Not necessarily. They can be any relation or maybe not related at all. It is a title given by the monarch to whoever they want. Some people have several titles.
Yes
he was hes cousin On the contrary he was the same person
Desdemona's cousin is Lodovico and the duke's messenger is Lodovico as well.
Louis Philippe, Duke of Orleans was chosen as king in the 1830 July Revolution in France. He was the cousin of the ousted King Charles X.
the British King gave it to his cousin the Duke of York, the majority of the people came from england
A King is a more senior position than a Duke.
he was his cousin
Not a king, but a Grand Duke. His name is Grand Duke Henri of Luxembourg
yes king is their cousin he also raps he goes by lil King
no
Most people say that William, duke of Normandy was cruel but he did have at least one friend which was Edward, the Confessor who supposedly had said that William should be the next king. Edward, the Confessor was also a distant cousin of William's and was his best friend.
Yes, she was a half-second cousin to her predecessor Anne Boleyn, as they shared a great-grandmother, Elizabeth Cheney. She was also 5th cousin to the King himself, as she was the great-great-granddaughter of King Edward III through Lionel of Antwerp, 1st Duke of Clarence.