puberty i.e. puberty at an absurdly young age, and reportedly had started getting her period while she was still an infant. She is the youngest mother ever in recorded history, though she was too young to fully remember the pregnancy and her parents raised the baby as her brother. While the girl's father was eventually cleared of rape charges, there's still the Fridge Horror question of who the parents allowed around their daughter.
Somewhat justified if set in the past when girls might get married at 12-14 and boys at 15-19. In modern times, it depends on your countryand the culture you live. Avoid posting examples of why you believe a relationship is squicky unless it is declared as such in-universe by the author or the characters themselves. This trope isn't about the morality of Teen Pregnancy or what is considered statutory rape.
Compare Playing Gertrude if the actress playing the mother is absurdly youthful.
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Actual parent-child relations with small age difference
Pregnancy at a young age is clearly implied or stated
Anime and Manga
In Haré+Guu, Hale is 10 while his mother Weda is 24. It's the reason she lives in the jungle: Her city family kicked her out.
Kodomo no Omocha: Sana's birth mother Keiko was fourteen when she gave birth. And it's implied in the manga that Sana was the product of sexual abuse, as apparently her dad was Keiko's uncle. It also would've been borderline statutory rape, since the age of consent in Japan is in between 13 and 18 depending on the prefecture, and this means Sana was conceived when Keiko was 13.
That, and two of the kids are twin girls no older than three. The third child is actually born in that same Distant Finale.
Hinagiku and Yukiji's adopted mother in Hayate the Combat Butler looks to be rather young to be the mother of 28-year old Yukiji, a little more probable for 12-years-younger Hinagiku, especially recently, but she's still nearly alarmingly young to be their mother. That she's the Katsura's adopted mother doesn't make things that much better, especially when considering that Mr. and Mrs. Katsura had apparently been trying to have children of their own for years beforehand.
Mikoto is stated to have had Wataru when she was young (and there's implication that Nagi's mother also gave birth while she was young) and actually left Wataru in the care of his maid Saki because of it. Mikoto still looks young despite having a 13-year-old son.
Rosario + Vampire gives us Kurumu's mother Ageha and Mizore's mother Tsurara, both of whom appear to be in their early thirties; the anime reveals them to have been classmates. Justified in Tsurara's case, since Yuki-Onna go sterile at a very young age, and as a succubus, Ageha probably didn't want to take things slowly either.
Marine Gabrielle de Polignac in Rose of Versailles, who had her eldest daughter Rosalie at age 14. She gave her away to her former maid Nicole, who took the baby away and raised her as a peasant. For massive irony, Polignac's carriage ran Nicole over several years later, killing her...
Karin: When Kenta was born, his mother was 16 and his father was 19.
In Gundam SEED Yzak Joule's age is given as sixteen. His mother, Ezalia's age is given as thirty-three. This means Ezalia was seventeen when she had Yzak. Given her country's aggressive pro-birth policies, this actually makes a lot of sense.
In the Lyrical Nanoha franchise, Lindy Harlaown was 17 years old when Chrono was born, and is 31 during the first series. Though she still looks like she's in her early twenties at most, and doesn't visibly age for the next decade either.
Fruits Basket: Since she got married not long after middle school, Kyoko probably had Tohru when she was 16 or 17, at most.
Played for all it's worth in Bitter Virgin, where the female lead was raped by her step father from the age of 12 and got pregnant from him twice, the first ending in miscarriage and the second born and adopted out right away.
Parodied in Don't Be A Menace To South Central While Drinking Your Juice In The Hood, where the father of Ashtray (played by Shawn Wayans) is played by Lahmard Tate, who is about a year younger than Wayans. This is a Running Gag through the entire movie, with things like Ashtray reminiscing about changing his father's diapers, and going to a party his dad is too young to attend. This was poking fun at the fact that Lawrence Fishburne, who played the father of Cuba Gooding Jr's character in Boyz n the Hood, is only about seven years older than Gooding.
Gender inverted in The Wild Hunt Trilogy. Judith's father was 14 at her conception, due to him being the only male around at a time when her 28 year old mother desperately needed to get pregnant.
In the Kate Thompson book Children of the Night, the teenaged protagonist's mother was only 14 when she had him. He realizes that his father, who he never knew, must have been an adult, as she would have told him if his father was a classmate of hers. This squicks him out, as the idea that an adult could take advantage of a young girl like that is inherently disturbing.
Gender reversed in The Shipping News, where the protagonist calculates that his grandfather must have been about 11 when he fathered a child. His aunt's reply is simply: "You don't know Newfoundlanders."
Several examples in the works of V. C. Andrews. Notably, Dawn in the Cutler series was 17 when she gave birth to Christie; Leigh Casteel had Heaven at age 13-14 (the books waver on this since the last two were finished by a Ghost Writer) and Celeste in the Gemini series is around fifteen when her daughter is born.
In Clan Of The Cave Bear, Ayla is eleven when she has her son Durc - her sister Uba isn't much off that when she gets pregnant. Justified in-universe in that the Clan have a lifespan of about thirty and go through menopause in their early twenties, and so have children early, and Ayla was held to their standards.
In Ginger Pye, Jerry and Rachel's mother married their father at the age of seventeen, at a time when such marriages were unusual but not unheard of. Their grandmother is still quite young, and they have a three-year-old uncle, affectionately referred to as "Uncle Benny" by everyone in the neighborhood.
In the Books Of Swords, it is outright stated that the Silver Queen, Yambu, became pregnant with Ariane while still barely a teenager herself. As such, when Ariane is in her early twenties, Yambu is still only in her mid-thirties or so.
The age when men are married and expected to start servicing their wives, in A Brother's Price, is sixteen. But only a generation ago, that age was only thirteen, and the Moorlands were fathered by a boy who was married off at that age. Cullen Moorland expresses relief that the age of marriage is higher now.
In Moonlight Mile, the sequel to Gone Baby Gone in the Kenzie and Gennaro Series, Patrick and Angie eventually track down Amanda McReady, a girl who went missing when she was four years old and then disappeared again when she was 16. She has a baby with her that she claims is hers because of this trope. It's not actually hers, but rather her friend Sophie's, who does actually qualify for this trope since she's the same age as Amanda.
The Maeve Binchy novel Evening Class has a young girl realizing that her older sister is actually her mother and that all of her "cool big sister" gestures were actually her going all out to be the best mother that she could possibly be despite her limits. She's the result of a teen pregnancy.
Danielle Steel frequently trots this one out, with all of her forty-something female characters frequently being said to look more like their children's older sister, thanks to them having had their children in their early to mid 20s.
Sweet Valley High: Descriptions of the characters will almost inevitably include the mention that the twins' mother Alice is often mistaken for their older sister (she's presumably only in her late 30s/early 40s given that she and the girls father met their senior year of college).
Live Action TV
In the first episode of Gilmore Girls it is explicitly stated that Lorelei had Rory out of wedlock at age 16. Another episode has Rory's friends commenting on how young she looks before figuring this out.
Full House: It's mentioned a few times that Danny eloped with his now-deceased wife Pam after their senior prom, and an episode featured a tape of a college-aged Danny showing a picture of his oldest daughter D.J, who appears to be around three or four years old in the photo. The first season also features Danny's 30th birthday (when D.J was 11 years old), so both mother and father would've been around 19 when D.J was born.
In The Borgias, Lucrezia is married at 14 and has her first child, Giovanni, at around 15. While early motherhood was common back then, this particular situation was fairly unusual even then and dangerous for the health of both mother and child.
EastEnders: Kat Slater/Moon is discovered to have given birth to Zoe at age 13 after being raped by her uncle.
Best Player featured the mother of a 16-year-old dating a 30-year-old. No mention of an age difference in the couple was made... so... How old was Chris's mom when she was born?
Tanya, the lead character's 18-year-old daughter who has a three-year-old son in Single Father. The circumstances surrounding the child's conception (who the father is, etc.) are left unstated, but it is heavily implied that estrangement from her father as a teenager contributed to the pregnancy.
In the Doctor Who episode "The Doctor Dances", we discover that Nancy is Jamie's mother rather than his sister as she claimed, and would have given birth to him between the ages of 14-16. Adding to that the fact she doesn't look older than twelve.
In Raising Hope Virginia and Burt are grandparents in their 30s, having had their son Jimmy in their mid-teens. Jimmy himself is just outside this trope having had Hope in his early 20s.
Which was normal... back then, as girls from rich families got married around that age so they'd be able to have healthy kids soon. Poorer women would marry later (around 20 or older), as possible suitors would take far more time to gather enough money for a decently-sized household.
Leisure Suit Larry: Love For Sail has Nailmi and Wydoncha Jugg, a mother-and-daughter pair of country/western singers who look almost identical. This being Leisure Suit Larry, the game hangs a lampshade on this, implying that Nailmi gave birth to Wydoncha at an improbably young age.
Fire Emblem: Genealogy of the Holy War has a few first-generation parents (or potential parents) who are very young, such as Sylvia and Dew. It's not incongruous with the medieval setting, though.
Same goes to Fire Emblem Awakening, where kids no older than 15 (like Lissa, Ricken or Donnel) are said to become parents. While in most cases it's due to their children having come from the future, a few potential pairings result in this occurring normally.
Joel from The Last of Us. He had his daughter Sarah before he could go to college.
Nagisa gave birth to Ushio at age 21. In the anime she falls victim to Death by Childbirth, but she survives in the visual novel's True End. She also most likely possesses her parent's genes for mysterious eternal youth.
Seems to be very common in Clannad or just Key's works in general. Tomoya's mother gave birth to him shortly after marrying her husband. His parents married when his father was still in school.
Sakura's mother in Kare wa kanojo. She was seduced and impregnated by her then-teacher.
In Umineko: When They Cry, Beatrice Ushiromiya, first introduced in EP3 as the Beatrice from 1967 is revealed to have been this. She was in fact Kinzo's illegitimate daughter with his secret lover Beatrice Castiglioni, but her mother's Death by Childbirth drove Kinzo into such despair that he eventually deluded himself into believing that she was her mother's reincarnation, and it's all but outright stated that he raped her, making her pregnant with a Child by Rape at a young age.
Foxxy Love is implied to have something like this trope with her kids.
At one point a member of Foxxy's family shows up and looks to be about 14 or 15. He introduces himself as being Foxxy's grandson. So unless Foxxy is just way older than she looks, both she and her own kids must have their kids at very young ages.
Doughy Latchkey's parents Karl and Kim on Moral Orel both look and act like teenagers. They were shown to be in high school with Stephanie 12 years ago, so they probably had Doughy not too long after that.
Parents remarried, adoption, or gained custody through other means
Anime and Manga
In Elfen Lied, Kohta and Yuka (both 18-19) are given custody of Mayu (~13) by her mother as she doesn't want her any more.
The title character of Lyrical Nanoha officially adopted the then 6-year old Vivio when she was just 19. One fan comic had fun with this small age difference by having Nanoha introduce Vivio to her parents with no prior information, causing her father Shiro to have a breakdown when he thought that she got Vivio the usual way at the tender age of 13.
There's also Fate, who's the official guardian of Caro even though they only have a 9 year difference between themnote Technically, it's only a two year difference, since she was a clone created only a few years before the events of the first season. Erio would also count, but he's officially under the guardianship of the forty-something Lindy since he was rescued back when Fate was still too young to officially be his guardian. Fate goes on to become Vivio's other mother, as well as Lutecia's legal guardian for the time when her mother Megane is still in her coma.
Averted with Subaru Nakajima who, while likely old enough to become Tohma's guardian in Force, despite being only six years older than he is, asks her father to take him in instead (presumably, she'd much rather be his sister).
Eureka (14-16) of Eureka Seven has three adopted children, all orphans. She's the one who orphaned them.
In the epilogue, all three children are adopted by Renton as well, who is also 16, as Maurice, Maeter, and Linck all are shown to have the last name Thurston. It is also implied that Renton and Eureka are married, at least legally.
Possibly averted with Ao, though her actual age when giving birth to him is not yet known.
At age 15, Fraw Bow from Mobile Suit Gundam starts taking care of the orphans Kikka (4), Retsu (5) and Katz (8). Seven years later, we see them again in Mobile Suit Zeta Gundam: 22-year-old Fraw has married her Victorious Childhood Friend Hayato and they have adopted the three kids, who are now 11 (Kikka), 12 (Retsu) and 15 (Katz, who even joins the cast as a regular).
In Sailor Moon, the Outer Senshi (all 16-17) adopt Hotaru after she has magically regressed to an infant. She then magically re-ages to around 13.
Yuuri (16), from Kyo Kara Maoh!, adopts the ten year old girl, Greta, who tried to kill him in her first appearance.
Satoshi, from D.N.Angel, was adopted as a teenager by a man in his twenties.
Beelzebub: Oga is made Baby Beel's foster father through a Deal with the Devil at age 15, while the foster mother Hilda is 16. However, virtually everyone else assumes that they are Type 1 teen parents.
Bleach: Thanks to Abusive Parents, Sora Inoue kidnapped his sister Orihime Inoue when she was three years old and running away from home. His act saved Orihime's life but left him Promoted To Parent at the age of eighteen.
In the Age of Apocalypse, Rogue married Magneto and thereby became the adoptive mother of the sole survivor of his children, Quicksilver. He is an unspecified number of years older than her. (It could still happen in the main timeline).
In the current adjectiveless X-Men series Jubilee finds and adopts an abandoned baby she names Shogo. This despite only being 17, and thanks to being turned into vampire she'll be the same age even as her kid grows up.
Then in Bill and Ted's Bogus Journey, we find out that she divorced Bill's father... and married Ted's.
Paige of Women Of The Otherworld adopted Savannah when Paige was 23 and Savannah was 13. Then Paige marries Lucas Cortez, also in his mid-twenties, and Savannah has two parent figures less than a decade older than her.
Twenty-five-year-old Kate Daniels becomes the legal guardian of twelve-year-old Julie. At first Kate refers to herself as a substitute mom, then as a crazy aunt, but she always refers to Julie as her kid.
In the Flowers in the Attic series by VC Andrews, it's a significant plot point that Malcolm Foxworth fathered a child (Corrine) with his stepmother Alicia, who was sixteen when she married his father - a decade or more younger than Malcolm. He even states in front of his father that he cannot acknowledge a girl so much younger as his new "mother".
In Randall Garrett's Lord Darcy stories, every story that Mary, Dowager Duchess of Cumberland is in also contains an explanation that she's a year younger than her stepson, the current Duke of Cumberland. She was his father's second wife, and it was a May-December Romance — she was in her 20's, he in his fifties when they married.
In Adrian Mole: The Wilderness Years, Adrian's mother falls for and marries her lodger, who is around the same age as Adrian. The guy eventually leaves her and runs off with Adrian's own girlfriend.
In The Hallowed Hunt, Ijada's father died, and her mother remarried. Then her mother died and her stepfather remarried. When Ijada explains this, Learned Hallana asks:
Hallana: And she's ah, how many years older than you?
Live Action TV
In Just Shoot Me!, Maya's father marries a woman who's exactly the same age as Maya. In fact, they used to go to school together.
After serving as the fake 18th head of the Shiba household, Samurai Sentai Shinkenger's Takeru is adopted into the family to become the actual 19th head in the finale. It's stated that the 17th head, Kaoru's father, died 17 years before, making the new adoptive mother 16-17 years old and younger than her son who, from his age in flashbacks, appears to be 6-8 years older than her.
Ryouga in Bakuryuu Sentai Abaranger is an Absurdly Youthful Father; he is 21 with parental responsibility for his orphaned 6-year-old niece.
Kendall Casablancas of Veronica Mars has stepsons 7 and 9 years younger than she.
In Modern Family Claire and Mitchell's stepmother Gloria is roughly the same age as them - it's stated at one point that Gloria is in fact a few months younger than Claire, and less than two years older than Mitchell. (In fact, Sofia Vergara, who plays Gloria, is two years younger than Julie Bowen, who plays Claire, and just over three years older than Jesse Tyler Ferguson, who plays Mitchell.)
In Defiance, Nolan doesn't look much older than his adopted Irathient daughter, Irisa . Their respective actors are about 10 years apart in age.
In A Little Night Music, Anne is eighteen and her stepson Henrik is nineteen and madly in love with her. They run away together.
In Ace Attorney Trucy's dad Phoenix "Nick" Wright is 33, while she is 15. Protagonist Apollo does the math and is mind boggled by the implications of this fairly small age gap. However, it later, thankfully, turns out that Trucy was adopted by Phoenix. (Of course, long-time players of the series could guess that already long before that point) In a straighter example, however, her older brother Apollo is only 18 years younger than their biological mother.
In Princess Maker 2, you can be a very young man when you adopt your daughter (in fact, you can adopt her at 11, and she starts at 10...).
In Tales of Symphonia, 12 year old Genis's sister, sole caretaker and mother figure is Raine, age 23. She's been raising him since infancy, making her roughly 11 or 12 when she had to start taking care of him because their mother abandoned them. It's implied in a Z-Skit that she's been a school teacher in Iselia for around six years, but it isn't clear what she did to support them before that.
In Homestuck, Dave's much older brother is revealed to be his genetic father, through cloning shenanigans. The author indicated that Bro is 28 years old, so he had to have been about 15 when he adopted Dave. The same likely goes for Rose's mom, who is also quite youthful.
Subverted in that the children she cares for are her cousins and little sister but Bunny is in early to mid twenties, though, she hasn't given birth to any children to speak of but she is considerably a bit young for motherhood. It is stated here that she didn't even finish college when Madgie came to live with her and is studying online so she can do so as to better provide for her youngest cousins.
In Daria, Brittany 's stepmother Ashley-Amber is about 10 years older than Brittany herself.
King of the Hill has Hank's stepmother Didi, who was his classmate in kindergarten.
Star Wars: The Clone Wars included an episode involving a clone deserter with young children. He's no older than 13 at this point while his children are about 5-6, but he's been fast-grown so physically he's in his mid-twenties, and the children are his step-children.
This was the subject of the song his own grandpa, a hit for Guy Lombardo in 1948.
Too many to even start listing them. Let's just say that the above Bill and Ted example is not even remotely far-fetched.
Parent and child ages (or looks) are somehow modified
In Dragon Ball GT, Goku is de-aged to childhood as the result of the Dragon Balls, making him approximately the same age as his granddaughter, 10-year-old Pan.
Even before that, Goku was looking young to be the father of his professor son Gohan (also keeping in mind that Gohan's own kid brother, Goten, is a teenager) but this is because Saiyans remain in their prime longer than humans. Neither Bulma nor Chi Chi are thrilled, and you can guess how the latter reacts to her husband's further de-aging.
Also, Goku's age was stilted by about 8 years (which is about the difference between Goku and Vegeta's dates of birth to begin with) due to times he spent dead.
Their "official" ages in A's, most likely determined by physical appearance, are 8 for Vita, 19 for Signum and 22 for Shamal. Zafira seems to pose as the family dog.
RahXephon has Quon, Ayato's "mom", who has been kept in stasis. Making her the same age as he is, and about alf the age of his twin brother Itsuki (Ayato too was kept in a kind of stasis)
Moka's mother Akasha in Rosario + Vampire is well over 200, but looked like she was in her early twenties (she looked like just like her daughter's good side, in fact). Justified, since her species are said to be immortal. Her daughter really is 17, though.
Tenchi Muyo! has several of these, perhaps most notably Washu being Ryoko's mother, despite the fact that Washu actually looks younger than Ryoko. In actuality, while Ryoko is merely a child at 7,000 or so, Washu is, depending on who you ask, either 20,000 or older than the universe. She cheats via magical scientific age modification.
In Sailor Moon, there's Chibiusa (who looks no older than 8, or 10 after she starts becoming Sailor Chibimoon) to Usagi (who is 14). Chibiusa is actually Usagi and Mamoru's Kid from the Future, born into a future a thousand years from the series' present day where the latter two have ascended to rule the world from Crystal Tokyo as Neo-Queen Serenity and King Endymion. Also, due to the extended lifespan of the future people, Chibiusa is actually 901.
Cable from X-Men (picture above) is about twice the biological age of both his parents, Scott Summers and Madelyne Pryor; he was born in the present but was spirited away and raised in a distant future. Additionally, his mother was a clone of Jean Grey, and chronologically only a couple of years old when he was born. (It's complicated)... Just remember that he's a time traveler.
Same goes for X-Man (Alternate Cable. He's made from Scott and Jean's DNA by an Evilutionary Biologist, grown to adulthood, looks 20 while parents are getting toward 30) and Rachel Summers (Scott and Jean's daughter presumably through normal means, returned from a Bad Future that may or may not still occur.)
In the Yoko Tsuno book The Three Suns of Vinea, Khany is reunited with her mother, who was put in suspended animation at the same age Khany is now. As a result, mother and daughter now have the same biological age, prompting the former to try to make things less awkward by insisting that Khany consider her her sister rather than her mother.
Adam Destine of ClanDestine hasn't aged since the genie Elalyth made him invulnerable when was about twenty... eight hundred years ago. Since then, he and Elalyth have had a great many children, all of whom age normally until adulthood, then slow way down. Most of his children actually look older than him, except for the twins (twelve years old) and Samantha and maybe Dominic (who look about the same age as he does).
From the Hulk comic, the organization known as The Pantheon is lead by centuries-old, but adolescent looking Agamemnon. His immortality kicked in while young. His many sons, grandsons and grand-grandsons looks older than him.
However, he usually takes the appearance of a towering old man with a long, white beard when he appears at the Pantheon.
A popular strip in the British comic Bunty involved a scientist who invents a miraculous anti-ageing cream that turns her into a 15-year-old, forcing her to go to school with her daughter so the welfare authorities will not ask questions.
The 2011 sci-fi thriller In Time features this. The premise of the film is that humanity has discovered the technology to freeze everyone's age at 25 and now live on internal "time-clocks" which expire after a set period, and people who don't work or don't buy units of time die. The extremely wealthy can purchase enough units of time to indefinitely remain the same age for years (or even decades) - in the film's trailer, a man introduces his wife, daughter and mother-in-law, all of whom are the exact same age.
The Neon Genesis Evangelion web comic fanfic Aki-chan's Life (a slice of life/ illustrated epilogue to another, very well written, fanfic called The Second Try) has a somewhat... complicated example. Aki the daughter of Asuka and Shinji, conceived after the events of the third impact was born when her parents were about 16 or so. Pretty young to begin with. Four years pass, then everyone was swept back in time and her parents returned to the age they were in the anime (14) while she remained unchanged (she's a very precocious 4). They still remain loving, mature parents, but the awkwardness of the whole situation is... well you get the idea.
Another Eva fic, Nobody Dies, has two examples: the Reego and the Keiworu. The Reego are virtual constructs made by Iruel for Rei's Lotus-Eater Machine, as theoretical offspring of her and Evangelion Unit 05 (yeah, Iruel was squicked too). Unit 05 "saved" them from deletion when Iruel was defeated and now they exist as AI's in the real world (technically, they've been revealed as Iruelim-class Angelic lifeforms), and consider the 16-year-old Rei and the... much younger Unit 05 to be their parents. The Keiworu are AI copies of Kei Ayanami's mind randomized with elements of Kaworu's mind (both of them being 16), and also consider the two to be their parents.
The Return, Sunshine comes across as one of these to Muggles due to the complicated nature of Succubae relationships (in purely chronological terms she could actually be younger than 2 of her kids).
In Not Normal Harry's mother, not trusting Dumbledore, set up a complicated spell intended to swap her, James and Harry with transfigured pig corpses as soon as a potentially-lethal spell hit them, leaving them in blood-sealed medical stasis afterwards. For unknown reasons this only worked on the adults, leaving a fourteen-year-old Harry to encounter his still-in-stasis twenty-year-old parents.
In the Doctor WhoEighth Doctor Adventures novels, the Eighth Doctor at one point mentions being a grandfather — he appears to be in his mid-thirties at the time. His companion Fitz is a bit confused. He later adopts a young girl named Miranda, who ages rather normally, so he looks about forty (and claims to be thirty-six) when she's sixteen, which other characters see as slightly unusual. But after she leaves to have her own life and they're later reunited, several decades have passed since the last time they met, so she actually looks older than he does.
In the Codex Alera series, watercrafters often, in addition to being able to sense emotions and act as medics, seem to age slower, so that some that die of old age in their 80s or 90s look no older than someone in their late 30s or 40s. Most of the watercrafters we see aren't parents, but there are a couple. Lord and Lady Antillus, Crassus' and Maximus's parents, are prominent examples. Isana is revealed as Tavi's mother and starts the series approaching 40 and by the end is still described as looking like a girl of 20 aside from her grey hair. Gaius ends up being an Absurdly Youthful grandfather. He's well over 80 by the time the series starts, but outwardly appears to be a man in his 40s.
A really bizarre case in Twilight with Bella Swan-Cullen and her daughter Renesmee. She gave birth to her just before her nineteenth birthday, but since she got turned into a vampire at the same time AND her daughter ages faster than a normal human, eventually they'll both look the same age.
At one point in To Sail Beyond the Sunset, Maureen mentions her 150th birthday. Her son, Lazarus, is well over 2000 at that point. She was collected from 20th century Earth and brought to another planet, skipping a couple of millennia of time that Lazarus simply lived through.
Live Action TV
The main character of New Amsterdam is 400 years old but looks 35 (the age at which he became immortal via magical means); he sometimes seeks advice from one of his still-living sons, who is a naturally-aging 65-year-old.
Takeru Sato, the lead actor of Kamen Rider Den-O, left the franchise after the TV series; so for future movies and spin-offs, they de-aged Ryotaro into an 11 or 12-year-old boy, making him younger than his grandson Kotaro who is around 18.
Due to the characters being taken from different points in their timelines, 19-year-old Yuto Sakurai is around the same age as his daughter, Hana. Hana's mother, Airi, is in her late 20s and thus only a decade or so older than Hana.
Thanks to time travel in Kamen Rider Kiva, father and son Otoya and Wataru meet when they are 23 and 18 years old respectively. In the finale, Wataru meets his own teenage son from the future.
Kiva also features Wataru and Taiga's mother Maya who, being a Fangire, doesn't age at the same rate as a human and looks around 20 years old; appearing younger than Taiga, who is in his mid-to-late 20s.
In Rentaghost, ghosts manifest as they age they were when they died. So Hubert Davenport's mother, who died in her twenties, looks much younger than her son, who died when he was much older (his late fifties or early sixties).
In Angel, the title character's son Connor is kidnapped as an infant and trapped in Another Dimension where time passes much more rapidly, so when he reappears a few months later- from the perspective of the other characters- he is already in his teens. Angel also only looks young; as an immortal vampire, he is Really Three Hundred Years Old.
Doctor Who takes this to insane levels, where, due to a mixture of time travel, Regeneration and slower aging, Melody Pond is physically in her 40s for much of the series (though chronologically at least a decade older by her River Song incarnation]]), while her parents are physically in their 20s (though mentally, her father is technically almost 2000).
When we first meet the Doctor, he is an old man played by William Hartnell, and realistically has a teenaged granddaughter played by Carole Ann Ford. For the show's 20th anniversary special Susan returns, but the Doctor is now Peter Davison, so his granddaughter looks significantly older than he is (Ford was eleven years older than Davison).
Xena example: Xena was presumably in her 30s when she had her daughter Eve. Shortly after Eve's birth, she and Gabrielle were frozen in ice for two decades. When she emerges unaged, she doesn't look that much older than the 20-year-old Eve.
Bakuryuu Sentai Abaranger: Asuka and Mahoro are both around their early 20s, but due to their infant daughter being used as a host for the soul of the Big Bad, she first appears as a child of around seven and then a young woman in her late teens, while her parents remain the same age.
In Once Upon a Time we have three generations of women, Emma Swan (Jennifer Morrison), her mother Snow White/Mary Margaret (Ginnifer Goodwin), and Snow's stepmother Regina (Lana Parrilla), who are all played by actresses within five years of each other. However, Mary Margaret's and Regina's aging were frozen by the curse (It's complicated), and Regina is certainly implied to be closer in age to Snow White than her actual mother was.
Lampshaded at the beginning of series two by Henry calling Charming "Grandpa" for the first time - Henry is ten years old while Charming is in his early thirties at the most.
Also Rumplestiltskin's father Peter Pan, who looks young enough to be Rumple's grandson. Pan gained eternal youth in Neverland, while Rumple aged normally until he became the Dark One
In Red Dwarf, Kochanski is roughly the same age as her son. She conceives him after meeting him as an adult, and the baby is taken back in time by his adult self. Her son is Lister, who is also his own father.
In Fringe, both Olivia Dunham and Peter Bishop wind up as absurdly youthful parents of their now-grown daughter after they are trapped in amber for 21 years.
In the Gilbert and Sullivan operetta Iolanthe, the hero Strephon is half-fairy. Fairies are unaging and Strephon has a hard time explaining to his beloved that these nubile women he is seen embracing are, in fact, his mother and his aunts, all of whom look younger than him.
I wouldn't say a word that could be reckoned as injurious But to find a mother younger than her son is very curious
Golden Sun's player characters, along with Alex and Kraden, were all exposed to age-slowing amounts of Alchemy at the end of The Lost Age. So thirty years later, in Dark Dawn, the former player characters all appear to be in their mid-to-late twenties, with teenage or young adult children. Alex was exposed to more of Alchemy's power than anybody else and is basically immortal: The only reason he looks older than his child at all is because the kid in question doesn't look nineteen.
Karis complains about the ramifications of this trope... which makes sense when you remember that her father, Ivan, was the youngest of the original protagonists, and probably doesn't look much older than Karis herself now (and probably far younger than her mother).
Nina Williams from the Tekken series is 22 years old, and thanks to a 19-year-long cryogenic sleep, is only 2 years older than her son, 20-year-old Steve Fox.
In Touhou, Sanae Kochiya is a distant descendant of the goddess Suwako Moriya. Suwako actually looks much younger than Sanae, though since she's a goddess who's been around for a long time it's likely that she didn't always appear to be so young.
Dragon Quest V: While the hero and his wife have children at around 16-18 respectively, they are turned into stone the day after the birth, and aren't freed until eight years later by the kids. Which is why they're about ten years apart in appearance.
Tsugumi in Ever17 doesn't look much older than her sixteen-year-old children, as she stopped aging at seventeen. You's mother is a more conventional really-young-looking parent... because her "daughter" is really a clone of herself that she had made when she was diagnosed with a terminal illness in her teens, and You'haru stopped aging too, at the age of twenty.
In Higurashi: When They Cry, it's revealed in the TIPS/Rei OVA that Hanyuu, who looks about anywhere from 8-12, in fact had a daughter way back when. She was actually an adult when she had her child in life but appears as a young girl in order to get Rika to better relate with her.
You might not suspect it, but Drowtales' Queen Diva is a great-great-great (times x) grandma and well over 1000 years old by the time the story starts, which isn't unusual since fae (dark elves, drow, drowussu, etc.) stop aging at the human equivalent of 30 years old, so parents often end up looking the same age as their children and vice-versa. Additionally, Diva's Fusion Dance, Ragini/Liriel, makes her look about 12 once she fully manifests, which leads to a hilariously awkward moment where Diva meets two of her grandchildren and looks the same age as her granddaughter, to the point that Chrys'tel's clothes (from 22 chapters earlier) fit her perfectly.
Maria Delacroix in Eerie Cuties. Nina and Layla's mom does not look like could have had 13 children. Justified in that she's a vampire. (Vampires can reproduce in this verse the same as humans.) Then we meet Adora Love, though Chloe's mom said herself that an adult succubus have free choice as to her body's age.
Magick Chicks adds Anastasia Hellrune. Now we know from whom Melissa got the looks — she could give even Adora a run for her jewelry. Of course, she's also implied to be a witch...
In Homestuck, in every session of Sburb, it is predestined that the players will almostnote Exception: Caliborn and arguably Calliope all really be paradox clonescreated by one of the players during that session. While this process isn't explicitly shown in the Trolls' session (though the end result is), in the kids' session, we see that John first created Nanna Egbert, Grandpa Harley, Bro Strider, and Mom Lalonde and then created the children themselves by combining this quartet pairwise, thereby making them essentially just a few minutes younger than their biological parents, whom in most cases were also their acting parents due to having been sent to different points in time. John, however, is quite a bit older than his "father", who is actually his half-brother. On top of that, if you consider creating the paradox clones to be a form of parenthood, this means that John is, at age 13, either a father of eight or a father of four and a grandfather of four, or both, depending on your perspective as to whether the second generation should be considered children as well or grandchildren. In short: Stable Time Loops and genetics should never mix.
In The Order of the Stick, when Roy meets his mother in the afterlife, he doesn't recognize her because she's no older than he is. His father, meanwhile, looks like an old man. Sara explains that his father always was an old man at heart, while she thinks of herself as a young woman still.
In Mary Shelley's Frankenhole, Frankenstein and Elizabeth's two sons, Heinrich and Gustav, are doddering, senile old men while Victor and Elizabeth, due to an immortality potion, are still physically young adults.
Goliath and Demona both look too young to be Angela's parents in Gargoyles due to a combination of time travel, magic, bizarre alien biology, AND immortality.
No actual small age difference between the characters
Nana Sawada, mother of protagonist Tsunayoshi from Katekyo Hitman Reborn!, is in her mid-late thirties but looks barely older than her teenage son.
Miyuki Asaka of Game X Rush falls squarely into this trope; even the mangaka mentions that "I feel like her face and personality are stuck as a little girl forever." Also a borderline Type 1 case since simple math shows she'd have been 18 when she had her son.
In a similar vein to Sanae, Miyuki Takara's mother Yukari in Lucky Star looks like she could pass herself off as an older sister. Then again, it is a Improbably Female Cast.
And if Yukari, then certainly Miki, the mother of Inori, Matsuri, Kagami, and Tsukasa. She's claimed to be 47, and although it was a lie (she thought it was cute and expected), a 47-year-old woman could easily have four college-age daughters... but she still looks like she could be one of the sisters herself.
Ah! My Goddess: Takano Morisato could pass for a sister of Keiichi and Megumi, instead of their mother.
In Star Driver, up until the reveal, the best evidence against the theory that Reiji Miyabe/Head was Takuto's father was that he didn't look like he was out of highschool himself, much less old enough to father a fifteen-year-old son. Turns out that he ages really well. Or not at all, apparently.
In Medaka Box, Zenkichi's mother even passes as an elementary school student, despite being 42 years old.
Bulma's mother from Dragon Ball. While Bulma's character model is appropriately updated for her age, as she goes from 16 to 43, her mother's never changes. The result is that in some of her last appearances she actually looks younger than her own daughter.
Android 18 as well, though she does look a little older by the time GT rolls around. Being a cyborg, she presumably doesn't age at the same rate as a normal human.
Akira's parents in Family Complex could pass off as 17 despite being around 40 years old.
Lampshaded in the Princess Princess crossover manga when Toru and Yuujiro try to guess who is who in the Sakamoto family. They tend to get it wrong.
In Code:Breaker, Sakura's mother was mistaken as her elementary school sister. It also doesn't help that she likes to cosplay as one.
A Spear Counterpart example from JoJo's Bizarre Adventure: Jotaro Kujo is 40 years old and a father as of Stone Ocean, but you'd never know it from the way he's drawn. At most, he looks maybe a couple of years older than his teenage daughter.
Before that, there was Lisa Lisa, a fifty-year-old woman who looked no older than her son, Joseph Joestar. Joseph's brain takes over two pages to process the idea that she could possibly be over twenty.
Suite Pretty Cure ♪ has Kanade's mom Misora. When the fans first saw her on the previews for episode 4, they thought she was a candidate for a possible Sixth Ranger.
Tamako Market: Tamako's mother, Hinako◊, looked almost exactly like her daughter, one can assume she was this. Mochizou's mother, Michiko, definitely counts, she looks young enough to be mistaken for her son's older sister◊.
In Rising Powers Harry's adoptive mother was an eighty-six-year-old dryad who looked sixteen.
In Alfred Hitchcock's North by Northwest, Cary Grant was 55 years-old. Jessie Royce Landis, who played his mother, was 63 years-old, meaning she would have to have given birth when she was 8 years old.
In Earthquake (1974), Lorne Greene and Ava Gardner — only seven years apart in age — played father and daughter.
In Nowhere Boy (2009), John's mother Julia looks way to young to be a mom
In the film version of Harold Robbins’ Where Love Has Gone (1964), Bette Davis plays Susan Hayward’s mother, despite being barely ten years older.
It's been mentioned a few times in The Hollows that witches age slowly once they reach adulthood, which presumably leads to a lot of this. Case in point: Rachel's mother is past retirement age for a human, but can pass for Rachel's sister with the right clothes.
In Sweet Valley High, Jessica and Elizabeth's mother is in her late 30s-early 40s (thanks to frequent Retcon between different ghost writers, it changes) but it is often stated that she looks like she is in her 20s, and is usually mistaken for the twins' older sister.
In The War Of The Dreaming series, Wendy and her mother, Queen Titania are said to look about the same age, or even, that her mother is younger looking. Justified, since she is an immortal who never ages
Merlin's mother Hunith looked normal enough in the first season, when Merlin himself appeared extremely young and was described as a "young boy" in the Opening Narration. Five years pass in the show's time-line, and when Hunith reappears, looking exactly the same as she did half a decade ago despite her son's sudden growth spurt (and now refered to as "a young man"), she is suddenly this trope. She almost looks younger in her series 4 appearance than in her series 1 appearance, while Merlin has definitely gone from boy to man. Judge for yourself: Hunith◊ and Merlin◊ in Series 1, Hunith◊ and Merlin◊ in Series 4.
Yuki's mother in Grandia III, who is 34 while he is 16, but looks about 20. For most of the game, they have more of a sibling relationship than a typical parent/child one, made clearest by the fact that Yuki calls her "Miranda" rather than "Mom."
In Dragon's Lair 2, Princess Daphne has 13 kids, the oldest of whom looks about 13, and she still looks exactly the same as she did in the first game.
In FireEmblem: Radiant Dawn, Almedha appears to be a beorc woman in her early or mid thirties, a bit too young to be the mother of Pelleas (who appears to be in his early twenties). She is neither.
Fridge Logic means the same applies to Apostle Misaha, who, due to having the exact same brand as her oldest granddaughter, would have still appeared to be in her early thirties when said granddaughter was born.
In Metal Gear Solid 4: Guns of the Patriots, Big Mama actually looks very well for being almost 80 (and still doing some pretty crazy motorcycle stunts during a highly destructive car chase). Her son Solid Snake also suffers from severe Cloning Blues and has rapidly aged in the last years to look actually older than her, even though she was over 30 when he was born.
In CLANNAD, Sanae Furukawa looks like she's only slightly older, at most, than her daughter Nagisa. Fitting, seeing as she's a hot mom. She looks young enough to pass for being the granddaughter of her granddaughter's paternal great-grandmother, who is herself quite young for being a great grandmother.
She also fits in the "pregnancy at a young age folder" since its stated that she was pregnant at a young age. Combine it with this folder and it comes as no surprise that she is also a hot grandma, who perfectly could to be mistaken by the mother of her granddaughter, at least.
In the ''Good Times" cartoon "Curly The Littlest Puppy" Hayley's mother doesn't look too much older than her oldest brother Michael who's stated to be 16 and all together the parents have 5 kids.
Parents that were young but still considered adults when the child was born
Anime and Manga
In Prince of Tennis, Taka-san's friend Akutsu Jin from Yamabuki is fourteen, and his mother Yuuki is about 33. She insists on being called 'Yuuki-chan', even by Taka, leading to the other Seigaku regulars believing he has an older girlfriend. When they find out the truth, they freak and remark that she's a 'young mother'...
At the beginning of Dragon Ball Z, which takes place five years following the end of Dragon Ball, Goku and Chichi are both 23, while Gohan is 4.
Japanese source material stated that Delia Ketchum of Pokémon fame was 28 when Ash embarked on his journey. And since kids start their journey at the age of 10, this makes Delia 18 when she had Ash.
Sakura from Hanamaru Kindergarten had her daughter Anzu at age 18, so by the time Anzu starts going to the titular school, her mother is still young and pretty. Then again, pretty much every mother in this series is still quite young and beautiful.
Likely Maka Albarn's mother in Soul Eater. Both her parents were students in the same class at Shibusen and it's canon Spirit was 18 when Maka was born. Although details on the woman herself are sketchy, implications about the staff as a whole makes this a possibility.
In Weiss Kreuz, Omi's admirer Ouka Sakaki is 15. Her mom Shizuka is 34. Do the math.
Bleach: A flashback arc set 20 years before Chapter 1, and 5 years before they become parents, implies Masaki is around 15-16 years old and Ryuuken and Kanae are around 16-17 years old. That means Masaki was around 20-21 when Ichigo was born, and Ryuuken and Kanae were around 21-22 when Uryuu was born. The Japanese age of majority is 20. In the main storyline, Ryuuken therefore has a 17 year old son and is the medical director of the major urban hospital while only being around 38-40 years old.
Gears of War had Dominic's wife, Maria. Not much as youthful, but she got pregnant at the age of 16. She did reach her thrities though.
Harry Potter's parents Lily Evans and her husband James were only 20 when they had Harry. While wizards are considered adults when they turn 17, it's still a fairly young age to get married and start a family. Justified, as Molly Weasley reveals that during the First Wizarding War, a huge number of couples married and settled down as soon as they could, for fear that they would die in the war. Funnily enough, Molly herself was 21 when she had her eldest, Bill...
The pattern of hasty courtships and marriages was repeated somewhat during the Second Wizarding War, so it's not hard to imagine that there were a few instances of this trope in-universe at that point as well.
Live Action TV
Power Rangers Samurai. Spike, the son and Expy of Skull, looks a bit younger than Skull did when we first met him. This sure seems to make Skull one of the more-responsible teen dads out there, though there's a lot about the timeline we can't be sure of.note Mainly this - If we assume time passes the same as in reality unless stated otherwise, then do we say a year passed during SPD (taking place in the future), RPM (taking place in an Alternate Continuity), or the year that was all butchered MMPR reruns? That leaves us three years of wiggle room; if we assume he was 18 when he graduated high school at the beginning of Turbo, he is either 30 or 33 at the beginning of Samurai. Spike looks about 15. Therefore, the timeline allows for Spike have been born when Skull would have been out of high school - but only just! It also allows for him to have existed offscreen during most of Bulk and Skull's MMPR antics.
In Mahou Sentai Magiranger, Miyuki, the mother of the five Ozu siblings looks to be in her early to mid-40s. According to Word of God, her eldest son Makito is 24-25 during the run of the show, so it appears that she was no older than around 20 when he was born.
Janey in My Family gives birth to Kenzo when she is 18-19, shortly after the character was supposed to have gone to university (she drops out after having a child).
Live Action TV
In Only Fools And Horses, Del wins a family holiday for the Trotters by entering a children's art contest with a picture painted by Rodney when he was 14. In order for them to be eligible to claim the prize, Rodney (who's in his early 20s) has to pose as a 14-year-old boy, with Del (who was 16-17 when Rodney was born) pretending to be his father. Del at least has the sense to claim Cassandra, about the same age as Rodney, as a stepmother.
Tracy Jordan's adult son on 30Rock is far too old. In an aversion, Tracy sees through the deception immediately (while his friends assume the Cloudcuckoolander was actually taken in).
In Avatar: The Last Airbender season 3, Sokka and Katara fake being Aang's parents at a Fire Nation school. The two of them are barely older than he is and wear unconvincing disguises (Sokka wore a fake beard, Katara wore a pillow stuffed under her shirt to make her look pregnant.) to pass themselves off. To really blow some heads, just remember that in terms of pure chronological age, he could be their great-great grandfather.
Cardcaptor Sakura: It is never stated how old Syaoran's mother Yelan is, only that she looks very young and beautiful enough to stand out in a universepopulated by The Beautiful Elite. She is, however, thought to be somewhere in her mid-to-late 30's, and possibly married as a teenager. This is never confirmed, because she is only seen in the first OVA.
In Dragon Ball, it's never stated how old Bulma's mother◊ is. Assuming that she is Tights' mother, too, then that would put her at least in her early 70s as of the Buu Saga.
As mentioned above, in the dub of Digimon Tamers, Ruki/Rika's age was altered, but the age of her mother was left alone. Ruki is implied to have been the result of a teen pregnancy in the original. The dub's numbers indicate that Rumiko gave birth at thirteen. Oops.
Haiyore! Nyarko-san gives us Yoriko Yasaka, who appears at worst to be in her late 20s, an impression aided by her being a hardcore Gamer Girl who loves outdated consoles. The real disconnect comes when you put her alongside◊ her 17-year-old son Mahiro, which makes Yoriko look much more like an overly affectionateCool Big Sis than a mother. This gets emphasized even further in an episode where Yoriko flashes back to the day her husband proposed; the only visible change after roughly two decades is her hairstyle.
Films - Live Action
In The Haunted Mansion, Marsha Thomason plays Sara, a mother whose daughter and son are aged 13 and 10, and who is implied to be around the same age as her husband, who is played by Eddie Murphy and obviously meant to be in his late thirties/early forties. In reality, she is less than fourteen years older than the actors who portrayed her children, and was clearly only in her mid-twenties when principle photography took place.
In One Life to Live, Greg is explicitly stated (in courtroom testimony, no less) to have ten years' experience as a fully licensed practicing neurosurgeon, putting him in his early 40s at the youngest. His mother is played by an actress in her late 40s, and to make things interesting he has a 15-year-old sister. All the characters were introduced during 2009 so SORAS isn't involved.
Supernatural. John Winchester may be ruggedly handsome with a beard, but this hardly hides the fact that he looks MAYBE ten years Dean's senior. The same is true of his wife Mary when she appears in an alternate reality where she is still alive in the present day, played by the same actress who plays her in flashbacks to the brothers' childhood.
Dead or Alive: Ayame, the mother of Hayate, Kasumi, and Ayane. She's had three kids, Hayate being in his early twenties and Kasumi and Ayane being in their late teens, and in her every appearance so far, she doesn't appear to be much older than Kasumi.
Homestuck. Bro Strider. Most fans think of Bro as being in his early/middle 20s, until you sit down and do the math. He was at least an adult - 18 - when he adopted baby!Dave. Dave is thirteen now, making bro at least 31. The same might apply to Mama Lalonde and Dad Egbert, but Mom and Dad seem to be thought of as "older" than Bro, so I don't know. The whole lot of them don't seem to change in appearance between adopting their children and thirteen years later.
The Egbert Family. Nana was born in 1910. John was "born" in 1996. Dad appears to be a regular middle aged man, but if Nana had Dad around age 20 (as was normal for a woman of her time period) Dad would have to be in his sixties when John is "born." If Dad is about, say, 40 when John is 13, Nana would have had to have given birth to him in HER fifties-sixties. It's unclear how old Dad is SUPPOSED to be, but so far it doesn't seem to add up when considering Nana's and John's ages.
Kill Killer features a story with a "Dirty Callahan"-like killer of pedophiles who, after a lengthy period in prison for beating the supposed killer of his five year old child, reunites with his partner, the mother of the child... a 19 years old woman. Someone obviously couldn't make a subtraction...
Anime and Manga
In Sword Art Online, Kirito and Asuna adopt the AI Yui as their daughter. At the time, Kirito and Asuna are 16 and 17, respectively. Yui, by virtue of being an AI appears to be 8 despite in fact being 2.
Twilight adopts the magically generated Nyx. Biologically, they're a late teennote specifically, the pony equivalent of a college student and child respectively, and that's not even going into the newly-made or millennium-old question with Nyx. And things get even weirder when Nyx is artificially aged up to an adult horse...