A tradição de se casar dentro da família na realeza europeia

O príncipe Charles e Camilla são provavelmente primos de segundo grau. A bisavó de Camilla, Alice Keppel, era amante de Eduardo VII da Inglaterra e, juntos, tiveram uma filha, Sonia. Camilla, a atual esposa do príncipe Charles, é neta de Sonia. Charles e Camilla são primos de segundo grau uma vez removidos, então eles são o produto de um casamento de primos de segundo grau.

A família real da Espanha é um bom exemplo de endogamia. Os pais do atual rei, Juan Carlos e Sophia da Grécia, têm problemas com endogamia. Do lado de Juan Carlos, vemos os resquícios da hemofilia transmitidos devido ao casamento misto narrado pela Rainha Vitória. Os tios de Juan Carlos, Alfonso e Gonzalo, morreram por falta de coagulação do sangue que se acredita ter sido causada por sua leve consanguinidade.

A mãe do rei, Sophia, sem dúvida tem um dos piores casos de endogamia moderna. Dois de seus bisavós eram irmão e irmã, e o que é ainda pior é o fato de que seus bisavós também são seus tataravós porque a família real alemã se casou entre si.

O príncipe Philip, marido da falecida rainha Elizabeth, também é um produto da consanguinidade real. O príncipe Philip, como a rainha, é o infeliz produto do casamento misto que envolveu os casamentos reais europeus no século 19.

Para se aprofundar nos detalhes, os bisavós maternos do príncipe Philip eram a rainha Vitória do Reino Unido e o príncipe Albert de Saxe-Coburgo-Gota. Eles eram primos de primeiro grau, compartilhando o mesmo conjunto de avós. Essa estreita relação familiar destaca a prática de casamentos mistos na era vitoriana e seu impacto nas gerações subsequentes.

Additionally, both of Prince Philip's great-grandfathers played roles in perpetuating the pattern of inbreeding. His maternal great-grandfather, King Christian IX of Denmark, was a prominent figure in European royal circles. King Christian's daughter, Princess Alexandra of Denmark, married Queen Victoria's son, Edward VII, further consolidating the interconnections between royal families.

Prince Philip's other great-grandfather was Grand Duke Louis IV of Hesse and by Rhine. He married Queen Victoria's second daughter, Princess Alice, making them Prince Philip's maternal great-grandparents. What makes this connection particularly notable is that Grand Duke Louis IV was the uncle of Prince Philip's paternal great-grandfather, Grand Duke Ludwig III of Hesse and by Rhine. The marriage of Prince Philip's great-grandparents, Princess Alice and Grand Duke Louis IV, effectively made their children both first cousins and second cousins.

O rei e a rainha da Grécia, Constantino II e Ana Maria da Dinamarca, são primos duas vezes, assim como a rainha Elizabeth II e o príncipe Philip. Ambos são descendentes da Rainha Vitória e do Rei Christian, o 9º da Dinamarca. No entanto, ao contrário da Rainha e do Príncipe da Inglaterra, o Rei e a Rainha da Grécia são triplamente relacionados. Eles compartilham exatamente o mesmo coeficiente de consanguinidade, o que significa exatamente a mesma quantidade de endogamia.

Empress Napoleon, also known as Mary Louise of Austria, was part of an incredibly inbred family. When Napoleon struggled to provide an heir with his first wife, Josephine, he forced Josephine's daughter to marry his brother. This meant that his stepson was also his brother. However, the most inbred member of the Napoleonic family was Napoleon's second wife, Empress Napoleon. Born as Maria Ludovica Leopoldina Franziska Therese Josepha Lucia, Mary Louise hailed from the House of Habsburg, a family known for its extensive history of intermarriage and consanguinity. In the case of Mary Louise, her parents were double first cousins, intensifying the level of shared ancestry within her immediate family.

Alfonso, the Prince of Spain, was the heir to the Spanish throne in the 1920s, during a highly unstable time in Spanish politics. Like Edward VIII of England, Alfonso renounced his rights to the Spanish throne to marry a commoner. Unfortunately, he passed away in 1938 due to a car accident. His hemophilia, a condition that prevents blood clotting, caused him to bleed to death. Inbreeding within the Spanish royal family played a role in the occurrence of recessive genes inherited by Alfonso. As the great-grandchild of Queen Victoria, who carried hemophilia in her family, Alfonso faced increased risk. The Spanish royal family has a history of marrying close relatives, as mentioned before. Ultimately, Alfonso suffered due to the inbreeding of his ancestors and Queen Victoria's ambition to solidify her reputation as the grandmother of Europe.

Archduchess Gizella of Austria, daughter of Emperor Franz Joseph and Empress Elizabeth, is a lesser-known figure in history. She was the neglected daughter of her parents, who were first cousins. The intense strain caused by their inbreeding affected their children's health. For example, their eldest daughter Sophie died in infancy, likely due to the effects of inbreeding. Another child, Rudolf, suffered from genetic abnormalities and chronic depression, eventually taking his own life. Recent studies have shown a common occurrence of depression within the Habsburg dynasty, suggesting a genetic link. Gizella herself became a figurehead for the consequences of Habsburg inbreeding. She was forced to marry her own cousin at the request of her mother, resulting in physical and emotional suffering for her children. Among her four children, all of them shared eight great-grandparents, who, unfortunately, were not genetically diverse. This situation further compounded the issues caused by inbreeding.

Ludwig II, the Mad King of Bavaria, was a beloved cousin of Empress Elizabeth of Austria. He had a strong appreciation for the arts and commissioned the magnificent Neuschwanstein Castle in the 1800s. However, Ludwig suffered from intense feelings of depression, and his inbreeding is believed to be a significant contributing factor to his mental health struggles. Despite his artistic achievements, Ludwig was eventually dethroned, with his counselors claiming he was insane. Modern studies suggest that Ludwig's depression stemmed from intense guilt over his homosexuality. Nevertheless, inbreeding likely played a role in the intensity of his depression. Interestingly, Ludwig's successor was even more mentally unstable than he was.

A rainha Liliuokalani do Havaí, a última monarca reinante do Havaí, também tinha um alto grau de endogamia em sua ancestralidade. É importante notar que existe um estereótipo infeliz sobre o Havaí ter endogamia desenfreada, o que não era necessariamente verdade no período moderno. No entanto, a família de Liliuokalani tinha relações de sangue próximas. Seu avô, o Alto Chefe Kamehameha, foi seu bisavô duas vezes porque seus dois avôs eram irmãos.

King Harald V of Norway holds the distinction of being one of the most inbred royals currently alive. His parents were first cousins, which significantly limited the number of unique great-grandparents he had. While most people have eight unique great-grandparents, Harald only has six. His grandmother and grandfather were not only siblings but also first cousins to each other. Further back in his ancestry, his great-grandmother, who appears twice, was the niece of his great-grandfather. This extensive inbreeding within Harald's lineage makes him the most inbred royal of the present time.