Manolito: HA! I would never take that kind of nonsense from my parents. Today I'd have a different family, a different face and a different surname, but I'd be born anyway, by God!
In layman's terms, a child still exists despite their parentage being altered or changed.
One possibility involves the Timey-Wimey Ball, where someone goes back to a time before they were conceived (or a Kid from the Future comes back to ours) and we find out that one (or both) of the kid's parents (or ancestors) are now completely different people. Despite this, either the current person remains mostly unchanged (aside from a few Ripple Effect Indicators) or they now have an Alternate Self that is still uncannily similar.
Another possibility involves multiple versions or multiple narratives of the same events, and despite different parents or ancestors getting together in each, it results in either the exact same children or Suspiciously Similar Substitutes.
The exact cause of these shenanigans can vary. Perhaps the past was changed, but someone did their best to ensure a Close-Enough Timeline and raised a child with the same name as the one they knew of in the future. Maybe time is just stubborn and some sort of contrived circumstances happened that resulted in a child being born with that name. Maybe it's a Bizarro Universe or Mirror Universe where similar events happened, but with slight changes or alterations. Or perhaps the solution involves clones or twins or even some kind of Fusion Dance, Grand Theft Me or other convoluted circumstances.
And of course, we can't rule out a Contrived Coincidence.
NOTE: Both ancestries must be part of the same narrative continuity. This trope does NOT include adaptations, retcons or reboots. Those are covered by Adaptation Relationship Overhaul, Unrelated in the Adaptation, Related Differently in the Adaptation and Related in the Adaptation; they don't apply unless one of the following also applies:
- It's later revealed that the different works take place in the same shared multiverse, or some other form of shared continuity.
- The work lampshades that the new child is an Alternate Self or copy-and-paste Expy of the original one, with the same name, looks, abilities, personality and/or narrative role.
- In Dual! Parallel Trouble Adventure, when Kazuki travels to an Alternate Timeline, most of the people he knew are still around, with the exception of himself for an unknown reason. This includes Mitsuki Sanada, who is instead named "Mitsuki Rara" in this world because in this world, her mother had a child with a different man. Rara's sweet personality is the polar opposite of Sanada's bossy Tsundere attitude, but the two look almost identical aside from having a different hair color and style. At the end of the series, the two worlds are merged and in the rewritten reality, the two Mitsukis are cousins instead, with their mothers being sisters.
- Played with in Jojos Bizarre Adventure. Part 7 introduces a new timeline and begins with very different versions of familiar characters. Johnny Joestar is, in many ways, a Foil to the original Jonathan Joestar. Further, Johnny marries into the Japanese Higashikata family instead of the English Pendleton family. However, according to a family tree shown in Part 8, Johnny's kid is still George Joestar II who still marries an Elizabeth, they still have a Joseph Joestar, who proceeds to marry a Suzi Q, who in turn have a Holy Joestar, even when some birthdates differ significantly. Just like with Johnny, however, the circumstances surrounding these events and characters can vary wildly from the originals.
- The Simpsons: In a one shot story from the comic, a mishap in professor Frink's lab resulting from one of his monkeys putting aluminum foil in microwave near some equipment leads to reality being warped, with Frink and a flying monkey being the only ones who know everything's changed. In this new reality, Bart and Lisa are in Mr. Bergstrom's fourth grade class but Lisa seems to be an only child as she's the daughter of Marge and her ex-husband Artie Ziff, while Bart is Maggie's older brother and they, along their father Homer, were abandoned by Mindy.
- Superboy: While the first Superboy is simply Superman as a child, every successor has been some variation of his offspring — both natural and otherwise. Conner Kent was revealed after a while to be a clone of both Superman and Lex Luthor. When the timeline was rebooted, he was replaced by a Superboy who was also a clone of Superman's son with Lois Lane, named Jon Lane Kent. Even later still, an Un-Reboot introduced Superman and Lois's real child, Jonathan Samuel Kent, and also brought back Conner. The entire basis of the House of Kent storyarc was dealing with the weirdness of having two Superboys with such similar but incredibly different origins existing at the same time.
- X-Men: Cable and X-Man are technically the same person, with the same father but two different mothers. Cable's mother is Madelyne Pryor, a clone of Jean Grey, while X-Man's is Jean herself. This has been nodded to in the past, with Cable referring to Nate (X-Man) as "my half-brother."
- Oversaturated World: Group Precipitation: In "Retroactive Discontinuity", Rainbow Dash has two possible mothers — Firefly, mentioned in a previous story, and Windy Whistles, from the source show. The fanfic, and therefore Rainbow Dash, has to choose between her possible mothers. She sticks with Firefly. That choice propagates backwards, Retgone-ing Windy Whistles, but Apple Bloom, effectively the Norn of the Past from Norse Mythology, saves her.
- Terminator: A common concept brought up in Expanded Universe works or speculated by fans is that John Connor was originally conceived by someone else and not the time-travelling Kyle Reese, in order to explain the Predestination Paradox of a man being sent in time to protect (and conceive) a person who originally didn't even exist. In one comic adaptation which resulted in an Alternate Timeline, John Connor was born a girl.
- Chrono Trigger:
- In one ending, Crono and Marle return home only to discover that people in the castle are strangely "ribbiting" like frogs. They decide to check some old tapes and find out that their ally Frog married Marle's ancestor, Queen Leene, resulting in Marle (and many other people distantly related to her) are now part frog, although they generally look and act exactly the same.
- One ending has the entire events of the game rebooted, with humans now replaced as the dominant species by Reptites (their world's equivalent to dinosaurs). Despite this, the world, towns and events are all identical to what they were originally, with Crono and Marle (also Reptites) pretty much replaying the exact opening events of the game exactly the same.
- Dragon Age: In Dragon Age: Origins, the Gray Wardens face a dilemma whereas one of them will have to make a Heroic Sacrifice; the only way to slay the Archdemon is if the Gray Warden that kills it also dies, as that will destroy the soul of both the Warden and the Old God inside the Archdemon. The witch Morrigan offers herself to be impregnated so that her child will absorb the Old God soul and spare any sacrifice. The player can choose to go through with it, choosing either himself (if male), Alistair or Loghain to do the honors. In later stories, we also learn that it's possible for a Warden that romanced Morrigan to have impregnated her with a normal child as well. In Dragon Age: Inquisition, we meet Morrigan's son, Kieran, who looks exactly the same no matter who his father was. He is even the same if he was raised by the player's original Gray Warden in a loving relationship with Morrigan. He does have some creepy, otherworldly abilities if he has the Old God inside him, but even that is relatively minor and otherwise, he is a perfectly well-behaved and pleasant child.
- Dragon Quest V: The Hero's children Parry and Madchen are functionally identical in personality (which makes sense as they only meet their parents later in life, having been raised by friends of the family after both parents are turned into statues), the only difference between the three versions is their hair color (blonde, blue or black), which they inherited from their mother (depending on whether you picked Bianca, Nera or Deborah to marry). Going by the official artwork, the Hero went with Bianca (and an Urban Legend of Zelda claimed that not choosing her in the very first version of the game caused Bianca's Death by Despair and limited Nera to a very low level).
- Fire Emblem: Taken Up to Eleven in Fire Emblem Awakening and Fire Emblem Fates, as every female character in the core cast plus Chrom and Male Robin in Awakening and every male character in the core cast plus Azura and Female Corrin in Fates has a set child that they can have with almost anyone (generally, the Player Characters can romance and have their opposite-gender child with any other character while everyone in the core cast can romance one another). All this changes is the respective child's hair color (in fact, the parent/child support is the same no matter who the other parent is) and the existence of a sibling in the cases of Lucina, Morgan, Kana, and Shigure should their respective parents achieve S-Support with someone with their own child.
- Played with in the Warlords of Draenor timeline of World of Warcraft. Despite it being confirmed that the timeline varied from ours even before the obvious Point of Divergence, it's still extremely close to ours when we get there and tends to coincidentally follow some of the same beats (including certain new family trees being retconned to be true of both timelines), despite drastically different circumstances.
- This is averted in the mag'har questline, taking place another 30 years down that timeline. In the main timeline, Durotan and Draka had a son, Go'el. In the alternate timeline, they had a daughter, Geya'rah, who is in many ways Go'el's opposite and can scarcely be considered the same character.
- Exarch Hellscream is a bit muddier. In a literal sense, he is an aversion, as his life has a very different path than our Garrosh Hellscream beyond being Grommash Hellscream's son (not even having the same mother). However, there are strong thematic connections. The questline reveals that in the greater multiverse, Garrosh usually turned out a hero. Exarch Hellscream fits in an interesting place within this pattern. Unlike ours, but like the rest of the Garroshs in the multiverse, he decided to do some good by joining the Lightbound to save Draenor and the fall of the rest of the universe. Like our Garrosh, the war is shown to be more than a bit misguided and making him a very similar conqueror as ours. It should also be noted that unlike with Geya'rah, we don't know Exarch Hellscream's given name (Exarch is a title).
- SHUFFLE!: In the sequel Tick! Tack! that follows Nerine's route from the original game and has Rin, Nerine, Mayumi, and Itsuki Time Travel to before Nerine's father Forbesii chooses his bride, the player's choices can change Nerine's mother from Sage to Ai. This also alters her physical features, personality, and memory.
- Homestuck: The Scratch creates an alternate timeline where the key Sburb players switch places with their biological parents. In spite of this, Dad Egbert/Crocker across the Scratch still appears to be the same across both instances, even though he would be the son of a different person as a result of the switch. Hidden lore from the "Skaianet Systems" website implies that he was a result of cloning from the same parents, but the lore was deleted for unrelated reasons and was questionably canon to begin with.
- Dragon Ball Multiverse: One of the spectators from Universe 9 (a universe where the Earthlings faced numerous threats without Saiyans or Namekians to help them) is a "different" version of Trunks, who is strongly implied (outright stated in the official novelisation) to be the son Bulma had with Yamcha instead of Vegeta, Trunks' father in other timelines.
- American Dad!: The Season 11/12 Christmas Episode "Dreaming of a White Porsche Christmas" has Stan's wish to have Principal Lewis's bachelor life fulfilled. In the alternate reality created by the wish, Francine married Lewis instead. They have children that look like Hayleynote and Steve but are half-black and have curly black hair.
- Bob's Burgers: In "Sliding Bobs", Tina imagines what things would be like if Linda had married her ex-fiance Hugo Habercore instead of Bob. The hypothetical Habercore children, along with having Hugo's blond hair, have personalities that are the opposite of the Belcher children: boy-obssessed Tina becomes Mona, who has no interest in boys at all; Large Ham Gene becomes shy, soft-spoken Dean; and tomboyish Enfant Terrible Louise becomes Charlize, an Adorably Precocious Child in a pink princess dress. The mere concept terrifies every member of the family, and Louise outright calls Tina a monster for reimagining history.
- Family Guy
- In one episode, Peter accidentally changes the course of history when he goes back in time and blows off a date with Lois. In the new timeline, Lois married Quagmire, and thus Meg, Chris, and Stewie were all fathered by him. They all share his nose, chin and libido.
- In "Chap Stewie", Stewie, tired of living in the Griffin family, goes back in time and breaks up his parents before he was conceived. Instead of no longer being born, Stewie is instead born as the son of rich British parents (He surmises that his soul was simply transferred to the next birth at that point in time).
- The Simpsons: In "Bart and Homer's Excellent Adventure", Bart goes back in time and ruins his parents' first meeting, ensuring Marge never falls for Homer. He initially fears that this will erase him from existence, but instead discovers that he, and his sisters Lisa and Maggie, are now the children of Marge's old boyfriend Artie Ziff (and have gained his hairstyle, to boot).