Prince Philip and Queen Elizabeth II
Queen Elizabeth II and Prince Philip are secretly related. Pictured: Prince Philip and Queen Elizabeth II wave to the crowd from the balcony of the city hall 'Roemer' on June 25, 2015 in Frankfurt am Main, Germany. Getty Images/Thomas Lohnes

Queen Elizabeth II and Prince Philip are related.

The Queen and the Duke of Edinburgh have been married for 71 years now. However, according to Reader's Digest, their relationship goes much further back. The two have known each other since childhood as they are cousins.

The publication noted that the Queen and the duke are not just cousins, they are cousins through more than one line of descent. Prince Philip and Queen Elizabeth II are both great-great-grandchildren of Queen Victoria.

The monarch was the eldest child of King George VI, the second son of King George V, who was the second son of King Edward VII, Queen Victoria's second child.

On the other hand, Prince Philip was the son of Princess Alice of Battenberg, daughter of Princess Victoria of Hesse, whose mother was Princess Alice, Queen Victoria's third child.

The Queen and Prince Philip are also related through King Christian IX. King Christian IX of Denmark is Her Majesty's great-great-grandfather and Prince Philip's great-grandfather.

Although the two are related, their marriage was not arranged by their families. When Queen Elizabeth II was just 13 years old, she was smitten when she met 18-year-old Prince Philip, a navy cadet and Greek prince, during a tour of the Royal Navy College.

According to Marion "Crawfie" Crawford, the then-princess reportedly "never took her eyes off" Prince Philip. However, at that time, he "did not pay her any special attention." It was only several years later that their friendship turned romantic.

In one letter, Queen Elizabeth II reportedly gushed about her "absolute angel" prince. "We behave as though we had belonged to each other for years," she wrote.

Prince Philip also gushed about the Queen. "To have been spared in the war and seen victory, to have been given the chance to rest and to re-adjust myself, to have fallen in love completely and unreservedly, makes all one's personal and even the world's troubles seem small and petty," the duke said.

Although the two were very much in love, King George VI delayed their wedding and told Prince Philip to wait until his daughter was 21. The king was reportedly furious when he learned that Prince Philip proposed to Queen Elizabeth II without informing him.