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!
Queen Victoria and Prince Albert: 1st cousins
Queen Victoria and Prince Albert were first cousins, having shared the same grandfather, Francis, Duke of Saxe-Coburg-Saalfeld:
Victoria: Victoria was the daughter of Francis’s daughter, Princess Victoria of Saxe Coburg-Saalfeld.
Albert: Albert was the son of Francis’s son, Ernest III, Duke of Saxe-Coburg-Saalfeld.
Fun fact: The match between Victoria and Albert was encouraged, if not made, by their mutual Uncle Leopold, the second son and third child of Francis. More about Uncle Leopold later.
King George IV and Caroline of Brunswick: 1st cousins
Just one generation prior, Queen Victoria’s uncle, King George IV, married his first cousin Caroline:
George IV: George IV was the son of King George III, who was the younger brother of Princess Augusta Frederica.
Caroline: Caroline was the daughter of Princess Augusta Frederica.
Sharing a grandfather, King George III, George IV and Caroline were first cousins. However, unlike Victoria and Albert, George IV and Caroline did not have a fruitful or a happy marriage. In fact, they married in 1795 and had permanently separated for good by 1796.
The unhappy marriage between cousins that changed history
King George IV and Caroline’s unhappy union produced only one child, Princess Charlotte, who died in childbirth in 1817. When George IV died, the crown went to the next oldest son of King George III, William IV (who was King George IV’s brother), who was 64 years old at the time. When King William IV died without legitimate children, the crown went to Victoria, the oldest living legitimate grandchild of King George III (her father was King George III’s son, the late Edward, Duke of Kent and Strathearn).
Had the marriage between King George IV and Caroline lasted longer, there might have been a living heir when King George IV died, and Queen Victoria would never have been Queen. In this photo, Princess Charlotte is shown with her husband, Leopold of Saxe-Coburg, who was the brother of Queen Victoria and Prince Albert’s parents, and who made the match between Victoria and Albert.
King Edward VII and Queen Alexandra: 3rd cousins
Like his mother, Queen Victoria, King Edward VII also married his cousin, albeit a more distant one. In 1863, Edward VII, who was then known as Prince Albert Edward, married Alexandra of Denmark:
Edward VII: Edward, born Albert Edward, was the son of Queen Victoria, who was the great-granddaughter of King George III, who was the son of King George II. Accordingly, King Edward VII was a great-great-grandson of King George II.
Alexandra: Queen Alexandra, born Alexandra of Denmark, was a great-great-granddaughter of King George II (her great-grandmother, Princess Mary, was George II’s daughter).
Sharing great-great grandparents made Edward VII and Alexandra 3rd cousins.
King George V and Queen Mary: 2nd cousins
Like his father, King Edward VII, and his grandmother, Queen Victoria, King George V married his cousin, in this case, his second cousin, Mary of Teck.
George V: George, being the son of King Edward VII, was the great-grandson of King George III.
Mary: Queen Mary, born Mary of Teck, was a great-granddaughter of King George III (her mother, Princess Mary Adelaide of Cambridge, was George III’s granddaughter; her father was one of George III’s youngest sons, Prince Adolphus of Cambridge).
Sharing a great-grandparent made George V and Mary second cousins.
Queen Elizabeth II and Prince Philip (Part I): 3rd cousins
Both Queen Elizabeth II and her husband, Prince Philip, can call Queen Victoria, “Great-Great-Grandmum,” which makes them third cousins.
Elizabeth II: Elizabeth is the great-granddaughter of King Edward VII, Queen Victoria’s son.
Philip: Philip’s great-grandmother was Princess Alice, Queen Victoria’s daughter.
Queen Elizabeth II and Prince Philip (Part II): 2nd cousins once removed
Queen Elizabeth II and Prince Philip are not only related through Queen Victoria but through King Christian IX of Denmark.
Elizabeth II: King Christian IX of Denmark was the father of Alexandra of Denmark, who married King Edward VII, Queen Victoria’s son. As discussed above, King Edward VII and Alexandra were Queen Elizabeth’s great-grandparents. Therefore, King Christian IX of Denmark was Queen Elizabeth II’s great-great-grandfather.
Philip: King Christian IX of Denmark was the father of Prince George I of Greece, who was the father of Prince Andrew of Greece and Denmark, who was Prince Philip’s father. King Christian IX of Denmark was, therefore, Prince Philip’s great-grandfather.
To put it another way, Prince Philip had the same great-grandfather as Queen Elizabeth’s father, making Philip and Elizabeth second cousins once removed.
King George VI and Elizabeth Bowes-Lyon: 13th cousins
Queen Elizabeth II’s parents were King George VI and Elizabeth Bowes-Lyon (who as King George VI’s wife became Queen Elizabeth, The Queen Mother), both of whom are descendants of Henry Tudor, who became King Henry VII. King Henry VII was the 12th great-grandfather of both King George VI and Elizabeth Bowes-Lyon, but whereas George descended from Henry’s daughter, Mary, Elizabeth descended from Henry’s daughter, Margaret.
Henry VII and Elizabeth of York: 3rd cousins
The relative from whom both King George VI and Elizabeth Bowes-Lyon descended, King Henry VII, himself married his cousin Elizabeth of York, who shared a great-great-grandparent, John of Gaunt, Duke of Lancaster, which makes them third cousins (Elizabeth of York descended from John of Gaunt’s daughter, Joan Beaufort, and King Henry VII descended from John of Gaunt’s son, John Beaufort).
Charles and Diana: 7th cousins, 1x removed
Prince Charles and his first wife, born Lady Diana Spencer who eventually was styled as Diana Princess of Wales, were seventh cousins once removed via William Cavendish, 3rd Duke of Devonshire.
The Duke and Duchess of Cambridge: 11th cousins 1x removed
Although Catherine Middleton is considered a commoner (in that she isn’t a peer of the Queen based Britain’s peerage system), she is actually related to her husband, Prince William, albeit distantly. They are 11th cousins once removed, via Sir William Blakiston, a Baronet (whose peerage Catherine was not eligible to inherit).