If you wonder if any historical discoveries or speculations about the legitimate or otherwise birth of medieval persons can affect the claim to the throne of the present British monarch, the answer is no. Her claim to the throne begins with the events of 1688, and no prior historical events can make it stronger or weaker. If the world began in about the year 1550 it would not change her claim.
After the childless King William III and Queen Mary II usurped the thrones of England, Scotland, Ireland and France in 1688-89, the English Parliament passed several laws restricting the future succession to the throne to the nearest Protestant descendant of the Stuart Dynasty. They included the Bill of Rights of 1689 and the Act of Settlement of 1701. When England and Scotland united to form Great Britain in 1707 the Protestant succession was reaffirmed. Thus in 1714 George, Elector of Hanover, became King George I of Great Britain, Ireland and France. In 1801 Great Britain and Ireland united to become the United Kingdom.
Since 1714 every monarch of Great Britain or the United Kingdom has been the legal and rightful successor of George I, who was the nearest Protestant heir to the Stuart Dynasty as mandated by the Bill of Rights, the Act of Settlement, and other laws.
Unless, of course, some rumored royal secret goings on were correct. King George IV, for example, was a bigamist, and it is unclear which, if either, of his marriages was legally valid. And Mrs. Fitzherbert, his secret wife, never answered the question of if she had any children with George IV.
Queen Victoria, the niece of George IV, was rumored to worry about someone claiming the throne as a secret child of George IV.
James Ord, father of US general Edward Otho Cresap Ord, was rumored to be the son of George IV and Maria Fitzherbet.
But until and unless some proof of any such skullduggery and hanky panky turns up, we have to accept that the British throne has passed from rightful heir to rightful heir for three hundred twenty nine years since 1688. This compares to 340 years of legal succession in Denmark from 1523 to 1863. Thus the present monarch, Queen Elizabeth II, is the rightful heir of all previous monarchs back to the invading and usurping pair William III and Mary II. And only that far back, unless one totally accepts the ideology used to justify their invasion and usurpation.
If someone does not totally accept the ideology used to justify the invasion and usurpation of William III and Mary II, then one will tend to believe that Duke Franz of Bavaria is the rightful heir by genealogy of the Stuart, Tudor, Plantagenet, Norman, and Bruce Dynasties that ruled England from 1066 to 1688 and Scotland from 1306 to 1688.
Though alternate claims could be made to be the rightful heirs of some of those English or Scottish monarchs.
And that the heirs of John I Balliol are by genealogy the rightful heirs of King Malcolm III of Scotland and his successors until 1290, and also the rightful heirs of the Anglo-Saxon kings of England of the House of Wessex.
(see posts numbers 5, 25, 27, & 28)
And that Karl von Habsburg is probably the rightful heir by genealogy of King Harold II Godwinsson.
There is a complication here. Emperor Franz Joseph I (1830-1916) was probably the heir of Harold II Godwinsson. But Emperor Franz Joseph I (1830-1916) has three possible heirs.
By the rule of male preference primogeniture, the rule that passed the heirship of Harold II down to Franz Joseph, his heir is Guillaume, Prince of Windisch-Graetz (b. 1950).
By the rule of male only primogeniture, or agnatic primogeniture, the heir of Franz Joseph is George, 3rd Duke of Hohenberg (b. 1929).
But George's grandparents, Archduke Franz Ferdinand and Sophie Duchess of Hohenberg, had a nondynastic, unequal, or morganic type of marriage, making their descendants unable to inherit the Austrian throne. That makes the right to the Austrian throne pass to Karl von Habsburg, the third potential heir of King Harold II Godwinsson.
Some historians have claimed that King Harold II Godwinsson was descended from King Aethelred, the older brother of King Alfred the Great, which would make the heirs of Harold II the rightful heirs of Anglo-Saxon England, if true.
And Mr. Evan Vaughan Anwyl of Tywyn (born 1943) may be the rightful heir of the kings of Gywnedd and Kings of the Britons.
Anyway, it doesn't matter to the present Queen Elizabeth II whether any royals reigning before 1688 were of legitimate or illegitimate birth. Her claim to the throne begins with the events of 1688.
As another example, in 977 King Lothair of France's wife Queen Emma was accused of adultery with Bishop Adelberen of Laon by Lothair's brother Charles. Nobody knows if the charges were true. Emma and Adelberen were not convicted and Charles was exiled from France. If the charges were false Lothair and Emma's son Louis was the rightful heir to the throne, if the charges were correct Charles would be the rightful heir to the throne.
In 978 Lothair invaded the Holy Roman Empire and Emperor Otto II retaliated by invading France and proclaiming Charles the new king. And no matter who was the rightful king or heir of France before, the instant that the emperor decreed that Charles was the king of France, all right to the throne was snatched away from Lothair and his descendants and/or successors - such as the Capetians and Bourbons - and granted to Charles and his heirs forever, or until such time as some future emperor should decree otherwise.
So it doesn't matter if Emmas's son, the future Louis V, was really Lothair's legitimate son or the bastard son of Bishop Adelberen of Laon. When the emperor decreed that Charles was the king of France, Louis and all his successors lost all right to become king.
Centuries later four future successors of Lothair and Louis married two sets of sisters, two daughters of the Count of Burgundy and two daughters of the Duke of Burgundy, just to confuse everyone.
The future Louis X, Philip V, and Charles IV, sons of Philip IV the (un) Fair, and their first cousin the future Philip VI, were married to those four young women when three of the wives were accused of adultery in the Tour de Nesle affair in 1314.
Posts # 1, 14, here: http://historum.com/medieval-byzantine-history/121828-navarre-succession-crises-1316-1322-1328-a-2.html
discuss the possible lines of succession to the potential heirs.
And none of these possible cases of royal illegitimacy matter to the present day presidents of France whose right depends only on being elected according to the terms of the constitution of the Fifth Republic of France established in 1958.
And for much the same reasons the claim of Elizabeth II to be the rightful monarch of the United Kingdom does not depend on whether any medieval monarchs of England or Scotland were of legitimate birth. Her claim of right to be queen goes back only as far as the invasion and revolution in 1688. She claims to be the rightful heir according to the rules and laws of succession established by the invaders and revolutionaries of 1688, no more, no less.
If someone accepts that the "Glorious Revolution" of 1688 was totally right, then Elizabeth II is the 100 percent legal and rightful sovereign of the United Kingdom. If someone does not accept the "Glorious Revolution" of 1688 was totally right, then there are numerous other persons with claims to be the rightful monarchs, and the question of which medieval English and Scottish royalty was of legitimate birth is then important to selecting the true rightful heir.