History Main / RoyalInbreeding

** The Targaryen dynasty wed [[BrotherSisterIncest brother to sister]] (not as often as you'd think, but likely more often than you want to imagine), [[KissingCousins first cousin to first cousin]] (most common), or even uncle to niece (occasional) for centuries, which is often blamed in-universe for their tendency to produce the odd [[TheCaligula mad king]] (mainly by those very strongly of the Faith and rather biased on the whole issue). It got to the point that Daenerys (the series's most prominent Targaryen) only has ''two'' great-grandparents rather than eight because her parents and grandparents were brothers and sisters. It's suggested that the Targaryens have some sort of strengthened genes because they are, for the most part, physically sound, whereas the extent of such inbreeding would be genetically disastrous if it is practiced in real life (Daenerys is more inbred than the infamous UsefulNotes/CharlesIIOfSpain). That said, many Targaryen kings did have to contend with higher-than-average rates of infertility and stillbirths, and plumbing the depths of Targaryen history will reveal more than a fair amount of royal children born with extra toes, webbed fingers, and scales... although that might also indicate that their claims to be "blood of the dragon," which such practices were meant to preserve, were NotHyperbole.

* ''Manga/{{Berserk}}'': According to the king's brother Count Julius, his son was to marry the king's daughter Charlotte when both came of age. This ends up not happening when [[spoiler:Guts is ordered by Griffith to assassinate Julius and accidentally kills Julius's son in the process when he reflexively attacks on realizing someone's seen him]].

* ''Literature/TheIrregularAtMagicHighSchool'' uses this trope as a sudden plot twist in the 16th volume when it becomes clear that [[spoiler:Tatsuya [[BrotherSisterIncest should become the future husband of his own sister]] so that his unique abilities remain forever in the clan. So, as his sister is a perfect {{Designer Bab|ies}}y, their siblings' marriage will not be dangerous for their children and eventually give their clan even stronger offspring than if she married another person.]] And although the rest of the magical world as a whole averted it (as mentioned, even a marriage between cousins is considered undesirable due to possible genetic problems), we learn that [[spoiler: Yotsuba]] is not the first clan that started experimenting with incest thanks to new opportunities offered by genetic engineering.

* Apparently not uncommon in the Juraian royal family in ''Anime/TenchiMuyo'', as Prince Yosho was engaged to his half-sister Ayeka prior to going AWOL (though it's suggested they didn't actually intend to go through with it and mostly arranged it to quiet potential objectors due to Yosho being mostly human, notably apparently no-one had a problem with the incest). And as part of the MarryThemAll solution to the main series' LoveDodecahedron, Tenchi could also potentially end up with Ayeka and/or Sasami, who technically speaking are his great-aunts.
** Due to a truly TangledFamilyTree, in most continuities Tenchi is (potentially) related to ''all'' of his would-be love interests. Though characterising the exact relationship between Tenchi and Washuu and her family (Ryoko and more distantly, Mihoshi) is tricky. Short version, Washuu is the sister of Tsunami, who is undergoing a long-term fusion with Sasami, one of Tenchi's aforementioned great-aunts. So in a way Washuu is Tenchi's great-aunt as well, ''genetically'' she is not since the relation is via [[FusionDance fusion]].

'''John Whipple:''' Damn it, Abner, every time you start an answer that way I know it's going to be irrelevant. Two of the most completely civilized societies we've ever had were the Egyptians and the Incas. Now, no Egyptian king was ever allowed to marry anybody but his sister, and if I can believe what I've heard, the same was true of the Incas. They prospered. As a matter of fact, it's not a bad system, scientifically. That is, if you're willing to [[BuryYourDisabled kill off ruthlessly any children with marked defects]], and apparently the Egyptians, the Incas and the Hawaiians were willing to do so. Have you ever seen a handsomer group of people than the alii?

** Despite this, however, the series hasn't actually provided an example of an outright incestuous couple; the closest are Sirius' parents, Orion and Walburga, who were second cousins, something that is not worth batting an eyelid in Europe. The Gaunts are mentioned to practise inbreeding, but we have no detailed genealogy to base this claim on.

** Cersei and Jaime Lannister are twins who secretly have an affair. They have three kids. The good news: the younger two are sweet kids, and seemingly okay! The bad news: The eldest is [[RoyalBrat Joffrey]] [[TheCaligula Baratheon]], who starts a three-way civil war with two secessions. Jaime and Cersei tried to justify their relationship by citing the Targaryen practice, but both felt great pangs of guilt wondering if their sin led to their thoroughly rotten eldest. Also of note is that Cersei's and Jaime's mother and father were [[KissingCousins first cousins]] who were both born with the name Lannister, although [[ValuesDissonance first cousin marriage is unremarkable in Westeros and isn't considered incest.]] Ned Stark's parents were first cousins once removed who were both born with the name Stark as well.

* ''TabletopGame/WerewolfTheApocalypse'': The Silver Fangs suffered from inbreeding despite their biological requirement to outbreed (Werewolf/Werewolf pairings always result in the sterile and deformed Metis no matter how closely related the parents are). They managed this by being so proud that they disdained marrying any humans that weren't royalty. So not only did they severely limit their pool of potential partners, they got ''all'' the RoyallyScrewedUp that resulted from ''previous'' inbreeding. Marrying into the Habsburg line was not very good for their genetic health.

* The practice of ''[[http://www.iranicaonline.org/articles/marriage-next-of-kin xwedodah,]]'' marriage of close family members to each other, in the noble families of Persia prior to the Arab invasion. Very little information about this practice has survived into the modern day (and it is not practiced by modern-day UsefulNotes/{{Zoroastrian|ism}}s), but it appears to have been a practice grounded partially in religion and partially in culture and was most likely restricted to royals and priests.

* Vittorio Emanuele III of Italy was infamously short and of poor health thanks to generations of cousin marriages among his ancestors finally catching up to his dynasty. He was perfectly aware of this to the point that as the heir to the throne, he torpedoed his possible engagement to a German princess precisely because they were related... Resulting in [[ShipperOnDeck literally all royals of Europe joining forces to insure he'd marry Elena of Montenegro]], to whom he wasn't related. His son Umberto II was much taller and in better health.

Oftentimes this is used to explain TheCaligula, RoyallyScrewedUp, and ItRunsInTheFamily. Might be used to justify a SingleLineOfDescent and LookalikeLovers. InbredAndEvil has an interesting relationship to this trope, as the attitudes that were used to justify inbreeding among nobles were pretty much the inverse, but it's also one of many allegations used to prove that AristocratsAreEvil.

* In ''TabletopGame/{{Ironclaw}}'' grey foxes, the ruling house of Calebria, often exhibit signs of inbreeding like hemophilia or color blindness, with rumors of more extreme traits like polydactyly.
** The novel ''Scars'' elaborates further, all grey foxes in Calebria are of House Rinaldi, and if they mate with the more common red foxes their offspring are usually red. The other major houses are the same species as most of their peasants so they have the option of legitimizing their bastards and adding some diversity to their gene pools.
* ''TabletopGame/{{Warhammer}}''

* The Navigator Houses in ''TabletopGame/{{Warhammer 40000}}'', aka the Navis Nobilite, tend to act like aristocrats and have become so inbred over the millennia that most if not all of them have mutations other than their genetically engineered third eye (which is recessive, hence the inbreeding).
* The Silver Fangs of ''TabletopGame/WerewolfTheApocalypse'' suffered from inbreeding despite their biological requirement to outbreed (Werewolf/Werewolf pairings always result in the sterile and deformed Metis no matter how closely related the parents are). They managed this by being so proud that they disdained marrying any humans that weren't royalty. So not only did they severely limit their pool of potential partners, they got ''all'' the RoyallyScrewedUp that resulted from ''previous'' inbreeding. Marrying into the Habsburg line was not very good for their genetic health.
* Notably averted in ''TabletopGame/DungeonsAndDragons'' settings like ''TabletopGame/{{Greyhawk}}'' and the ''TabletopGame/ForgottenRealms'', which contain almost no examples of royal inbreeding. Some of this may come from a lack of interest or knowledge among writers and players. An InUniverse explanation may be that, since many adventurers are everything from {{Impoverished Patrician}}s to [[SelfMadeMan Self Made Men]] or even peasants who achieve RagsToRoyalty, most aristocracies have semi-regular turnover and less stigma against marrying between classes. The Realms, in particular, also has many lands that aren't actually monarchies, so there's simply less chance of it happening.

* The House of Habsburg (originally from a part of the globe that would, interestingly enough, evolve into direct democracy Switzerland), which ruled large parts of Europe for several hundred years (with branches in Spain, Austria, and parts of Italy), was notorious for this: they acquired a lot of land through dynastic marriages and tried to avoid having the same thing happen to them by keeping things in house. The last of the Spanish Habsburgs, the infamous [[http://en.wikipedia.org/wiki/Charles_II_of_Spain Charles II]], was actually [[RoyallyScrewedUp more genetically inbred]] than a "typical" product of BrotherSisterIncest would have been thanks to generations of cousin/cousin and uncle/niece marriages. His health problems were so severe that even the royal portrait artists -- who were ''being paid'' to make him look good -- couldn't hide his very prominent lower jaw and strangely squashed nose. He has been described as ''"short, lame, epileptic, senile and completely bald before 35, always on the verge of death but repeatedly baffling Christendom by continuing to live."''[[note]]The French diplomat who had the unfortunate duty of fixing up Charles's first marriage said "he is so ugly as to cause fear."[[/note]]
** To put this into context, Phillip III was Charles II's grandfather through his father and his great-grandfather through his mother. Phillip III was related to his own wife, Margaret of Austria, in at least 6 ways (first cousins once removed, 2nd cousins through two different branches, 2nd cousins once removed through two different branches, and 3rd cousins) which made his relationship worse than a "typical" first cousin pairing. This came about because Margaret was the result of an uncle/niece pairing while Phillip III was a product of an uncle/niece (also 1st cousins once removed) pairing. Charles II's other great-grandfather was Holy Roman Emperor Ferdinand II. Ferdinand II was related to his own wife, Maria Anna of Bavaria, in at least 3 ways (1st cousins, 2nd cousins once removed, and 3rd cousins). Despite Phillip III and Margaret not being true 1st cousins, they were actually more closely related to each other than Ferdinand II was to Maria Anna. Phillip III's daughter, Maria Anna of Spain, and Ferdinand II's son, Holy Roman Emperor Ferdinand III, married each other (adding yet another 1st cousin connection into the mix). Phillip III's son, Phillip IV, then married the product of '''that''' incest, Mariana of Austria to add one last uncle/niece pairing into the mix. To get a good reference, it's scientifically recommended that you not are more closely related to your spouse than 3rd cousins to avoid most complications from incest. An uncle/niece pairing is already 32 times closer to each other than 3rd cousins are.[[note]]Phillip IV and Mariana would be at least ~46.6 times closer to each other than normal 3rd cousins would be. Theoretically, that's still not as bad as the "64 times" greater that would come out of parent/child or sister/brother pairings. That's how bad [[BrotherSisterIncest immediate family pairings are.]][[/note]]

* The Yayoi clan in ''{{VideoGame/Blaz Blue}}'' is one of the oldest members of the Duodecim, the 12 families that formed NOL. They put such an emphasis on preserving their magical abilities that when children who exhibited weaker ars magus aptitude started being born, members resorted to incest and inbreeding in the mad delusion they would get stronger, much to the disgust of the other families. It's specifically noted that Tsubaki isn't the firstborn child of her parents, she's merely the first to ''survive''.

* The ancient Korean kingdom of Silla (first millennium CE) had a strict bone rank system that determined one's social class. And only Sacred Bone, royal dynasty, could ascend to the throne. However, to be born as a Sacred Bone, one must have both Sacred Bone parents, which resulted in the royals marrying within the family. This bone rank system was so strict that when there were no more male Sacred Bones, the female Sacred Bones ascended to the throne, despite there being other males with royal blood, which was unbelievable to even think about during that period in that area. Marrying one's half-siblings was socially accepted and often happened, not only among royals but also among nobles and possibly among commoners.