I don't think most of us would realise that all of Henry VIII’s wives had one thing in common: they were all descended from Edward I. Some were by his first wife Eleanor of Castile and some were by his second, Marguerite of France and in some cases both. In Hampton Court Palace in King Henry VIII’s apartment there are six stained glassed windows showing his wives pedigrees from King Edward I, with prominent ancestry featured.
In fact, Henry was closely related to two of his wives: Katherine of Aragon and his last wife, Kateryn Parr (or Katherine Parr as some call her, depending on who is doing the writing.) All three share a common ancestry with John of Gaunt 1st Duke of Lancaster as so many did. It seems that John of Gaunt got around and liked the ladies.
So it seems that Katherine of Aragon was Henry's 3rd cousins once removed and 4th cousin by John of Gaunt's first two wives. This lineage made her very appealing to Henry's father, Henry VII when he was choosing a bride for his eldest son Arthur. This lineage also gave their daughter Princess Mary a strong grip of the throne through both her mother and father. Her claim to the throne was undeniable yet Henry threw away her chances and declared her illegitimate when he moved on to wife number 2, Anne Boleyn. It is also worth mentioning here that both Anne Boleyn and Henry's fourth wife Catherine Howard were also first cousins. Anne's mother and Catherine's father were brother and sister. The girls had nothing else in common however. Catherine was fifteen years younger than Anne and her side of the family was relatively poor while Anne considered her cousin's side of the family quite vulgar. Strange though how both girls were the only ones who ended up on the scaffold for much the same crime - adultery.
Kateryn Parr however had multiple links to Henry through both her mother and father. Kateryn and Henry were 3rd cousins through Lady Maud Parr through Sir Richard Wydeville and Joan Bedlisgate - grandparents of Elizabeth Woodville, wife of Edward IV; 3rd cousins once removed through Ralph Neville, 1st Earl of Westmorland and Lady Joan Beaufort - parents of Lady Cecily, Duchess of York and mother of both Edward IV and Richard III; 4th cousins through John of Gaunt and Katherine Swynford - grandparents of John Beaufort 1st Duke of Somerset; 4th cousins once removed and 5th cousins through Sir Thomas Holland, 2nd Earl of Kent.