On 11 Jul 1372 [his father] Edmund of Langley 1st Duke York (age 31) and [his mother] Isabella of Castile Duchess York (age 17) were married at Wallingford, Oxfordshire [Map]. She by marriage Countess Cambridge. She being the younger sister of [his aunt] Constance (age 18) who had married Edmund's older brother [his uncle] John of Gaunt 1st Duke Lancaster (age 32) a year before. An example of Marriage of Two Sets of Siblings. She the illegitmate daughter of Peter "Cruel" I King Castile and Maria Padilla. He the son of King Edward III of England (age 59) and Philippa of Hainault Queen Consort England.

On 04 Nov 1393 [his father] Edmund of Langley 1st Duke York (age 52) and [his step-mother] Joan Holland Duchess York (age 13) were married. She by marriage Duchess York. The difference in their ages was 38 years. She the daughter of Thomas Holland 2nd Earl Kent (age 43) and Alice Fitzalan Countess Kent (age 43). He the son of King Edward III of England and Philippa of Hainault Queen Consort England. They were half second cousin once removed. She a great x 2 granddaughter of King Edward "Longshanks" I of England.

Around 1404 [his future brother-in-law] John Clifford 7th Baron Clifford (age 15) and Elizabeth Percy Countess of Westmoreland (age 9) were married. She by marriage Baroness de Clifford. They were third cousin once removed. He a great x 4 grandson of King Edward "Longshanks" I of England. She a great x 2 granddaughter of King Edward III of England.

In May 1406 Richard of Conisbrough 1st Earl Cambridge (age 20) and Anne Mortimer (age 15) were married. The marriage apparently took place in secret possibly because she was a descendant of King Edward III of England although she wasn't at the time Heir to the Throne of England although their issue would become so. She died five years later. She the daughter of Roger Mortimer 4th Earl March 6th Earl Ulster and Eleanor Holland Countess March and Ulster. He the son of Edmund of Langley 1st Duke York and Isabella of Castile Duchess York. They were first cousin twice removed. He a grandson of King Edward III of England. She a great x 2 granddaughter of King Edward III of England.

Before 24 Jul 1406 John Neville 6th Baron Latimer of Corby (age 24) and [his future wife] Maud Clifford Countess Cambridge (age 17) were married. She by marriage Baroness Latimer of Corby. They were second cousin twice removed. He a great x 5 grandson of King Henry "Curtmantle" II of England. She a great x 4 granddaughter of King Edward "Longshanks" I of England.

After 21 Sep 1411 Richard of Conisbrough 1st Earl Cambridge (age 26) and Maud Clifford Countess Cambridge (age 22) were married. He the son of Edmund of Langley 1st Duke York and Isabella of Castile Duchess York. He a grandson of King Edward III of England. She a great x 4 granddaughter of King Edward "Longshanks" I of England.

On 18 Feb 1413 [his son-in-law] Thomas Grey of Heton (age 9) and [his daughter] Isabel York Countess Eu and Essex (age 4) were married. She the daughter of Richard of Conisbrough 1st Earl Cambridge (age 27) and Anne Mortimer. They were fourth cousins. He a great x 4 grandson of King Edward "Longshanks" I of England. She a great granddaughter of King Edward III of England.

Before 1414 John Neville 6th Baron Latimer of Corby (age 32) and [his wife] Maud Clifford Countess Cambridge (age 24) were divorced.