When you hear the phrase “royal families,” you might picture glittering crowns, opulent palaces, and centuries‑long dynasties. Yet, behind the pomp, a shadowy tradition of close‑kin marriages has haunted many thrones. In this roundup of 10 royal families, we dive into the tangled, sometimes scandalous, incestuous practices that shaped their histories.

10 Royal Families and Their Dark Secrets

10 The Monomotapa Of Zimbabwe

Various African monarchies practiced dynastic incest, and the Monomotapa kingdom of Zimbabwe was no exception. Its rulers were fervent polygamists, with one monarch reputed to have amassed more than three thousand wives. Among this vast harem, his preferred consorts were his own sisters or daughters, and any outsider daring to court a royal wife or daughter faced certain death.

The incestuous custom of the Monomotapa is vividly illustrated by the legend of the Balovedu tribe’s Rain Queen lineage. The Rain Queen, a figure endowed with the power to summon rain or drought, is said to have first received her magical abilities when Princess Dzugundini bore a child with her brother—or perhaps her father, depending on the version—and was forced to flee amid public shame. Rather than execute both mother and child, the king granted the princess rain‑making powers and arranged her escape, cementing the incest tradition in mythic memory.

9 Cleopatra

Cleopatra VII remains one of the most recognizable rulers in Western history, immortalized in Shakespeare, cinema, and opera. Yet many overlook a crucial aspect of her reign: according to Ptolemaic custom, she was married to both of her brothers. In fact, only six individuals occupied the sixteen slots of her great‑grandparent tree.

While the Ptolemaic dynasty’s obsession with blood‑pure unions contributed to a hereditary predisposition toward obesity, the most dangerous fallout was the ruthless power struggle it ignited. Sibling rivalry transformed into lethal intrigue, with family members routinely murdering one another to secure the throne. Cleopatra herself ordered the deaths of two brother‑husbands and even her sister in her relentless quest for authority.

8 Nahienaena Of Hawaii

In the Hawaiian monarchy, incest was not merely tolerated—it was a privileged right of the royal bloodline. Princess Nahienaena, born in 1815, is a striking example. By her early years she had entered into a romantic liaison with her brother, Prince Kauikeaouli, who would later ascend as Kamehameha III.

When Christian missionaries gained influence, they protested vehemently at the prospect of the siblings marrying and producing an heir. The missionaries succeeded in arranging alternative marriages for both, yet Nahienaena and Kauikeaouli continued their affair clandestinely, defying the new marital arrangements.

Their defiance resulted in scandal: Nahienaena was ostracized by both the church and the increasingly missionary‑shaped populace. A fragile daughter died shortly after birth, and the princess herself succumbed less than a year later. Historians generally agree that the sibling bond went beyond political duty, reflecting a genuine, tragic love.

7 Incan Incest

During the later phases of the Incan Empire, the aristocracy bent the usual prohibition against consanguineous marriage. While commoners were barred from such unions, nobles considered themselves above ordinary law and freely intermarried to reinforce their lineage.

Initially, half‑sisters were paired so that the shared grandfather’s blood would be amplified. However, the practice soon created succession headaches, as rulers often kept multiple wives, mistresses, and concubines. The belief emerged that offspring with two royal parents would boast a stronger claim to the throne.

Emperor Pachacuti attempted to codify the custom by favoring a younger son, Thupa Inka Yupanki, for his military skill, and labeling his sister a “full sister” rather than a half‑sister to bolster the future sons’ rights. The reform proved short‑lived; Thupa’s brother launched a coup, and the dynasty collapsed in civil war a generation later.

6 Maria Of Portugal

Maria I earned the distinction of being Portugal’s first reigning queen, yet she is equally remembered by the moniker “Maria the Mad.” In 1778 she wed her uncle Pedro, later styled Peter III, who was her father’s younger brother and 43 years old, while she was 26.

The family tree grew ever more tangled when their son and heir, Joseph, married his own aunt—Maria’s sister Benedita. Joseph was a mere 15, while Benedita was 30, making Peter III’s daughter‑in‑law, sister‑in‑law, and niece all the same person.

Predictably, the union could not produce children; Benedita suffered two miscarriages, and Joseph died of smallpox two years after his father, accelerating Maria’s mental decline. Her second son assumed the throne, and the royal house was eventually forced to flee to Brazil when Napoleon’s forces invaded. Decades later, Maria II would again marry her father’s brother to resolve a succession crisis.

5 Elisabeth Of Austria

Empress Elisabeth of Austria, often called “Sisi,” was convinced that her lineage bore a curse of madness, though pinpointing the source proved impossible given the tangled web of her ancestry.

Her mother, Ludovika of Bavaria, was one of thirteen children of Prince Maximilian of Bavaria. Ludovika’s sister Sophie married Archduke Franz Karl, giving birth to Emperor Franz Joseph. While Ludovika hoped her daughter Helene would wed the Emperor, Franz Joseph fell instantly for Elisabeth, proposing marriage on the spot.

The marriage proved disastrous. Elisabeth detested court life and clashed constantly with her mother‑in‑law, Archduchess Sophie. Though her health suffered, the cause was not genetic but rather the Emperor’s infidelities and Elisabeth’s own anxieties, obsession with dieting, and eventual nervous breakdown.

The family’s intermarriage continued: Elisabeth’s daughter married her second cousin Leopold, while another of Ludovika’s sisters, Karolina, wed Francis II, making Karolina both aunt and step‑grandmother to the Emperor, as well as sister and step‑mother‑in‑law to Sophie.

4 King Rama V

King Rama V, also known as Chulalongkorn, is celebrated as a reform‑oriented monarch who shielded Siam from colonial domination, abolished slavery, and modernized the nation with public hospitals and railways. Yet his personal life featured a different kind of prolific output.

Adhering to tradition that prized a fertile reign, Chulalongkorn fathered an astonishing 77 children with an estimated 153 consorts, concubines, and wives. The queen’s position was reserved for royal blood, prompting him to select four of his half‑sisters as official spouses.

Despite the sheer number of offspring, the king ensured a Western education for each, sending many sons to study in Europe. He was aware that the world might judge his marital arrangements, but his concern lay with the perception of polygamy rather than incest. Consequently, he only publicly portrayed himself with Queen Saovabha, while the other women were described as “due to custom.”

3 Princess Victoria Melita

Princess Victoria Melita offers a fascinating case study: she married not one but two first cousins. She was also a granddaughter of Queen Victoria through her father, Alfred, Duke of Saxe‑Coburg and Gotha.

Queen Victoria arranged for Victoria Melita to wed her grandson Ernest Louis, Grand Duke of Hesse. The couple produced a daughter and a stillborn son, but the marriage quickly deteriorated when Victoria reportedly caught Ernest in bed with a male servant, leading to volatile confrontations. After Queen Victoria’s death, the pair legally divorced, causing a scandal within aristocratic circles.

Victoria later married her true love, Kirill Vladimirovich, a Russian grand duke and also her first cousin on her mother’s side. Their union, performed without Tsar Nicholas II’s consent, resulted in Kirill’s removal from the navy and a five‑year exile from Russia. Only after a chain of royal deaths elevated Kirill to third in line for succession were they allowed back, yet their relationship remained strained, never fully warming.

2 Queen Victoria

Queen Victoria is renowned as a prolific matriarch who championed the belief that intermarriage among European royalty could secure lasting peace. Her matchmaking, first of her nine children and later of her grandchildren, intertwined nearly every royal house on the continent, but this web of blood also sowed the seeds of imperial decline.

Kaiser Wilhelm II’s deep‑seated insecurities and antagonism toward Britain can be traced to his English mother’s relentless insistence that English culture superseded German, a sentiment that fueled personal vendettas against his cousins King Edward VII and Tsar Nicholas II.

The genetic fallout of Victoria’s close‑kin unions manifested dramatically in the spread of hemophilia. Both Victoria and her husband Albert were first cousins, and their descendants continued to marry within the family, allowing the recessive hemophilia gene to proliferate. Five of Victoria’s grandchildren and one of her children died from complications related to the disease.

Perhaps the most catastrophic outcome was the tragic fate of her granddaughter, Tsarina Alexandra, whose son Alexei suffered from hemophilia. Desperate to heal him, Alexandra placed her trust in the mystic Rasputin, whose influence exacerbated public distrust and contributed to the Russian Revolution. The imperial family was ultimately murdered after Tsar Nicholas II’s abdication.

1 Ancient Rome

The infamous Emperor Nero is remembered for his cruel whims, including rumors of wandering the streets and murdering innocent citizens at random. His mother Agrippina, together with his former tutor Seneca, attempted to curb his excesses, only to provoke even more violent behavior, culminating in Nero’s murder of his own mother.

Agrippina’s ambition was far more intricate than a simple mother‑son power struggle. She married Emperor Claudius—her own uncle—to strengthen Nero’s claim to the throne, a union that Roman law deemed incestuous. She then plotted against Claudius’s natural heir and even arranged the suicide of Claudius’s daughter Octavia’s fiancé.

When Nero married his step‑sister Octavia, the only remaining obstacle was Claudius himself. Agrippina acted again, and a year after the marriage, Claudius died under suspicious circumstances, likely mushroom poisoning. At sixteen, Nero ascended as emperor.

Historical accounts, especially those of Tacitus, reveal that Agrippina’s relationship with Nero went beyond political maneuvering; she was openly affectionate, even sharing kisses, which alarmed contemporaries. Nero’s lover Acte warned him that such incestuous behavior would offend the gods and alienate the army.

Ultimately, Agrippina’s jealousy over Nero’s affairs with women like Acte and Poppaea Sabina—whom she viewed as rivals—led to her downfall. In AD 59, Nero orchestrated his mother’s murder, sealing a grim chapter in Roman imperial history.

Kindree Cushing is a jack‑of‑all‑trades and lover of informative lists.

Incest—sexual relations between close biological relatives—might make most of us squirm, yet it has been a recurring practice across many cultures throughout history. Royal families, in particular, often intermarried to preserve a “pure” bloodline and to safeguard the throne both politically and economically.

Attitudes toward incest have varied wildly; some societies warned of supernatural curses for such unions, while others viewed them as a sacred duty or even a form of worship. The worldwide examples below reveal just how diverse and surprising these customs can be.

10. Fascinating Cases: Historical Incest Overview

10. Ancient Africa

In the bygone Kingdom of Mutapa, located in present‑day Zimbabwe, a monarch boasted over three hundred wives. His “principal” spouses were often his own sisters or even his daughters, and only their offspring were eligible to inherit the throne, keeping the royal line untainted by non‑royal blood.

The practice of royal incest also appeared in the Fon kingdom of Dahomey (now Benin), where the king could take any woman he desired—single, married, foreign, native, free, or enslaved. Female relatives such as cousins were permissible, though full sisters were off‑limits.

9. Ancient Egypt

Pharaonic Egypt held the belief that a royal heiress’s dowry included the very throne itself, and that sibling unions would fortify the bloodline. Numerous 18th‑dynasty pharaohs married sisters or half‑siblings, and the 19th‑dynasty ruler Ramses II certainly followed suit.

Akhenaten, also known as Amenhotep IV, wed his sister Nefertiti, and some scholars suggest his parents were themselves close relatives. Artistic depictions hint at genetic irregularities, later confirmed by DNA analysis of his son Tutankhamun, indicating that long‑standing brother‑sister marriages likely introduced harmful mutations.

8. Roman Egypt

When Rome ruled Egypt, incestuous marriages flourished among non‑royal citizens, even as Roman law frowned upon such unions. Records show ordinary Egyptians marrying brothers to sisters, defying the imperial moral code.

These marriages cut across social strata, with the most astonishing case involving a pair of twins who produced an heir. The phenomenon was especially prevalent among the Greek settler community, where a limited pool of partners may have encouraged such pairings.

7. Zoroastrian Iran

Before the Muslim conquest, Zoroastrian Iran embraced incestuous unions as a sacred act, believing that marriage mirrored divine worship. Texts from the sixth to ninth centuries AD describe mother‑son, brother‑sister, and father‑daughter marriages as spiritually potent.

Such relationships were thought to pave a path to heaven and cleanse the soul of sin. While concrete archaeological evidence of these practices is scarce, religious manuscripts repeatedly reference the theological legitimacy of incest in Zoroastrian doctrine.

6. Europe

From the 15th through the 19th centuries, European royalty frequently married cousins to consolidate power. The Spanish Habsburgs, Prussian Hohenzollerns, French Bourbons, Russian Romanovs, and the British royal family all practiced close‑kin marriage.

Scholars argue that the Habsburg dynasty’s decline was accelerated by inbreeding, which manifested in both mental and physical ailments that weakened the family’s political standing.

5. Madagascar

Anthropologists studying the Malagasy have uncovered a patchwork of incest definitions. In some regions, first‑cousin marriages are accepted, while elsewhere they are strictly forbidden.

Crossing the incest line—whether intentional or accidental—is believed to invite calamities: failed crops, capsizing canoes, child mortality, female infertility, and even birth defects such as horns or humps. These misfortunes are thought to affect the entire community, prompting ritual atonement to restore balance.

4. The Incas

The Inca regarded themselves as descendants of celestial deities, mirroring the myth of the Sun marrying the Moon. Consequently, royal siblings were expected to wed, merging paternal and maternal claims into a single heir.

If a marriage failed to produce offspring, the king would sequentially marry additional sisters, and in the absence of sisters, a first cousin would be selected to preserve the perceived purity of the lineage. Spanish conquest ultimately ended this practice.

3. Polynesia

Among Polynesian elites, a brother‑sister union was thought to endow the child with extraordinary mana—spiritual power and prestige—making the offspring virtually untouchable in succession disputes.

19th‑century Hawaiian scholar David Malo described this “loop, a thing bent on itself,” where chiefs married sisters, half‑sisters, or nieces to keep the bloodline as high‑ranking as possible. The resulting child was deemed divine, ensuring an uncontested claim to leadership.

2. Thailand

Thai monarchs historically maintained extensive harems that often included close relatives. In 1907, King Chulalongkorn (Rama V) married two half‑sisters as queens, seeking an heir of the highest dynastic rank.

Incest was not legally barred for non‑royals, and royal “kingmakers” arranged unions between uncles and nieces or half‑siblings to maximize political legitimacy. The king’s father fathered 84 children with 35 wives, illustrating the scale of intra‑family alliances.

1. Tibet

In Tibetan culture, incest is a taboo rarely spoken of, yet when it occurs, a special pilgrimage to the sacred mountain Chorten Nyima is performed to cleanse the couple’s sins. The Tibetan term “nal” directly translates to “incest.”

Tibetologist Katia Buffetrille recounts a 1989 incident where a village couple, caught in an incestuous act, were beaten and then escorted to Chorten Nyima. After bathing in the holy lake and spring, they received a sealed certificate from a monastery confirming their purification.

Following the ritual, the couple returned to their families and reclaimed their previous social roles. If the male held higher status, his mother would accompany him, while the female’s father would accompany her on the pilgrimage.

Researcher Alexa MacDermot, based in Ireland, notes that the ritual’s completion removes stigma, allowing the pair to reintegrate without lasting shame.