O'Malley Group 3 update Part 1: Groups 3a1 to 3d (July 2025)

Group 3 consists of those O'Malley's who belong to one of the branches below M222, a DNA marker common in northwest Ireland in particular and associated with the semi-mythical figure of Niall of the Nine Hostages. There are currently 8 subgroups (3a to 3g) and there is strong evidence that Group 3a represents descendants of the O'Malley clan of Mayo, as described in the Irish Medieval Genealogies. Group 3a is the largest group in the project and will be discussed separately but this article (in two parts) deals with the smaller subgroups. Part 1 covers Group 3a1 to Group 3d. Part 2 covers Groups 3e to 3i.

As discussed in recent posts, the evaluation of each subgroup addresses the topics outlined in the figure below. Each topic is assessed using evidence derived from the sources in the text boxes to the right ...

Group 3a1 - Clonbur, Galway, Ireland?

There are only 3 men in this group and the surnames are O'Malley (x2) & Malia (x1). 

Group 3a1 on the project's Y-DNA Results Page

Two of the men have upgraded to the Big Y test and thus appear on the Time Tree, where they sit on the branch characterised by the DNA marker BY205502. The age estimate for this branch is 1382 AD, and thus Group 3a1 has been carrying the O'Malley surname for about 650 years. 

However, we do not know what happened before this time, and given that surnames were formed about 1000 years ago in Ireland, this leaves a gap in our knowledge of about 350 years. And given that the chances of a Surname / DNA Switch (SDS) are about 1-2% per generation and 33-55% over the last 1000 years, consequently the chances of there being an SDS prior to 1382 are about 12-19%.

If there was an SDS, we do not have any firm clues (either from the Time Tree, or the Y-DNA matches of the group members) regarding what the surname was prior to 1382 AD. All neighbouring branches were formed prior to the period of surname emergence in Ireland (about 950 AD - 1150 AD).

Most of the people on neighbouring branches have Irish origins. Information supplied by one of the group members indicates that a possible ancestral homeland for this group may have been Clonbur, county Galway.

Time Tree showing branch BY205502 (red icon).
The period of the emergence of surnames in Ireland is marked on the timescale by the green bar.
(click to enlarge)

Group 3b - Scots-Irish? Gallowglass? no SDS

The 5 members in this group have several interesting variants (Melly & Mellen) as well as the more familiar variants of Maley & O'Malley.

Group 3b on the project's Y-DNA Results Page

Two of the 5 men have upgraded to the Big Y test and thus appear on the Time Tree, where they sit on the branch characterised by the DNA marker BY170664. The age estimate for this branch is 1098 AD, and thus Group 3b has been carrying the O'Malley surname (or variant) for about 1000 years. This suggests that there has not been a Surname / DNA Switch (SDS) over this time period, and therefore this particular group may represent a very ancient branch of the broader O'Malley clan.

Given that Big Y test-takers on neighbouring branches (below FGC71316) have either Irish ancestry (24 men) or Scottish ancestry (13 men), and that one of the members of this group has an EKA (Earliest Known Ancestor) from Scotland, and another has ancestral origins in Donegal, I wonder if the members of this group represent descendants of Gallowglass mercenaries that were shipped from Scotland to northwest Ireland to help with ongoing wars and faction fighting around 1000 years ago. Did they adopt the O'Malley surname as a sign of loyalty to the clan they were fighting for?

Another (or related) possibility is that this group is somehow related to a Scottish surname that sounds like Malley, such as Milloy, Melley, or Mellen.

Time Tree showing branch BY170664 (red icon). 
The period of the emergence of surnames in Ireland is marked on the timescale by the green bar.
(click to enlarge)

Group 3c - Melloy (England? Scotland? Ireland?)

This group only consists of two people - a Melloy and a Craig.

Group 3c on the project's Y-DNA Results Page

Both men have done the Big Y test and the Melloy man sits on branch A10680 (red icon below) whereas the Craig man sits on a sub-branch 3 steps below this, namely BY82803. Thus, the common ancestor of both men passed down the A10680 DNA marker to them both, and this has an age estimate of 517 AD, well before the Surname Emergence Era (950-1150 AD), so technically these men should not really be grouped together as their common ancestor is >1000 years old.

Time Tree showing branch A10680 (red icon). 
The period of the emergence of surnames in Ireland is marked on the timescale by the green bar.
(click to enlarge)

Without another Melloy with comparative Big Y data, we cannot say how long the Melloy surname has been associated with this particular DNA signature. However, there is an exact Melloy match among the Melloy man's DNA matches ... but, this match has only tested to 37 markers. If he did the Big Y test, it is likely that both Melloy men would form a new branch somewhere below A10680. And this likelihood is further supported by the fact that (comparing their EKAs) it seems that their MRCA (Most Recent Common Ancestor) could not be any closer than Owen Melloy, born c.1810 in Ireland, which would mean that they are probably no closer than about 4th cousins (assuming they were both born about 1960, and allowing 30 years per generation).

An exact Melloy match (with a Genetic Distance of zero)

The origins of Group 3c are very difficult to pin down.

• The Group 3c Melloy man has an EKA from Ireland, and his Melloy exact match has an EKA from England. 
• Neighbouring branches are noteworthy for a group of Craig men (who have carried that name since about 1500 AD) and a group of men called Kilcoyne (who have also carried that name since about 1500 AD). The Craig men could have Scottish or Northern Irish origins, and the Kilcoyne men are associated with a very specific surname distribution that suggests origins in counties Galway or Mayo (see map inset above). 
• The Group 3c Melloy man's other matches are not very informative as he has a vast number of matches at each level of comparison, indicating that Convergence is probably present and a lot of his matches are much more distantly related than at first appearances.

High numbers of matches indicate a strong probability that Convergence is present

There are also limited clues from surname dictionaries and surname distribution maps. It could be from Ireland, from Scotland, or from England.

So it is not possible at this point to say where the Melloy man's ancestors came from. 

Group 3d - the Molloy Clan of Firceall

The single man in Group 3d is a Malloy, with an EKA called Molloy. His Big Y results indicate that he sits on the BY18029 branch of the Tree of Mankind, and this branch is right in the middle of a group of Molloy men who belong to Group 4 of the Molloy DNA Project. This group probably represents descendants of the Molloy's of Fircall / Firceall in county Offaly. 

Group 4 of the Molloy DNA Project - the Molloy's of Fircall, Offaly
The Group 3d man is on line 32

This group of Molloy men share a common ancestor who passed on the DNA marker A11227 to them all (only the sub-branch BY11709 is shown in the diagram below). This A11227 marker is associated with a current age estimate of 1107 AD. So the Molloy name has been associated with this particular DNA signature for about 900 years (at least) and this brings it back into the Surname Emergence Era (950-1150 AD), so the likelihood of a Surname / DNA Switch is very low. Therefore, this DNA signature was probably passed on by the progenitor of the surname (or one of his immediate ancestors or descendants).

Time Tree showing branch BY11709 (last branch). 
The period of the emergence of surnames in Ireland is marked on the timescale by the green bar.
(click to enlarge)

You can see the associated medieval genealogy of the Molloy clan of Firceall here, and further details about the territory of Firceall here.

After writing the above summary, I found a Milley in the Ungrouped section whom I have now moved into this group, so there are now 2 men in Group 3d.

The next article will focus on Groups 3e to Group 3i.

Maurice Gleeson

July 2025