It Runs in The Family

""Insanity runs in my family. It practically gallops.""

- Mortimer Brewster, Arsenic and Old Lace

A family full of eccentric, weird and sometimes insane relatives. Preferably all of them, but as long as it's the majority of them then it's okay. Commonly it's all of them except one perfectly normal one.

Someone may observe their... "activities", but when they confront the family about this, the said family will often have no idea that they are considered to be out of the ordinary.

See also Big Screwed-Up Family. In the Blood is the darker version of this. Contrast Turn Out Like His Father.

Anime and Manga

 * The Trinity siblings/Gundam Thrones. of Gundam 00 Michael is Ax Crazy, Nena's Cute and Psycho and Johann is The Stoic: they believe they are creating a better world... despite the fact they attack non-active militants and innocent civilians. As do the protagonists, for that matter, only they at least try to involve the civilians less.
 * The hero's three sisters in Magikano.
 * Gundam X's Frost Brothers, Shagia and Olba.
 * The Toguro Brothers from Yu Yu Hakusho.
 * The Rozen Maiden dolls.
 * The Kunos in Ranma ½ are all totally bonkers. In the manga (the story wasn't converted to the anime), it's revealed that having No Sense of Direction is something that runs in Ryoga's family—his mother and father are just as bad as he is. Some fans have even theorized that his parents are brother and sister due to this.
 * Bleach: Father and son Isshin and Ichigo Kurosaki, as well as Father and son Ryuken and Uryu Ishida.
 * The Ushiromiyas. Kinzo is dangerously insane, Eva is a Rich Bitch who, Rosa is an abusive single mother, and her daughter Maria is an extremely Creepy Child who may give her grandpa a run for the money in the "crazy" department. is downright delusional, . The rest are also neurotic, just less... violently so. Oh, and  of Kinzo's descendants have been seen to use magic, if you take the Anti-Mystery perspective. It's more than dysfunctionality and Cute Little Fangs that runs in this family.
 * Even the at least vaguely sane Battler is
 * Anyone, anyone, in A Certain Magical Index who is in any way related to the Kiharas can be easily identified not only as evil scientists, but as batshit insane, downright monstrous evil scientists.
 * Even the loli?
 * Apparently Chick Magnet runs in the Kamijou family.
 * Code Geass: Everyone- "everyone"- on the show arguably  by the end, but the Emperor's line is the most screwy of all, in both mind and manipulation. This troper cannot start listing examples, simply because everyone is an example.
 * Lelouch. Schniezel.   They're all well-intentioned extremists bent on taking over the world for the greater good. It most definitely runs in the family.
 * Q.E.D.: Touma's family are in general Cloudcuckoolander and are geniuses in one field or another.
 * Though we've only seen the female half of the Saginomiya family in Hayate the Combat Butler, they're all pretty well Cloudcuckoolander. Isumi is the closest one to sane, and she barely qualifies as such.
 * Isumi's grandmother mistakes her daughter, Isumi's mother, for Hayate when meeting him for the first time. And the mother thinks she actually is! Even wondering where she went when the grandmother changes paths.
 * Fullmetal Alchemist: THE LARGE HAMMINESS, SUPER STRENGTH AND THE SPARKLES OF THE ARMSTRONG FAMILY HAS BEEN PASSED DOWN FOR GENERATIONS!!!!
 * Ore no Imouto ga Konna ni Kawaii Wake ga Nai!: Both Kirino and Kyousuke are Tsundere in their own ways. However, both of them clearly get it from their father.
 * Shinichi's father in Detective Conan is a mystery writer who doesn't investigate because he's Brilliant but Lazy. Fellow detective Heiji's father is a well-known police investigator. Haibara's parents are scientists.
 * Inuyasha: Compassion for humans is rare amongst Youkai and it tends to cause trouble. Most Youkai kill or even eat humans instead of protecting them. Sesshoumaru originally states Inuyasha's human mother infected their father with weakness and Inuyasha must have inherited his compassion from her since Sesshoumaru doesn't have any. Myouga later clarifies that Inuyasha's compassion actually comes from his father. Eventually, it becomes obvious that Sesshoumaru's not as immune as he thought, culminating in his mother observing that his compassion for humans has turned him into his father. It would seem this compassion does run in the family resulting in Inuyasha and Sesshoumaru being Not So Different, after all. And, by Youkai standards, that actually makes them fairly eccentric.
 * For Kakuma Keita in the anime adaptation of Inazuma Eleven, being a Large Ham Announcer runs in the family. It helps that his father is a professional TV announcer for soccer matches.

Comic Books

 * The House of M, currently made up of Magneto, Quicksilver, the Scarlet Witch, and Polaris (probably), All of them pretty much known for periodically leaving their sanity at home. The third-generation kids may or may not be affected, but so far they're... mostly doing well.
 * Except for the ones who may or may not have just been a physical manifestation of Wanda's psychosis.
 * Oh, and the one who's currently being treated for an addiction to the Inhumans' Terrigen Mists.
 * Which her father got her hooked on after taking a few hits himself.
 * In All Fall Down, IQ and IQ Squared are both lonely, brilliant, irritable men who find it impossible to talk to each other.

Film

 * Loz, Yazoo, and Kadaj from Final Fantasy VII: Advent Children. Like their Father, they all want to help their Mother Jenova in whatever they can. If that includes threatening Formerly Corrupt Corporate Executives, Kidnapping Children, and summoning a Dragon to destroy a City, all the better!
 * They actually got that from their "Father" Sephiroth who burned down a village, stabbed a flower girl to death, and attempt to summon a giant Meteor to start a Family Barbecue for his Mother "Jenova". Yes, both Sephiroth and the three remnants have the same mother. Yes, Sephiroth is also their "father". You may get the Brain Bleach now.
 * What about Hojo, Sephiroth's Father? He may have even more atrocities then all of his sons and grandkids put together, if only for being the CAUSE of all of them in the first place.
 * You're all forgeting about the Mother's Side of the Family! Jenova likes to imitate Dead People, then Mind Rape anyone who's fooled by them so she can make them do her bidding so she can Eat the Planet's Lifestream! Too bad she's crippled and has to rely on her kids and husband to do all the dirty work after being smashed by a Meteor herself.
 * The Family Firefly from House of 1000 Corpses and The Devil's Rejects.
 * The Brewster family in Arsenic and Old Lace. The one family member who's not insane, murderous or both is Mortimer.
 * The Merrye clan of Spider Baby, who suffer from a degenerative disease that causes them to become murderous, insane cannibals. Played for nervous, squicky laughs.
 * The Portokaloses of My Big Fat Greek Wedding.
 * The House of Yes only shows four members of the Pascal family but they all have some severe issues. Not to mention that it is hinted that

Literature
"Cordelia: Counts Vorkosigan have come to horrible ends throughout your history. You've been blown up, shot, starved, drowned, burned alive, beheaded, diseased, and demented. The only thing you've never done is die in bed."
 * Inverted in A Series of Unfortunate Events: the Baudelaire siblings are the only people who aren't insane, evil, or completely oblivious.
 * The Bagthorpes, in the children's novels by Helen Cresswell (they start with Ordinary Jack). Tess, Rosie and William are all somewhat eccentric, and their parents and grandparents might edge into mildly deranged, as might their cousin Daisy... They all (well, except Daisy) believe wholeheartedly in their genius as a family and individually, and take themselves very seriously. In one of the books in the sequence, they try to break as many Guinness World Records in a summer as they can...
 * And in keeping with the trope, Jack and his ally Uncle Parker are the only sane ones people can bear to have anywhere near them. Also Grandpa (though he's less developed as a character).
 * Arguably, the Weasleys from Harry Potter are one big kooky red-headed family who are implied to be quite old and presumably extensive, as females are very rare in their line. There's only one Squib, who Ron reveals to be an accountant.
 * How about the Black family? All of them except for Sirius, Tonks and Andromeda are completely insane.
 * Regulus found sanity in the end.
 * Regulus worked his way up through the Death Eaters and betrayed Voldemort in the end. Heroic, but not necessarily a sign of sanity.
 * And actually, Sirius isn't all that sane either, though his slight insanity may be more due to having spent twelve years in Azkaban than anything else.
 * The Vorkosigans:


 * Count Piotr, the guy Cordelia was talking to and the 10th Count Vorkosigan, was the first to actually accomplish that last one: dying in bed at an advanced age. Miles Vorkosigan (whom his mother explicitly does not think is sane) has also got a lot of other crazy people in his family tree, especially from the Vorrutyer and Vorbarra branches of the family.
 * Subverted in the Doctor Who Eighth Doctor Adventures novel The Taint: Fitz's maternal relatives are mostly more or less insane. It turns out it's due to alien brain slugs, which the Doctor deals with. It seems, however, that Fitz has a slightly different view of matters, as in one or two later stories, he thinks he's hallucinating and blames it on the craziness that runs in his family, even though he hasn't got a brain slug any more. Naturally, he's not hallucinating.
 * The Pendergasts, in the thrillers of Douglas Preston and Lincoln Child, have a strong streak of insanity in the family. Sometimes this takes the form of a brilliant, unorthodox approach to investigating crime. More often, it takes the form of finding novel ways to wipe out humanity.
 * The Smedry family of the Alcatraz Series, in addition to having hereditary magical talents, have a reputation for extreme eccentricity.
 * In G. K. Chesterton's The Man Who Was Thursday, it's mentioned in passing that Syme grew up in an extremely odd family and eventually got so Bored with Insanity that he rebelled by being as sane as humanly possible. In fact, he's so sane that he's almost too sane, and therefore, in his own way, just as crazy as the rest of them.
 * The Woosters in Jeeves and Wooster are a pretty eccentric bunch in general, and at least one (Henry Wooster) spent his last days "in some sort of a home". For this reason, the "nerve specialist" Roderick Glossop has latched onto Cloudcuckoolander Bertie Wooster as insane and potentially dangerous.

Live-Action TV

 * The Addams Family.
 * Arrested Development is about a family that has no idea how to live conservatively and act like decent human beings....except for Michael Bluth, who the family both counts on to keep them afloat and takes for granted.
 * The Munsters are all members of the Monster Mash and are considered weird... except for human-looking Marilyn - who was considered ugly by the rest of her family (though she shares some of the other members' inhumanness like her very low body temperature).
 * Pretty much any reality show that involves some sort of family member swap. The shows will always show families that have weird quirks and the person who is swapping into that family usually finds it disturbing.
 * The Winchesters in Supernatural. Hunting, making deals with demons...
 * LazyTown's Stephanie is the only character in the show who has bright pink hair. But according to her uncle, it's a trait that runs in the family.
 * Kenny's family in Kenny vs. Spenny are all pure evil. At one point the entire clan comes together to fake Kenny's mom's death and hold a fake funeral and going in mourning just to keep Spenny from winning a footrace.
 * Malcolm's family from Malcolm in the Middle fits this perfectly, in a beautifully dysfunctional manner.
 * The Pond family from Doctor Who is smaller than most examples, but has more wackiness than most small planets. Poor Rory seems to be the Only Sane Man, as his wife spent her childhood biting psychiatrists, his daughter is a self-proclaimed psychopath, and his son-in-law put the "crazy" in Crazy Awesome.

Music

 * Amanda Palmer's "Runs in the Family" describes people who have inherited various complications from their bloodlines (My friend has maladies/ Ricketts and allergies/ That she dates back to/ The seventeenth century) and goes on to talk about her own family.

Theater

 * The Sycamore family from You Can't Take It With You

Video games

 * Caulder/Stolos's "children" in Advance Wars: Days of Ruin/Dark Conflict. Cyrus is fairly levelheaded, but Penny/Lili and Tabitha/Larissa... notsomuch.
 * The Magus Sisters from Final Fantasy IV.
 * The Royal Family and all their Cousins/Second Cousins/Distant Cousins in Katamari Damacy.
 * The Sasaki family of the Metal Gear series have always been some Ineffectual Sympathetic Villains who had some toilet problem of some sort.
 * The. Von. Karma. Family. Although we're not sure what happened to the older von Karma daughter so she might be some variety of sane.

Webcomics

 * The River family from Irregular Elis. A spanish webcomic about a Badass Family of Superheroes with a lot of Hanna-Barbera influences.

Web Originals

 * In the TV Tropes original webseries Echo Chamber, Zack's entire family seems to be severely messed up.
 * Zack keeps a dead cat in a box.
 * His dad is a control freak who screwed up Zack's childhood, and keeps him forever at that level of emotional maturity.
 * His Uncle Bill insists on telling a story about how Zack once pooped himself while playing in a sprinkler.

Western Animation
"Izzy: Genius runs in my family. AND psychotherapy!"
 * Poopeye, Peepeye, Pipeye and Pupeye, Popeye's nephews.
 * Plus Junior from Popeye and Son. He has his father's love of spinach, the "tumor arms", and the speech impediment.
 * The eponymous family from the film Meet the Robinsons is all eccentric verging on insane.
 * In Avatar: The Last Airbender, the royal family of the Fire Nation have a tendency to be sociopathic nutjobs. For some odd reason it only seems to happen to one family member per generation.
 * Maybe it's a recessive gene?
 * Total Drama Island implies Izzy's family may be like this:

Real Life

 * Truth in Television. Families often have quirks others find weird.
 * A possible explanation for Michael Jackson's extensive plastic surgery is because he didn't want to look like his abusive father.
 * The Durrell family, if youngest son Gerald is to be believed, were all amiably eccentric, with a few downright barmy older relatives. See My Family and Other Animals.