The Irish Fitzgeralds are supposedly descendants of Maurice FitzGerald, who invaded Ireland in 1169 from Wales.
Working backwards in time, Maurice's paternal line is commonly described to have been the following:

However, several of these links in Maurice's genealogy seem questionable to me. But because each of these people has a different geographic origin, it is theoretically possible that DNA might be useful in pinpointing which, if any, is the root ancestor of the Irish Fitzgeralds.
(While there is no such thing as "Norman" or "Briton" or "Anglo-Saxon" DNA, certain haplotypes and haplogroups are more common among each population. Those are the indicators which might give us some clues.)

Following are a few comments about each relationship, and where the DNA trail might lead.

1) Maurice FitzGerald

Maurice was born in Wales, out of his mother Nesta. According to one website, Nesta was quite worldly:

Such stories might leave the paternal DNA of Maurice open to speculation right at the beginning of our search...

2) Gerald de Windsor

Gerald de Windsor is certainly the recognized father of Maurice FitzGerald. Gerald's initial fame came as castellan of Pembroke castle in extreme southwest Wales, as a retainer of Arnulf de Montgomery, younger son of the famous Norman knight Roger de Montgomery.

However, it strikes me as odd that Gerald became the castellan of a castle in distant Wales, if he really was of noble birth from Windsor. Perhaps Gerald was merely a local knight who rose to power. Keep in mind that it was only after the de Montgomery family was exiled from England in 1102 by King Henry I, that Pembroke Castle was bestowed to Gerald as his personal possession.

On the other hand, one fact which hints that maybe Gerald was of some higher-status birth is that he married Nesta, a daughter of a Prince of South Wales. But even that fact is peculiar, as Normans did not normally marry non-Normans: "Among a further 2,000 Norman families, the intermarriage rate was less than 5 per cent for four generations." [Michael Wood, In Search of England (Berkeley, U. of California, 1999)]

I'm trying not to speculate too much, but maybe Gerald's receipt of Pembroke Castle and his marriage to Nesta are connected events. Is it possible the marriage was brokered by Henry I (Nesta's paramour), as part of the redistribution of the de Montgomery lands, which would account for Gerald marrying "up" in class?

If Gerald is the root ancestor of the Fitzgeralds, his DNA is probably Norman if he was really descended from the ruling class. Or perhaps Briton if he was of local Pembrokeshire birth. Or to mention all the possibilities, even Anglo-Saxon if he was from a native family near Windsor.
(The linguistic source of the name "Gerald" appears to be Germanic, roughly translating to "spear ruler", although it seems to have been brought to Britain only by the Normans.)

3) Walter FitzOther

Walter FitzOther appears in the Domesday book of 1086, so he is clearly a real person. Domesday implies (without saying it outright) that he was keeper of the royal Windsor Forest.

Walter is claimed to be the father of Gerald de Windsor. But why? The noted skeptical genealogist J. Horace Round writing in 1902 raises a important point: Gerald's own grandson, the semi-famous chronicler, Gerald of Wales, never made such a claim. Only once did Gerald call his grandfather "Geraldus de Windesora". Is it possible that Gerald was merely from the Windsor area, and over the centuries, this link has mistakenly attached him to the actual "de Windsor" family of Walter FitzOther?

If Walter is the root ancestor of the Fitzgeralds, his DNA is most likely Norman. However, there is not yet any way to genetically distinguish the various ethnic groups of Normandy, especially since there is some debate on whether the invading Vikings were Norse or Danes, and because they intermixed with the local Gauls and Franks.

4) Dominus Other

It is claimed that Dominus Other was a Norman who came to England with Edward the Confessor, prior to 1066. (Which is entirely possible, since Edward was raised in the household of his grandfather, Richard, Duke of Normandy.)

But I have been unable to pinpoint where proof of Dominus' existence can be found, or why it is said he was the father of Walter FitzOther. Since "Dominus" in Latin means "Lord", is it possible that "Lord Other" was merely used as the generic name for the father of Walter Fitz("son of") Other, since the real name was unknown?

If Dominus is the root ancestor of the Fitzgeralds, his DNA is arguabley Norman, although the unusual name Dominus hints that maybe he is from further south. And to further confuse his origin, Dominus' last name has also been spelled as Otho.

5) Gherardo Gherardini

It is claimed that Gherardo Gherardini was the father of Dominus Other. And behold, Gherardo was not merely a run of the mill Norman, but he was a knight from Italy, descended from the Dukes of Florence!

The factual basis for this claim is a mystery to me, and strikes me as unbelievable. The earliest written comment on the Geraldine-Gherardini tie is found in 1440, in correspondence from Leonardo Aretino, Secretary of the Florentine Republic to James, Earl of Desmond:
"If it is true that your progenitors were Florentines by birth, as has been told us, and of the most noble and ancient family of the Gherardini, which even now is one of the most distinguished in this city, we have ample reason to rejoice and congratulate ourselves"
(Note that the tie was claimed by the Fitzgeralds, but not confirmed by the Florentines.)

The book "History of The Geraldines" written by Dominic O'Daly in 1655, has even more outlandish claims for the ancient origins of the Gherardini (leading back to Troy in the years B.C.), and seems to be the basis for all later popular descriptions of the Geraldine line. Is it possible that the supposed Gherardini-Geraldine connection merely sprouted over time because of a similarity in spelling and pronunciation, and a desire to have a grandly noble origin?

If Gherardo is the root ancestor of the Fitzgeralds, his DNA would lead back to Italy, a genetic crossroads, but a place where not many DNA studies have yet been carried out.

My personal opinion is this:

Why I have gone into such detail following the Fitzgerald ancestry, and how does it relate to genetics?
Simply, if modern day Fitzgeralds are truly descendents of Maurice FitzGerald, they would carry common DNA. This common DNA might then be used to pinpoint which of Maurice's forbearers is the true root ancestor, because of the following genetic facts:

(For an example of both the successes and difficulties in using DNA to determine geographic origins, see the research behind the BBC program, Blood of the Vikings.)

The FITZGERALD DNA project currently has 4 different haplogroups represented (R1b, I1a, E3b, J). These people are absolutely NOT genetically related to each other. It is possible that one of them may be a descendant of Maurice FitzGerald, but there is simply not enough data to even to begin to make such a claim.

One way to resolve the mystery is to test someone connected to the Duke of Leinster lineage, as they are direct descendants of Maurice FitzGerald.

UPDATE (September 2007):

A recent addition to the Fitzgerald DNA project claims to descend from a son of Maurice FitzGerald, specifically Maurice, founder of the Barron of Burnchurch line. He has posted his lineage here.

Relatedly, an interesting post discussing how certain Welsh families are said to descend from the FitzGeralds can be found here. In fact, there does seem to be a genetic similarity between those Welsh names, and the Barron DNA.

On the other hand, the Barron DNA does not match any other Fitzgeralds currently in the project.

ERRATA:

While putting this page together, I noticed several inconsistencies regarding various dates of birth, marriage and death for the early FitzGeralds. I've noted them separately here, since they are off-topic from the main focus of this page:

* Maurice FitzGerald's reported year of birth was 1100. If accurate, that would mean he invaded Ireland when was 69, which seems a bit old.
* A birth year for Maurice of 1100 would also mean that Gerald de Windsor and Nesta married EARLIER than 1100, since they had an elder son, William. However, it would make more sense that they were married later, specifically after 1102 when Pembroke Castle was transferred from Arnulf de Montgomery to Gerald. A marriage after 1102 would also make Maurice younger than an unlikely 69 when he invaded Ireland.
* Arnulf de Mongomery lived 1068-c.1118. He married sometime around 1100, which is when he sent Gerald de Windsor to Ireland to help arrange a marriage to Lafracoth O'Brien. Arnulf had a daughter named Alice de Montgomery, who married Gerald's son, Maurice FitzGerald. (A surprising pairing: the daughter of one man, to the son of another man who displaced him.) It's not clear when Maurice and Alice married, but one of their sons (another Gerald) was born 1150. This fact too seems to indicate a birth year for Maurice later than 1100.

First posted: 12/13/05
Last revised: 9/9/07