Queen Elizabeth (the daughter of King George VI) and King Harald of Norway (the son of Crown Prince Olav) are second cousins.
His direct descendants became the British royal family after the Norman invasion of Britain in 1066, when Rollo's great-great-great-grandson, William the Conqueror (William I of England), successfully conquered England. William the Conqueror's direct descendants include current Queen Elizabeth II.
Chroniclers of Germanic peoples traced the ancestry of their kings back to the god Wōden (Odin). If such descents were true, Queen Elizabeth II would be a descendant of Woden, via the kings of Wessex.
Because so many monarchs descend from both Queen Victoria and King Christian IX of Denmark, the relationship between these two monarchs is of some interest. These monarchs were third cousins through their mutual descent from King George II of Great Britain.
Fortunately, in modern times, the relationship has been somewhat more peaceful than it was 1000 years ago. King Harald and Queen Elizabeth are second cousins. King Edward VII and Queen Alexandra of the United Kingdom are the great-grandparents of both the Norwegian and British monarchs.
In modern times, among European royalty at least, marriages between royal dynasties have become much rarer than they once were. This happens to avoid inbreeding, since many royal families share common ancestors, and therefore share much of the genetic pool.
The British royal family is descended from Edward VII's son, George V and the Norwegian royal family is descended from Edward VII's daughter Maud who married King Haakon VII. Thus King Harald V and Queen Elizabeth II are second cousins. King Harald is the foreign royal most closely related to Queen Elizabeth.
At the other end of the scale is Charles II, King of Spain from 1665 to 1700, who was determined to be the 'individual with the highest coefficient of inbreeding', or the most inbred monarch.
The Danish monarchy is one of the oldest in the world. Queen Margrethe II's heritage can be traced back more than a thousand years to a king believed to be born around year 900.
Is the Swedish royal family related to the British royal family? Yes! The Swedish and British royal families are connected through Queen Victoria, who is the great great-grandmother of both Queen Elizabeth II and King Carl XVI Gustav.
The longest family tree in the world is that of the Chinese philosopher and educator Confucius (551–479 BC), who is descended from King Tang (1675–1646 BC). The tree spans more than 80 generations from him and includes more than 2 million members.
In all, the descent from Cerdic to Elizabeth II encompasses fifty-one generations, making the line one of the longest recorded in the world. The reason that the line of descent follows the monarchs of Scotland is that the male line is always followed first.
Elizabeth was born to Prince Albert and Lady Elizabeth Bowes-Lyon and had a younger sister, Princess Margaret. She is also a descendant of Queen Victoria. Elizabeth married her distant cousin Philip Mountbatten and had four children: Prince Charles (heir apparent), Princess Anne, Prince Andrew, and Prince Edward.
1. Saudi Arabia's royal family: $1.4 trillion (£1.1tn) The wealthiest royal family in the world is the House of Saud, which is estimated to be worth more than a jaw-dropping $1.4 trillion (£1.1tn). This unimaginable wealth is spread out among the vast family's 15,000 or so members.
The current reigning monarch, Queen Elizabeth II, can trace her ancestral history all the way back to the 9th Century, some 1,200 years. In these 1,200 years, there have been some weird and wonderful members of the Royal Family, each with a more interesting story than the next.
Still, despite a couple centuries of toppling kings, there are 44 monarchies in the world today.
Members of the Middleton family have been related to the British royal family by marriage since the wedding of Catherine Middleton and Prince William in April 2011, when she became the Duchess of Cambridge.
Data on inbreeding in several contemporary human populations are compared, showing the highest local rates of inbreeding to be in Brazil, Japan, India, and Israel.
Upon becoming independent in 1905, Norway decided through a referendum to remain as a monarchy, with its first monarch being the Danish-born King Haakon VII, whose family consisted of the British Princess Maud and their son Olav. It is King Haakon's descendants that today make up the current royal family of Norway.
King Harald V of Norway
The non-British royal most closely related to Queen Elizabeth, Harald V is also a great-great-grandchild of Queen Victoria and is actually descended from the same branch of the family as Elizabeth II.
Having had the same great-great-grandmother (Queen Victoria), Elizabeth (the progeny of Victoria's son, King Edward VII) and Philip (the progeny of Victoria's daughter, Princess Alice) are third cousins.
On June 19, 1917, during the third year of World War I, Britain's King George V orders the British royal family to dispense with the use of German titles and surnames, changing the surname of his own family, the decidedly Germanic Saxe-Coburg-Gotha, to Windsor.
They both had some of the same royal blood, separated by generations. Prince Philip, who died on Friday at the age of 99, was not only related to Queen Elizabeth the II by marriage. They were also related by blood. Elizabeth and Philip were great-great grandchildren of Queen Victoria.
Royals have been marrying their cousins since time immemorial, traditionally as a means of strengthening political alliances. What might be surprising though is that members of the royal family have continued to marry their cousins, right up to the present day!