Things you didn't know about the 'Lord of the Rings' author
Kate Middleton might be a commoner, but she is still related to Prince William. They are actually 11th cousins once removed.
All because of Sir William Blakiston, a Baronet whose peerage Kate Middleton didn't inherit.
The couple is related via the High Sheriff of County Durham, Ralph Bowes, a 15th century ancestor of the Queen Mother.
Prince Charles and Lady Diana Spencer were actually seventh cousins once removed.
Queen Elizabeth II and Prince Philip are both related through Queen Victoria. This makes them third cousins.
But they're also both related to King Christian IX of Denmark. Prince Philip had the same great-grandfather as Queen Elizabeth's father. So, this makes them also second cousins once removed.
The House of Habsburg is particularly known for intermarriage. They're famed for a genetic trait known as mandibular prognathism (pronounced jaw) as a result.
Intermarriage in the family led to some really complex and bizarre situations. For instance, Charles II of Spain's mother, Mariana of Austria, was also the niece of his father, Philip IV of Spain.
Maria I of Portugal married her uncle, Pedro, who was her father's brother.
It is believed that Kamehameha (the founder and first ruler of the Kingdom of Hawaii) and his sister Nahi'ena'ena married in secret.
Queen Victoria and Prince Albert had the same grandfather, Francis, Duke of Saxe-Coburg-Saalfeld. This makes them first cousins.
The emperor married his 16-year-old first cousin, famously known as Sisi.
King George IV and Caroline of Brunswick were first cousins. They married in 1795, but separated one year later.
Philip II of Spain and his wife were first cousins once removed.
The Guangxu Emperor, from China, married his first cousin, Xiao Ding Jing.
They both had the same set of grandparents, making them double first cousins.
It is estimated that Chulalongkorn, King of Siam (Thailand) had 153 wives, consorts, and concubines. Among them were his four half-sisters.
King George VI and Elizabeth Bowes-Lyon had a reasonable family distance between them. They were 13th cousins.
King Henry VII married his third cousin, Elizabeth of York.
George V and Mary of Teck shared a great-grandparent, making them second cousins.
Princess Victoria Melita married her first cousin, Grand Duke Ernest of Hesse. She then got divorced and married another cousin, the Grand Duke Kirill Vladimirovich of Russia.
The Earl of Wessex is married to Sophie Rhys-Jones. They are 11th cousins.
The two were brother and sister and became co-rulers of Ancient Egypt.
See also: Iconic women who married into royalty
Following the footsteps of his mother (Queen Victoria), King Edward VII also married his cousin, though he and Alexandra of Denmark were third cousins.
For centuries, marriage had little to do with love, and a lot to do with power. Royals would make arrangements that would serve them both politically and financially, and this often included marrying a relative. While modern royals are now, more often than not, marrying commoners, intermarriage between royals still happens.
Browse though the following gallery and be surprised by the royals who married their relatives.
Royals who married their relatives
Did you know Meghan Markle and Prince Harry are related?
LIFESTYLE Royalty
For centuries, marriage had little to do with love, and a lot to do with power. Royals would make arrangements that would serve them both politically and financially, and this often included marrying a relative. While modern royals are now, more often than not, marrying commoners, intermarriage between royals still happens.
Browse though the following gallery and be surprised by the royals who married their relatives.