Is That Cute Kid Yours

A character or pair of characters are seen with a kid and are asked if the child is theirs, even if, due to age, there's no way it could be.

Sometimes used as a way of showing that the "parents" are a compatible couple, but more often just for laughs. If the person in question is too old to be the parent, it may imply a compliment (even flirtation, if the person asking is of similar age).

Truth in Television, especially amongst siblings with a significant age difference.

May be combined with She Is Not My Girlfriend.

Anime and Manga
"Mimet: Oh...are these your sisters?
 * In Love Hina, Otohime Mutsumi asks if Narusegawa Mei (about 10 or 12 years old) is Narusegawa Naru's (17) and Urashima Keitaro's (20) child. Of course, Mutsumi acts rather dim much of the time.
 * In the Manga Naru also asks Keitaro, upon first meeting Sara, if she is one of his many lovechildren, or if he kidnapped her. She is just joking though.
 * Ironically, numerous people in Sailor Moon comment on Chibi-Usa (8, or 900+), depending on source) being Mamoru's (17-19) and Usagi's (14-16) child. The irony being she is their child... but not yet.
 * Chibi-Usa and Usagi have been mistaken for sisters more than once.

Mamoru: No. They are my future wife and daughter."


 * Also played with in R before Chibi-Usa showed up. They were taking care of a baby boy: Minako said called the kid "their child" in good tease spirits, but An/Natsumi was peeved. Also, Chibi-Chibi was sometimes mistaken as Usagi's little sister (and introduced as such, sorta. Ikuko says so).
 * People also often say that Usagi and Chibi-Chibi seem more like mother and daughter than sisters, though.
 * Ranma ½ has a unique variation where Ryoga (16) is turned into a five-year-old and mistaken to be his own son. Then again, they might have not jumped to that conclusion if Ranma didn't introduce him as such just to mess with him.
 * In Bleach, mortals sometimes pose this question to Rangiku Matsumoto concerning Toshiro Hitsugaya, the subversion being that not only is Hitsugaya Matsumoto's superior, they're both Really Seven Hundred Years Old.
 * On the other hand, Hitsugaya is canonically a child prodigy, and very young for a shinigami. It's easily possibly that Matsumoto is several times his age. The fact that he's her boss, and the more responsible of the two still stands, though.
 * In Gakuen Alice, Sakura Mikan asks the elementary-school-age Hyuuga Natsume if the 3-year-old Hijiri Youichi is his. Then again, Mikan's a little dumb.
 * Soukou no Strain has an interesting twist, although it looks the same as other examples of the trope. For one, the apparent 16-year-olds are technically much older due to a Techno Babble-explained paradox with sub-lightspeed travel. For another, the apparent little girl is Really Seven Hundred Years Old.
 * It's surprising for them in another way, since the little girl in question showed up at their table when they weren't looking.
 * Parodied in Sayonara, Zetsubou-sensei, the girls mistake Itoshiki's nephew for his son and proceed to accuse him of children neglect.
 * Understandable since the kid called Itoshiki "Dad" and asked for food when they first met. He also looks like a child version of Itoshiki right down to the glasses and fashion sense.
 * Possibly a variation: In Kyou Kara Maou a young girl shows up claiming to be Yuuri's daughter, and his fiance Wolfram flips out, thinking that Yuuri has "cheated" on him...without considering the fact that Yuuri is 15, and the girl is about 8.
 * In Tengen Toppa Gurren Lagann during the Hot Springs Episode, Kiyal asks Yoko (who she just saw a couple weeks ago, and who is 14 years old) whether Darry and Gimmy (who are about five to seven) are her kids. Cue Spit Take.
 * In the fourth volume of Kimi wa Petto (Tramps Like Us in English), Sumire and Momo are taking care of six year old genius for a few days and people in the park comment on cute those young parents are.
 * Used a bit more seriously in Bunny Drop, with the nearly-thirty Daikichi and six year-old Rin. A slight subversion in that Rin is biologically Daikichi's aunt.
 * To be fair, Daikichi is Rin's father figure and the person who raises her. The only reason he doesn't offically adopt her is because she didn't want to be.
 * In Gintama, Saa-chan mistakes the baby with Gintoki (who looks remarkably like him) to be his child with Otae, who just happens to be there at the time. It ends badly (for Gintoki). But the kid is really cute.
 * In the Yami no Matsuei manga, Tsuzuki meets Doctor Muraki in a Meet Cute version, when Tsuzuki catches a fainting little girl and Muraki treats her and asks if she's his daughter. Of course, as it's Muraki, it's a deliberately Invoked Trope.
 * In Honey and Clover, a ryokan receptionist asks Professor Hanamoto if the gang are here for a family reunion and if Hagu is the Prof's middle school age daughter (She isn't).
 * To Love Ru occasionally has people mistaking Celine for Rito's daughter (and whatever girl he's with as the mother). It's actually forgivable in this case, as Rito is 17, and Celine looks to be about 2, so it's actually possible. Of course, one of the people who makes this mistake is Rito's mother, who should know better.
 * Then again, similar to Bunny Drop, Rito is sort of her father figure.
 * Baby Be'el of Beelzebub is constantly mistaken for Oga's son. This is another occurence where it is a natural assumption. Oga is a 15-16 year old, while Beel looks a year old, or less. Plus, Oga is supposed to raise him, and they look very similar.
 * Aoi is often mistaken for her baby brother's mother whenever they go out. It really annoys her since the gossiping housewives think that she's an irresponsible teenage single mom.
 * One of the epilogue side-stories to Victorian Romance Emma shows that Grace Jones is occasionally mistaken for Colin or Vivian's mother. She does not take it well.
 * After the Lord of Terror arc in Ah! My Goddess, Megumi meets Skuld for the first time, and asks if she's her brother and Belldandy's kid. This despite the fact that Skuld is biologically around 12, and Keichii has known Bell for maybe a year and a half at this point.

Comic Books

 * In Elf Quest: Siege at Blue Mountain, Cutter pays a visit to the human couple Nonna and Adar and assumes that the three children living with them are theirs even though they are too old. His misunderstanding is due to the elves' low birth rate, and their general ignorance of human gestation periods and growth rates.

Fanfic

 * DC Nation: Troia was asked several times if Lian was "hers." Because of her Truth Sense, she would have to answer "no," but Lian would cheerfully answer "Yup!" Part because Lian cannot stand her super-villainess mother, and part because Donna's been "Mom...in all the ways that count!" They met half-way; Donna is now Lian's stepmother.

Literature

 * William Laurence gets subjected to an age-appropriate variant when he, Temeraire, several uniformed crewmen, and a twelve-year-old girl attended an Aerial Corps fundraiser. His father Lord Allendale, after the latter cheerfully admitted to Laurence and Temeraire personally tutoring her; cornered his son and quietly made diffident, embarrassed, and evasive inquiries as to the health of the young girl's mother. To deny an unspoken accusation would have made Laurence look even worse, he could not reveal her true status in public, and his attempt at a bare bones/true-as-far-as-it-went explanation ("She is the natural daughter of... a gentlewoman living in Dover, whose education I have taken as my charge") did nothing to allay suspicion.
 * Occurs in several PG Wodehouse stories.
 * More or less inverted in Twilight: the Cullen parents always present the teen vampires as their adopted children, because the ages wouldn't fit. Then Bella and Edward pretend they adopted Renesmee, because even assuming Bella and Edward had a shotgun wedding, it's impossible that Nessie to be born so soon when the pregnancy was not visible at the wedding.
 * Not to mention the fact that Edward wasn't even in the area during the time she should have theoretically been conceived.

Live Action TV

 * Lucy from 7th Heaven took the twins out for a stroll and was mistaken for their mother, which opened her eyes to the plight of single mothers.
 * Buffy was mistaken for Dawn's mother in the first episode of the seventh season of Buffy, "Lessons".

Video Games

 * Phoenix Wright. Pearl tags along with Phoenix and Maya, but whenever Maya is not present, some of the NPCs believe Pearl is Phoenix's daughter.
 * This is relatively (and scientifically) believable since Phoenix is in his mid twenties, while Pearl can't be older then around 8.
 * On the other hand, it works entirely backwards in Apollo Justice with Trucy, who says
 * Coincidentally Pearl and Trucy are the same age, so it's rather funny that Pearl would be mistaken for Phoenix's daughter, while Apollo doubts that Trucy is. Phoenix would've been 18 when they were both born.

Western Animation

 * Avatar: The Last Airbender: Sokka (15) and Katara (14) (who are actually brother and sister) pose as Aang's (12, or 112) parents when he enrolls in a Fire Nation school because he wants to be normal for a little bit and find out some things about the Fire Nation. They pull it off! All Sokka had was a fake beard/mustache and Katara just stuffed her shirt to make it looked like she was pregnant (or fat).
 * Fridge Brilliance: In a world where the average marriage age seems to be about 16, its a bit easier to accept that the school might not find Katara and Sokka's youth too unbelievable. Now, the fact that both of Aang's 'parents' seem to have a significantly darker skin tone then him on the other hand...
 * Maybe they thought he was adopted? There are a lot of orphans on this show...
 * In Family Guy, Meg gets mistaken for her brother Stewie's mother, and then goes along with it to get a job and tips.
 * And then Promptly gets Stewie taken away by Child Services when she fabricates hardships to increase her tips.