Typically, a clone is made to be exactly the same as the original, and that includes the biological age.
How this is accomplished depends on how it gets created. Magical cloning tends to match the age by default, while more scientific methods will usually have to artificially accelerate the aging process.
Sometimes, though, intentionally or not, a clone is younger than the original.
Reasons for this vary. The simplest is that the clone's creator simply lacked the means to make them older. This especially makes sense in the case of scientific clones, since those generally start out as a zygote like everyone else, and there is no real-world way to freely accelerate growth — all real-life clones are this by default, being essentially identical twins born with a long delay.
If intentional, it could be that the creator wanted to replicate the original in their prime, particularly if they're meant to be a Human Weapon. A clone who is Raised as a Host or as a Walking Transplant is also likely to be younger than the original.
If the clone and the original become Artificial Family Members, the nature of their relationship will usually depend on how big the age gap is. If the age gap is large, they will probably take on a parent-child dynamic. If the age gap is small, they will probably be more like siblings.
On the other hand, sometimes the original may be hesitant to accept a younger "family member" suddenly thrust onto them.
Note that this is specifically for clones who are physically younger. By definition, all clones are chronologically younger than the original. Some works may have a clone be treated as younger due to them being chronologically younger, even if they're physically the same, but that's not this trope.
Examples:
- In Astra Lost in Space, all the main characters are younger clones and Artificial Family Members of body-snatchers wannabes, and one is even actually a clone of another clone, as they discover when doing DNA tests. Yes, this is going insane.
- Choujin X: Towards the end of the Great Choujin War, Queem Macman saw that his defeat was imminent, and so he used his powers to impregnate himself and give birth to several clones of himself which could hypothetically be used as a vessel for him to inhabit. It isn't known if Queem was able to transfer his consciousness in the end, but the clones in question would go on to live out endless cycles of "resets" in which they die and return to being a baby with an entirely new consciousness. In actuality, Azuma Higashi is merely the current consciousness of one of these mass-produced clones. His entire life and family were a lie that he deluded himself into believing to cope with how utterly alone he truly is.
- Code Geass: Rozé of the Recapture: In the final act, it is revealed that Norland von Lunebelg is actually a younger clone of the late Emperor Charles zi Britannia, who was initially made as a Body Backup Drive in the event of Charles' death.
- Demon Slayer: Kimetsu no Yaiba: Hantengu himself looks like an old man, while his Kidoairaku Clones look more youthful, to the point where the strongest, Zōhakuten, looks like a child.
- Lyrical Nanoha:
- Magical Girl Lyrical Nanoha: Fate Testarossa is eventually revealed to be a clone of Alicia Testarossa, Presea's daughter, born in 0034, meaning that the former would have been 31 in the series, at which point Fate is just 9. This point is moot, however, since Alicia has died aged just 5 and never met her clone-sister, except in alternative timelines.
- Magical Girl Lyrical Nanoha StrikerS features a much straighter example with Subaru and Ginga Nakajima, who are more-or-less direct clones of their adoptive mother Quint, produced illegally and without her knowledge using her stolen genetic material. Furthermore, Subaru was cloned two years after Ginga, creating an age gap between the sisters, as well. To complicate matters even further, Nove, one of the Arc Villain's Quirky Miniboss Squad, is a clone of Subaru herself, produced two years after her, meaning that there are three clones of Quint (though she has never met the last one before her death), each younger than her and also two years apart in age.
- Mobile Suit Gundam SEED: This is one of the big reveals during the last episodes of the series — Rau Le Crueset is the clone of Mu La Flaga's father Al Da Flaga. Al, being a very vain man, wanted a clone of himself as he believed Mu was "inferior" due to inheriting his mother's genes. However, because Rau's telomeres were the same length as Al's were when he was created, Al discarded him as another failure. Rau took his revenge by setting his home on fire, killing both Al and his wife.
- Neon Genesis Evangelion: Rei Ayanami is a teenage clone of Yui Ikari with a bit of Lilith mixed in. Rei seems vaguely aware of what she is, as she states at one point that if she dies, she can be replaced (which she is and in short order). It's implied that it's the same soul used between active clone bodies, but the process of transferring the soul to a new body seems to wipe out recent memories.
- One Piece:
- The Seraphim are clones of the original 7 Warlords that are significantly younger than the originals, as all the Seraphim are prepubescent (but still deadly, though), while the originals are all adults of varying ages.
- It's revealed in the Egghead Arc that CP-0 agent Stussy, is a clone of the former Rocks Pirates member Buckingham Stussy. She was the first successful clone made by Doctor Vegapunk, and is much younger than the original, who is now an old woman while Stussy is a young lady.
- Dog Man (Dav Pilkey): In "A Tale of Two Kitties", Petey the Cat clones himself with the intent of making his duplicate into his butler, but the result is a kitten that resembles his younger self (he didn't read the final step of the instructions for the cloning machine he bought that said it takes 18 years for a clone to reach adulthood). The clone calls himself Lil' Petey, and after getting him back from Dog Man, who took in Lil' Petey after Petey kicked him out of his house, Petey decides to raise Lil' Petey as his son, and as the story series progresses, the kitten is the main reason Petey has mostly reformed from his villainous ways.
- Fantastic Four: The supervillain, the Wizard, created several adult clones of himself. He also created one clone of himself as a child to be his son, and named him Bentley-23.
- Judge Dredd: This is the default for clones in the setting. The cloning technology developed by the Justice Department involves developing embryos in pods to artificially age them up to about 6 years, but from that point onwards, they age like normal humans. Dredd and his brother Rico are younger clones or "sons" of Chief Judge Fargo. There's another Fargo clone who took up Rico's name after his death but is again several decades younger than Dredd himself (their relationship has more of a Practically Different Generations older brother-vibe than a real father-son one). Dolman is yet another, even younger clone. This will likely continue, since there is an ongoing project to clone Dredd as well.
- Legion of Super-Heroes: During the "Five Years Later" era, a group of clones of the Legionnaires known as "Batch SW6" are discovered with the Dominators. They even included clones of fallen heroes such as Ferro Lad. During the "End of an Era" storyline with Zero Hour: Crisis in Time!, it's revealed that they are actually temporal clones created by the Time Trapper to try and save the timeline and let the 30th century exist in some way.
- Superman:
- The Conner Kent Superboy is this. He was originally meant to be older, but he was broken out by the Newsboy Legion as a teenager.
- Lex Luthor did this to himself — dying of Kryptonite poisoning, he pulled off a Faking the Dead scheme, then had scientist Dabney Donovan create a younger, stronger clone of himself to portray himself as the illegitimate son of himself and one of his doctors.
- X-Men:
- Laura Kinney is the younger Opposite-Sex Clone of Logan, created to serve as an assassin for hire. She was a teen/young adult when she first debuted in the comics, which is actually older than her first appearance in X-Men: Evolution. Of course she is still substantially younger than Logan, especially since he's much older than he looks. Logan is initially fairly distant with her, but eventually they start considering each other to be their father/daughter. Later, it's discovered that Laura isn't his clone but his actual daughter.
- Later Laura discovers that a company named Alchemax has made several clones of her, apparently to serve as bodyguards. Laura and the clones all consider each other sisters. In particular there is Gabby, who is significantly younger than Laura and the other clones, and the only one who has mostly kept her childlike innocence. Unfortunately, while Laura does her best to protect them, most of the clones die. Gabby survives though, and lives with Laura as her younger sister from then on.
- Magneto has his own younger clone in the form of Joseph, who was grown to his prime. However, because he doesn't have the same restraint Magneto has with his powers over a lifetime of usage, his powers are more unrestrained.
- An Adventure Too Weird For Words (DuckTales 2017): A variant; after coming in contact with an ancient relic, Louie ends up in an alternate dimension that's not only several years ahead of his own dimension, but is a world where he was killed by Scrooge's enemies years before. Thus, the family of the second dimension basically see him as a younger clone of the Louie they would've had (though they still treat him with all the love and respect a family member deserves).
- A Bat's New Bird: During the Halloween attack on Gotham, Robin fights a clone of himself that looks a few years younger physically and dissolves after losing. A talk between Talia al Ghul and her lead scientist both reveals why this happened and justifies this trope: cloning a human is already a tricky process, but artificially aging a clone puts too much stress on them, to the point that they can die of cellular degradation (which is what happened to Robin's clone).
- Spider-Ninja: After Shredder steals a blood sample from Spider-Ninja, he clones himself and uses the blood to give the clone spider powers (though without the spider-sense, to his disappointment). The resulting Opposite-Sex Clone is Karai, who is physically seventeen in her first appearance (much younger than the middle-aged Shredder).
- In With Strings Attached, the four find themselves on another planet, C’hou, 16 years younger (it’s 1980). Eventually they learn that the Fans cloned their normal Earth bodies, grew them to their 1964 ages, and transferred their souls into them.
- In The Boys from Brazil, Hitler is cloned by Nazi fugitives in South America: all these clones are then adopted as infants into families throughout the Western world, and the adoption agency specifies that father must be a minor civil servant, attempting to recreate Hitler's childhood.
- Gemini Man: Aging government hitman Henry Brogan discovers that the assassin sent after him is one of these.
- Logan:
- Just like in the comics, Laura is Logan's younger Opposite-Sex Clone, created to serve as a Human Weapon. The age gap is more extreme here though. Laura is a tween like in her first appearance in X-Men: Evolution and Logan is at the end of his extremely long life. Like in the comics, Logan is initially hesitant to accept the responsibility of looking after Laura, only coming around towards the end of the movie. Unfortunately, it comes a bit too late, as he dies soon after.
- The movie also has X-24, a perfected clone of Logan. Unlike Laura, X-24 is male, and aged up to match Logan's prime. This makes him a very dangerous opponent for the real Logan since he's well past that.
- Star Trek: Nemesis: the Reman Praetor Shinzon is supposed to be a physically younger clone of Captain Picard.
- Star Wars: Attack of the Clones: Bounty Hunter Jango Fett's genes are used by the Kaminoans as the base template for the Republic's clone army. As part of his compensation, he requests an unmodified clone of himself who isn't rapidly aged like the rest of the clone soldiers, and whom he can raise as his own son. The boy grows up to become Boba Fett from the original trilogy.
- Ultraviolet, the mysterious young boy simply known as "Six" turns out to be a clone of Big Bad Ferdinand Daxus, artifically bred to be a a carrier of a deadly virus.
- A Certain Magical Index: The Misaka Sisters are a group of 20,001 clones connected together by a hivemind. They were based off Misaka Mikoto, and created to serve as combatants in a series of death matches. For that purpose, the majority of them were aged up to match the original's age. The sole exception to this is Misaka 20001, more commonly known as Last Order. Instead of fighting, Last Order was created to serve as the Hive Queen, thus it didn't really matter how old she was. Physically, she is about 10 years old, 4 years younger than the original. Despite the fact that the hivemind should make her at least as mature as the other Sisters, she usually acts like a normal childish 10-year-old, although she does have a few moments where she shows that she's more intelligent than she seems.
- Vorkosigan Saga: Clones in this universe are science fiction but not magical, and therefore are younger than the "parent" by default. For one use case of cloning this is considered a feature, not a bug: On the planet Jackson's Whole you can get a clone made of yourself, then when it's old enough (this does involve a certain amount of forced aging, but is still a process that will take years) you scoop out your younger identical twin's brain and replace it with your own brain. Presto! You are now that many years (or decades) younger! (On most planets this is considered to be murder and is highly illegal.)
- Astrid: The resolution of "Immortal" involves The Reveal that the Body of the Week's son is actually his clone, originally meant to just be a Walking Transplant but then adopted after the "father" had a change of heart about the infant's fate. The decedent was in his fifties; the clone is 20 and Secretly Dying of cancer.
- Doctor Who: "The Doctor's Daughter" has Jenny, an Opposite-Sex Clone of the Doctor. She's played by Georgia Moffett, who's 13 years younger than David Tennant; as the episode's title suggests, she's treated like his daughter rather than a twin sister.
- Mutant X: The third season ends with the heroes meeting the mysterious leader of an Ancient Conspiracy, an old, white-haired scientist in a wheelchair. His face is that of Adam, the heroes' leader, who was created to complete the leader's work.
- Orphan Black: Most of the Project Leda clones, including Sarah, Allison, and Cosima, are in their mid-to-late 20s, but Charlotte Bowles was born only 8 years prior to her introduction. The woman they're cloned from is considerably older than any of them – she's Siobhan's mother and thus Sarah's adoptive grandmother.
- In Orphan Black: Echoes, Lucy and Jules are both clones of Eleanor, a scientist who died a few years before the start of the series, brought back at different points in her life in an attempt to evade the Alzheimer's that caused the original Eleanor's death. It later turns out that there's also another Eleanor clone that's closer to the original's age, and that the unscrupulous scientists who created Jules have been creating other teenage clones of other dead geniuses as part of a mad plot to seed the next generation of super-geniuses.
- The Pretender: The series opens with Jarod having escaped The Centre as an adult, and the organization doing their best to re-capture him. Late in the third season, they resort to using some of his DNA that they'd kept in their laboratory to create a clone of him, called Gemini. The clone is played by one of the young actors who portrays Jarod as a youth in flashbacks. He appears so stunningly identical that, to Jarod, it's like looking back in time at himself.
- Stargate SG-1: In "Fragile Balance", Colonel O'Neill appears at first to have been de-aged into a teenager, but it turns out that a rogue Asgard abducted him and replaced him with a clone. The clone was supposed to be advanced to the same age as the original, but Thor added some safeguards to O'Neill's genome to prevent that kind of thing.
- Dungeons & Dragons: In some editions, this is an advantage or disadvantage of the spell "Clone", which grows a Body Backup Drive that the subject's soul transfers into upon their death.
- 1st and 2nd Editions: The clone is a physical and mental duplicate of the subject as they were when the flesh sample was taken. If the flesh was preserved for a longer time, this could produce a clone with a new lease on life but at the cost of their memories and character levels.
- 5th Edition: The spellcaster can choose to make the clone as a younger version of the subject's body, providing a straightforward (if high-level) exception to the game's usual Immortality Immorality stance.
- AI: The Somnium Files - nirvanA Initiative: Late in the game, it is revealed that Mizuki Date is a genetically-modified clone of the six year older Mizuki Kuranushi, both having been created as part of Horadori Institute's unethical human experiments. This reveal plays heavily into another reveal regarding the order of events in the story, with some sequences having the player actually control Mizuki Kuranushi six years ago instead of Mizuki Date in the present.
- Fallout 4: Exaggerated; the child Shaun that the Sole Survivor has been pursuing turns out to be a synth version of the actual Shaun, who's aged into an old man by the events of the game due to being abducted decades prior to his parent leaving Vault 111. Since child Shaun is a synth rather than a regular clone, he will not age and remain a child for as long as he lives.
- Fate/Grand Order: Leonardo da Vinci takes the form of an adult woman. Her clone and backup body is that of a child.
- Goodbye Deponia: When Rufus discovers cloning facility in which he was created, it's stated that all clones are by default babies and to make them older is used nucleic acid. When Rufus later tries to clone Goal (actually Donna) he forgots it and because of that her clone is a little baby.
- Horizon Forbidden West: Seems to be the case with Aloy and Beta. Both are clones of Elisabet Sobeck, and based on plot cues Beta was probably created later, but the exact age difference between them is unclear. Elisabet Sobeck was in her late 40s at the time of her death, while both Aloy and Beta are teenagers. Depending on unknown variables, the difference could be a couple months or as much as five years.
- The Sims 3: This can be done in two ways, each from a different expansion. Generations allow Sims to use their lifetime happiness to get a clone voucher, which they can bring to the science lab, where they can redeem it for a child-aged clone of themselves (who will also be marked as their offspring). The University Life Expansion meanwhile adds a science skill, one of the features of said skill being cloning. Initially, they can clone collectibles (bugs, gemstones, and the like), but at a high skill level, cloning people becomes possible, the clone coming out as a newborn baby (and considered as not being related to anybody).
- Scoob and Shag: Shag discovers that he is only a Badass Normal clone of the original Shag, who died years ago. The reason that Shag doesn’t have powers is because there is still one chronologically and physiologically older clone left alive, and so the original’s powers have passed on to that clone instead of him.
- Torchwood (BBC Audio): In "Hidden", Tosh finds a mysterious photo of adult billionaire Sir Robert Craig beside a young child who looks like him. It soon turns out that the child is Robert's clone — Robert, who in reality is the Long-Lived Thomas Vaughan, created the clone in an attempt to produce an immaculate child conceived without conception.
- American Dad!: In "Steve and Snot's Test-Tubular Adventure", Steve and Snot decide to clone dates for their school dance that they can lose their virginity to. After going through the trouble of getting DNA samples, they use CIA technology to clone them, not realizing that the clones have to age up, starting off as infants. The two clones end up in a finishing school run by one of Roger's personas, with Steve and Snot acting as parental figures to them.
- The Batman: The Animated Series episode "House and Garden" has Poison Ivy supposedly retired from crime and living Happily Married with two adopted children. In reality, the real husband is locked away, and the family is all half-plant clones of him at different stages. We also see a few baby clones being "born".
- One episode of Buzz Lightyear of Star Command has Zurg creating evil clones of Team Lightyear but in his eagerness to use them, he takes them out of the generation machine too early, and they turn out to be children who cause him all sorts of trouble. Inverted at the end of the episode, when after Zurg tries to avoid making the same mistake by leaving a new set of clones in for a much longer period of time, they come out elderly.
- Danny Phantom: Dani Phantom is this combined with Opposite-Sex Clone, due to Vlad working with incomplete ectoplasm while creating her. Ultimately, she is seen as a failure prototype, as Vlad was trying to clone Danny more exactly to serve as his surrogate son.
- DuckTales (2017): At the very end of the series, it's revealed that Webby is an Opposite-Sex Clone of Scrooge McDuck himself. Because she's a child and he's over a century old, they quickly develop a parent-child relationship (with Webby readily/happily calling him "dad").
- Futurama: Cubert Farnsworth is the 12-year-old clone of Professor Farnsworth (who is 150 years old), created as his successor.
- Kipo and the Age of Wonderbeasts: According to the showrunners, many of the scientists in the DNA Burrow (the burrow where Kipo was born) are clones of previous scientists to keep the population under control. This includes Lio and Song Oak. This is not brought up within the show.
- The Owl House: Hunter is revealed to be only the latest of Belos' attempts at cloning a perfect version of his older brother Caleb, whom he murdered for falling in love with a witch. However, while Caleb was an adult when he died, Hunter is a teenager, and Word of God is that Belos deliberately raised him from childhood in hopes that a younger Grimwalker would be easier to mould after the adult ones betrayed him.
- Rick and Morty:
- In "Big Trouble in Little Sanchez", Rick clones a teenage version of himself, which he dubs "Tiny Rick", and transfers his consciousness into the clone's body so that he can hang out at his grandson Morty's high school.
- In "The Ricklantis Mix-up", one of the Ricks in the Citadel creates a baby clone of himself so that Candidate Morty can kiss it.
- Tangled: The Series: As a result of his Heroic Blue Screen of Death due to Cassandra turning evil, the Captain goes to Turapi Island and uses its magic to create a clone of his daughter. Due to his specifically wishing for the days when she was a child, the copy is a four-year-old Cheerful Child.
- X-Men: Evolution: In the episode "X23" Wolverine gets called in by SHIELD after a female assassin breaks in and steals files on him. It's soon revealed that she's actually a younger Opposite-Sex Clone of Wolverine, seemingly in her tweens/early teens. She was created by HYDRA to be a Human Weapon and "raised with love", but apparently escaped and is acting on her own initiative. She ends up attacking the X-Mansion, apparently blaming Wolverine for her miserable life up until then. After a brief fight, Wolverine is able to get through to her and lets her escape when SHIELD arrives. Later, X-23 gets brought into the comics, and gains the civilian name "Laura Kinney".
- Young Justice (2010): Just like in the comics, Connor Kent aka Superboy is a teenage clone of Superman created by Cadmus. He was created to either replace Superman if he died or take him down if he turned evil. When Superman finds out about him he is initially put off by the idea of having a clone and tries to avoid dealing with him as much as possible, instead leaving him in the care of Batman. This causes Superboy a lot of angst, Because not only is Superman the closest thing he has to a family member, he was also raised to idolize Superman. Batman attempts to convince Superman that he has a responsibility to look after Superboy, but it doesn't get through. Following the Team saving the Justice League in the season 1 finale, and the time skip between seasons 1 and 2, Superboy and Superman's relationship has improved dramatically. They now treat each other like proper family members, although it's a brotherly relationship instead of the father-son dynamic you might expect.

