If you are from the broader UK, Commonwealth, or a former colony with any antecedents from the UK, the odds are still good that you are also at least a third cousin of Richard III. The populations of several other European countries are also home to many, many cousins of Richard III, particularly Spain and Portugal, wherein lay the marital destinies of some of his female third cousins. If you are in the west but not of western ancestry, over time, your relatives or descendants will very likely marry a third cousin of Richard III.
How is this possible?
Andrew Millard, a genealogist in Durham, UK, has attempted to calculate "the probability that a present-day English person descends from Edward III." Millard's conclusion is that the probability is well over 99%. As Edward III is the 2nd great-grandfather of Richard III, the odds are you have an ancestral line that runs straight through one of Edward's other great-great-grandchildren, all of whom were third cousins to Richard III.
However, the question remains how many generations removed you are from that point. Benedict Cumberbatch, for instance, is his third cousin, 16 times removed.
You may also have a closer than third cousin relationship to Richard III, as he had nieces and nephews, first and second cousins, with lines surviving to this day. And, he has many lines of cousins that descend from his great-great grandparents other than Edward III (in fact, his maternal line 2nd great grandmother, the mother of Katherine de Roet Swynford, is not even known, so anything is possible).
In fairness, the University of Leicester is claiming only one to 17 million people have connections to Richard III. However, they are not indicating how their probability calculations vary from Millard's (and they may not be familiar with his work). In the days leading up to Richard III's interment, and as his burial site in Leicester becomes a tourist attraction, considering these connections can make history very tangible, universal, and personal.
Richard III's nieces and nephews (who had children)Richard is, infamously, a suspect in the deaths of two of his nephews. However, several of his other nieces and nephews had children with descendant lines surviving to today. Eight of his nieces and nephews, many times removed, were reportedly involved in the legal dispute over whether he would be interred in York or Leicester. His living nieces and nephews descend from the legitimate and illegitimate children of his siblings who are known to have had offspring:
- Anne St. Leger (14 January 1476 – 21 April 1526), who married George Manners, 11th Baron de Ros
- Michael Ibsen is in this line in a completely female descent (which means he carries the mtDNA of Richard), but there are also may who do not follow a single-sex descent line
- Elizabeth of York, queen consort to Henry VII of England (11 February 1466 – 11 February 1503)
- Queen Elizabeth is niece of Richard III, 16 times removed, through this line (Margaret Tudor>Margaret Douglas>Henry Stuart, Lord Darnley>James VI>Elizabeth Stuart, Queen of Bohemia>Sophia, Princess Palatine>George I>George II>Frederick, Prince of Wales>George III>Prince Edward, Duke of Kent and Strathearn>Queen Victoria>Edward VII>George V>George VI>Elizabeth II)
- Cecily of York (20 March 1469 – 24 August 1507), married first John Welles, 1st Viscount Welles and second Thomas Kyme or Keme
- Anne of York (2 November 1475 – 23 November 1511), married Thomas Howard (later 3rd Duke of Norfolk)
- Catherine of York (14 August 1479 – 15 November 1527), married William Courtenay, 1st Earl of Devon
- Elizabeth Plantagenet (born circa 1464), married Thomas Lumley, Esquire, of Beautrove, Durham
- Arthur Plantagenet, 1st Viscount Lisle (1460s/1470s – 3 March 1542), married Elizabeth Grey
- Mary Plantagenet, married Henry Harman of Ellam
- A daughter said to have been the first wife of John Tuchet, 6th Baron Audley
- Margaret Pole, 8th Countess of Salisbury (14 August 1473 – 27 May 1541), married Sir Richard Pole
Richard III's first cousins (survived to adulthood, not known to be childless)
Anyone directly descended from someone on the list below is a first cousin of Richard III (removed as many generations as they are separated from the person below).
- William Bourchier, Viscount Bourchier (d. 1480), married Anne Woodville
- Sir Henry Bourchier (d. 1462), married Elizabeth Scales, 8th Baroness Scales.
- Humphrey Bourchier, 1st Baron Cromwell (d. 14 April 1471), slain at the Battle of Barnet.
- John Bourchier, 6th Baron Ferrers of Groby (d.1495), married firstly Elizabeth Ferrers, and secondly Elizabeth Chichelle
- Sir Thomas Bourchier (b. prior to 1448 d. 1492), married Isabella Barre
- Edward Bourchier (d. 30 December 1460), slain at the Battle of Wakefield (offspring?)
- see also Sir Thomas Grey below
- Ralph Neville, 2nd Earl of Westmorland, married Elizabeth Percy, married Margaret Cobham
- John Neville, Baron Neville, married Anne Holland
- Sir Thomas Neville, married Elizabeth Beaumont
- Margaret Neville, married Sir William Lucy
- Havisia Neville, married Sir William Bradford Heslerton
- Joan Neville, married Walter Hart Griffith
- John Neville, married Lucy Somerset, married Margaret Plumpton, married Elizabeth Newmarch
- Sir Thomas Grey (1404 – d. before 1426), married Isabel of Cambridge (Richard III's paternal aunt) and some sources indicate they had a son before the marriage was annulled - line most likely died out at this point
- Sir Ralph Grey (d. 17 March 1442), married Elizabeth FitzHugh
- Eleanor Grey, married Sir John Arundel
- Joan Grey, married Sir John Salvin
- Elizabeth Grey, married firstly, Sir William Whitchester, and secondly, Sir Roger Widdrington
- Margaret Grey, married Gerard Widdrington
- Sir Gilbert Lancaster
- Sir Thomas Dacre (d. before 5 January 1458), married Elizabeth Bowet
- Humphrey Dacre, 1st Baron Dacre of Gilsland (d. 30 May 1485), married Mabel Parr
- Joan Dacre, married Thomas Clifford, 8th Baron de Clifford
- Margaret Dacre, married John le Scrope
- Henry Scrope, Baron Scrope of Bolton, married Elizabeth Scrope
- Isabella Scrope, married Richard Plumpton
- Margaret Scrope, married Thomas Grey, Baron Richemond
- Alexander Cressener of Alphamstone (b. c. 1422 - d. 18 Jun 1498), married Alicia Radcliffe
- Cecily Neville (1424–1450), married Henry de Beauchamp, 1st Duke of Warwick, line subsequently died out
- Richard Neville, 16th Earl of Warwick (1428–1471), married Lady Anne Beauchamp
- Alice Neville (c.1430–1503), married Henry FitzHugh, 5th Baron FitzHugh
- John Neville, 1st Marquess of Montagu (?1431–1471), married Isabel Ingaldesthorpe
- Joan Neville (1434–1462), married William FitzAlan, 16th Earl of Arundel
- Katherine Neville (1442–1503), married first William Bonville, 6th Baron Harington, and second William Hastings, 1st Baron Hastings
- Eleanor Neville (1447–1482), married Thomas Stanley, 1st Earl of Derby
- Lady Alice Neville, married Sir John Conyers
- Lady Elizabeth Neville, married Sir Richard Strangeways
- Lady Joan Neville, married Sir Edward Bedhowing
- Sir Henry Neville (d. 26 July 1469), married Joan Bourchier
- Thomas Neville, of Shenstone, Staffordshire ?
- Jane Neville, some sources report she married Oliver Dudley
- Richard Nevill (1439 – bef. 1476) ?
- Sir George Nevill (c.1440–1492), married Margaret Fenne (ancestors to George Washington), married Elizabeth
- Alice Nevill, married Sir Thomas Grey
- Catherine Nevill (b.c. 1444), married John Iwardby
- Catherine Nevill (b. c. 1452/bef. 1473) married Robert Tanfield (b. 1461) (ancestor of Thomas Jefferson)
- Margaret Nevill (b.bef. 1476-1506), married John Brooke, 7th Baron Cobham
- John de Mowbray, 3rd Duke of Norfolk (1415–1461), married Eleanor Bourchier
- Joan Strangeways, married Sir William Willoughby (they were ancestors of Herbert Hoover, among many others)
- Katherine Strangeways, married Henry Grey, 4th (7th) Baron Grey of Codnor
- Henry Percy, 3rd Earl of Northumberland (25 July 1421 - 29 March 1461, Battle of Towton), married Eleanor Poynings
- Thomas Percy, 1st Baron Egremont (29 November 1422, Leconfield, Yorkshire - 10 July 1460, Battle of Northampton, England), married Eleanor Percy
- Lady Katherine Percy (28 May 1423 - d. aft 1475), married Edmund Grey, 1st Earl of Kent
- Sir Ralph Percy (1425 - 25 April 1464, Battle of Hedgeley Moor), married Eleanor Acton, married Jane Teye
- Sir Richard Percy (1426/7–29 March 1461, Battle of Towton), married Catherine Percy, of Thornton-Bridge
- Humphrey Stafford, Earl of Stafford (d. 1458), married Margaret Beaufort, Countess of Stafford
- Catherine Stafford (1437 – 26 December 1476), married John Talbot, 3rd Earl of Shrewsbury
- John Stafford, 1st Earl of Wiltshire (d. 8 May 1473), married Constance Green
- Joan Stafford (1442–1484), married first William Beaumont and secondly William Knyvett
- Anne Stafford (1446–1472), married first Aubrey de Vere, son of John de Vere, 12th Earl of Oxford, married secondly Thomas Cobham, 5th Baron Cobham
- Margaret Stafford, married Robert Dunham
Richard III's second cousins
Richard III's third cousins