...maybe someone would like to help me figure this out. I was tracing pedigree number LXXIV in "Some Colonial Dames of Royal Descent" (pps. 307-9: Alfred the Great, King of England) from him down to my ancestors of interest, the Digbys (whose ancestry, incidentally, was also Anglo-Saxon through their paternal line). Everything went beautifully until I arrived at this particular Geni profile. At that point, the branch divided into what appears to be a duplication of some sort. Very doppelganger-like, it seems.
Alfred the Great, king of the Anglo-Saxons
Edward I "the Elder", king of The Anglo-Saxons
Louis IV, king of West Francia
Mathilde de France, Reine Consort des Deux-Bourgognes
Berthe de Bourgogne, reine consort de France
Odo II, count of Blois, Champagne and Chartres
Hawise de Bretagne, duchesse de Bretagne
Alain IV "Fergant" de Cornouaille, duc de Bretagne
Constance Alix de Penthièvre (MARRIED AFTER 1160) Alain de Rohan (d 1195), 3rd vicomte de Rohan
Alain IV, vicomte de Rohan (MARRIED) Mabile de Fougères
However, while his marriage to Mabel matches up correctly, in "Colonial Dames" he is described: ALAIN IV., Viscount de Rohan, Count of Brittainy, feudal Baron le Zouche, of Ashby -- and like this eerily similar profile (his double, apparently):
Alain la Zouche, Lord of Ashby la Zouche
is the father of one Roger la Zouche (spouse unnamed); no Geni profile; who in turn is the father of a "Jr.":
...described as having (like this Geni profile) a brother William La Zouche, of Belmeis who died in 1199,
and a wife, Lady Margaret: Margaret Bisset
With whom the line continues to the Digbys:
Sir Everard Simon Digby, Esq., alias Greenleaf
Sir Everard Rutland Digby, alias Greenleaf (MARRIED) Jacqueta Digbie (Ellys)
This Everard was the high sheriff of Rutland (1459, etc.), although it isn't indicated on his Geni profile.
From this point onward, the pedigree veers away from my direct ancestry. But it is plain to see that the whole line is almost perfect on Geni, the only exception being that peculiar La Zouche zig-zag with the absence of one Roger and the weirdness of the parentage of the younger Roger la Zouche.
It looks like Roger's father does not fit correctly as the son of Geoffrey I, Vicomte de Porhoët and I can't understand how that happened.
Wikipedia says, "Also of note: Alan de Porhoët, son of Odo I, was created Viscount of Rohan and was the founder of the House of Rohan...Alan de Porhoët, younger brother of Odo II, left for England and became Alan la Zouche, great-grandfather of two English Barons and great-great-grandfather of a third - see Baron Zouche."
However, Wikipedia doesn't have anything earlier than Alan la Zouche, 1st Baron la Zouche of Ashby son of Roger la Zouche, Lord of Ashby son of Sir Alan la Zouche, I son of Sir Roger La Zouche
And so it just circled me right back around to my original problem, the Porhoët aka La Zouche question. I will have to take a break before looking at it again.