Theory of O'Connell descent
In 2025,
I formed a possible extraordinary theory that
my ancestor
George Cashel (born 1807)
may descend somehow from
the family of
Daniel O'Connell, "The Liberator"
and his wife and cousin
Mary O'Connell.
I thought at one point that we had an actual suspect
in the wider O'Connell family - a named parent for George Cashel.
But the suspect is now ruled out.
We have no named suspect, but the DNA is still pointing to this family.
We may be nearly on the end game of this long hunt.
Background: George Cashel descends from Blennerhassett
The background is that my ancestor
George Cashel (born 1807)
emerged in some irregular way from the landed gentry Blennerhassett family of Co.Kerry.
Something like an affair or a runaway marriage in about 1806.
This was already known by my family, but it took decades to prove
that he is in fact closely related to the Blennerhassett Baronets family.
See the proof of connection to the Blennerhassett Baronets family.
I believe I have proved
from documents and DNA
that George Cashel must descend somehow from
Robert Blennerhassett (died 1765),
father of
Sir Rowland Blennerhassett, 1st Baronet.
The most likely theory is that
George Cashel is the natural son of one of
six Blennerhassett men,
namely
the five sons
of the 1st Baronet,
and their 1st cousin.
That is, six grandsons of Robert Blennerhassett.
In 1806, 4 of the 6 men were married some years.
One was recently married in 1805.
Another was unmarried and married in 1808.
Something irregular happened.
One imagines it would be the old story:
A wealthy Blennerhassett man, perhaps married, has a brief affair with a lower class woman,
and then leaves her with the baby.
However, this page suggests something much more exotic may have happened:
A wealthy Blennerhassett man has an affair with a woman of his own class.
Let us lay out the evidence.
The theory begins with
Sheila O'Connell,
who has strong, unexplained DNA matches with multiple parts of the family below
George Cashel.
- Sheila O'Connell is a
DNA match (through unknown line) of (Blennerhassett Cashel, 1st marriage):
and of (Blennerhassett Cashel, 2nd marriage):
and of (Cashel of Alaska line):
- These DNA matches are pretty big. They indicate a common ancestor around 1800.
- The DNA matches do need explaining. But this by itself is not unusual.
Lots of DNA matches need explaining, and often are never explained.
- Normally I would not start with DNA matches and search for an explanation, because you never find one.
I go the other way. Construct a theory and then see if DNA matches support it.
- However, this one is different.
Systematically going through all shared matches groups
of all my people
on Ancestry suggests
Sheila O'Connell as the strongest unexplained group of matches in all my George Cashel descendant accounts.
So it is worth a closer look.
- How could we be related to Sheila?
- Looking at my family:
-
The DNA matches are spread across different sons of George Cashel
(and two different wives of one of the sons),
so therefore
the common ancestor must be through either George Cashel (Co.Kerry) or his wife (Co.Tipperary).
- Looking at her family:
-
Looking at her ancestors, it seems
the match must be through her
O'Connell or
Leyne lines,
both
in Co.Kerry.
- I discover to my surprise that her O'Connell family
is the Daniel O'Connell family of Kerry.
The likely lines (O'Connell and Leyne) are linked to Blennerhassett
- Looking at Sheila's family, I quickly see that her ancestors through O'Connell and Leyne
are deeply connected with Blennerhassett both socially and by blood.
This is now starting to look interesting.
- First, by blood. She actually descends in
two different lines
from early, 17th century Blennerhassetts.
But that is too far back to
explain the strong modern DNA matches.
The common ancestor must be more recent.
- She does not directly descend from the Blennerhassett Baronets branch in any way.
So that is not the answer to the DNA matches.
- This raises the extraordinary possibility that
this is George Cashel's parent
who is not the Blennerhassett Baronets line.
-
Have we found the line of George Cashel's mother?
That is, his mother is not a lower class woman.
Instead she is an upper class or upper middle class woman from this branch,
which we know is socially connected with the Blennerhassetts.
She has an affair with a Blennerhassett man from the Baronets branch, and
they are George Cashel's parents.
O'Connell fits better than Leyne
- Looking at the Leyne line,
it is hard to see how a mother for George Cashel could fit in.
Maurice Leyne, MD, marries in 1786, which is a bit late for him to have a daughter
who is George Cashel's mother.
There is no candidate.
Maybe Maurice has a niece that would fit.
We will keep looking.
- Over in the O'Connell line, we are looking at the family of
Thomas O'Connell, MD.
The dates and general layout fit much better to have a daughter who
is George Cashel's mother.
- There is some uncertainty about the number and names of the daughters of Thomas O'Connell, MD,
including an unnamed daughter who
married Patrick O'Mara.
- Could George's mother be an O'Connell, a sister of Mary?
Could Daniel O'Connell be our ancestral uncle?
What a discovery that would be.
As soon as I investigated
my biggest unexplained DNA match, Sheila O'Connell,
I was amazed to discover she
is listed under
O'CONNELL
in
[Burkes Irish, 1976].
She is a direct descendant of
Daniel O'Connell,
who I already knew was socially connected to the Blennerhassetts:
- I had known for decades that
Jane Blennerhassett
was grandmother of Mary O'Connell, wife of Daniel O'Connell.
-
I knew about the dramatic
1813 and
1832
O'Connell duels with Blennerhassetts.
-
I knew about Daniel O'Connell
dining with the 1st Baronet in
1816,
and other Blennerhassett mentions in O'Connell letters.
-
I had already held in my hands
an 1820 letter from Daniel O'Connell
in the Blennerhassett Baronets family.
-
So a DNA match to the O'Connell family
was immediately setting off alarms.
Is George Cashel's mother an O'Connell?
But then why is he called Cashel?
We may have to park that and look closer at O'Connell.
The evidence then got more exciting.
We discovered that
these specific O'Connells (the Mary O'Connell family)
are linked to
the specific Blennerhassetts we are interested in
(the Blennerhassett Baronets).
- 2nd cousin:
- 1st cousin:
-
Thomas O'Connell, MD, died in 1785.
-
Ellen Tuohy then married 2ndly in 1803 to
Henry Blennerhassett,
1st cousin of
Sir Rowland Blennerhassett, 1st Baronet.
- This is quite something.
This means that after 1803, Ellen's unmarried daughters (and other female relations)
are a lot more likely to be
socialising with the 1st Baronet's sons.
And hence an affair could happen around 1806.
- Quite a discovery.
This is beginning to look beyond coincidence.
On 12 Nov 2025,
I discovered the tragic 1806 story of
Kitty Tuohy.
She is part of this family, a 1st cousin of Mary O'Connell
through her mother Ellen Tuohy.
In 1806,
Kitty had accepted the hand of a young lawyer,
a friend of her cousin's husband
Daniel O'Connell.
But then, pressurised by friends, he rejected her.
She
fell into deep depression.
She
died of depression and heartbreak (looks like suicide) on 2 Nov 1806.
It is incredible that there is such a dramatic, and apparently unpublished, story in Daniel O'Connell's life.
And in the exact year, 1806, that we are looking for such drama to explain George Cashel.
For a while I thought this must be our story.
That the story was likely sanitised,
and in fact Kitty Tuohy got pregnant by a young Blennerhassett man, gave birth and then killed herself.
The baby was adopted and became George Cashel.
Consider:
- One of our
six Blennerhassett men
is indeed a young lawyer
and he is connected to Daniel O'Connell.
He is "Black Arthur" Blennerhassett, of Blennerville.
He was born in 1776, and entered King's Inns in 1794.
Daniel O'Connell was born in 1775, and entered King's Inns in 1795.
As two Kerry men studying law in Dublin, of course they knew each other from then.
- Arthur Blennerhassett in fact socialised with the family.
He
must be "Arthur Hassett" who is mentioned in a letter as dining with the
O'Connell family in August 1805.
- Arthur was married at this time, which would explain the rejection.
-
So we had suspects for both mother and father of George Cashel!
-
What are the odds that DNA led us into this family,
and then we found a tragic story of 1806 in this family?
However:
- The story makes no mention of pregnancy.
- The story says the man died unmarried, which does not fit Arthur, or any of our
six Blennerhassett men.
- The DNA matches seem too strong if the connection is as far back as Tuohy.
In the end, we found that, perhaps surprisingly, the Kitty Tuohy story is not our story.
On 2 Dec 2025,
I discovered that Kitty's doomed relationship was with
James O'Regan.
- James O'Regan
did indeed die unmarried.
-
O'Connell letters clearly show that Kitty is not pregnant.
In a letter of
19 August 1806 (and other letters discussing Kitty at that time)
there is no mention of Kitty's pregnancy.
And there would be.
-
The story of rejection in love by an unmarried man is true.
-
The 1806 story was indeed a tragedy,
but it is not the origin of George Cashel.
We then found more lots more DNA matches all throughout
the O'Connell/Tuohy/Leyne family.
The matches are with these three branches of my family:
- Blennerhassett Cashel, 1st marriage.
- Blennerhassett Cashel, 2nd marriage.
- Cashel of Alaska line.
Clearly these matches are all through George Cashel of Co.Kerry,
not through his wife of Co.Tipperary.
And they are
not the Blennerhassett Baronets line.
They are his mother's line,
which is the upper class or upper middle class family
of O'Connell/Tuohy/Leyne,
socially linked to the Blennerhassetts.
We will show these matches now in a table.
We have many O'Connell/Tuohy/Leyne DNA matches.
What is the common ancestor of all our DNA matches?
It is, precisely, the Thomas O'Connell, MD, family.
Here is a table of all our DNA matches,
their centimorgan (cM)
matches with the three lines of my family,
and their various lines of descent from Thomas O'Connell, MD.
| Name of DNA match |
Match with
Blen 1st marriage |
Match with
Blen 2nd marriage |
Match with
Cashel of Alaska |
Mary O'Connell descent |
O'Connor descent |
| Sheila O'Connell |
26 cM |
28 cM |
Match exists
Unknown cM |
Thomas O'Connell, MD
Mary O'Connell
John O'Connell, MP
|
Thomas O'Connell, MD
O'Connor
Leyne |
| Thomas Childers |
28 cM |
29 cM |
Match exists
Unknown cM |
Thomas O'Connell, MD
Mary O'Connell
John O'Connell, MP
|
Thomas O'Connell, MD
O'Connor
Leyne |
| Helen Crowther |
13 cM |
|
9 cM |
Thomas O'Connell, MD
Mary O'Connell
FitzSimon |
|
| Pat Crowther |
12 cM |
|
|
Thomas O'Connell, MD
Mary O'Connell
FitzSimon |
|
| Julia King |
12 cM |
|
|
Thomas O'Connell, MD
Mary O'Connell
John O'Connell, MP
|
|
| Richard King |
11 cM |
|
|
Thomas O'Connell, MD
Mary O'Connell
John O'Connell, MP
|
|
| Barbara Huth |
10 cM |
|
|
|
Thomas O'Connell, MD
O'Connor
Thomas O'Connor |
| Alix Good |
|
9 cM |
|
|
Thomas O'Connell, MD
O'Connor
Leyne |
The fact that Sheila O'Connell and Thomas Childers
have
multiple descents from Thomas O'Connell, MD,
would explain the higher cM matches.
If the common ancestor of our DNA matches is Thomas O'Connell, MD, and his wife,
does that mean Cashel must branch off in
exactly that generation?
- Could Cashel branch off earlier? Answer: Yes, but less likely.
- Cashel could descend from some earlier branch, like Tuohy.
And then we are all DNA related.
But we are looking for the most recent connection to explain the DNA matches,
especially the very strong Sheila O'Connell matches.
The DNA seems too strong to be an earlier branch.
This was always the problem with the Kitty Tuohy theory.
- Could Cashel branch off later? Answer: No.
- Could Cashel descend from one of the branches below Thomas O'Connell, MD?
One might think so, since we are all still DNA related.
But the dates do not allow it.
The dates mean that lower generations cannot be mother of George Cashel.
It has to be this generation or (less likely) earlier.
Conclusion:
George Cashel's mother
is most likely a sister of Mary O'Connell.
That would explain the DNA.
And it would explain (through her mother Ellen)
how she got together socially with Blennerhassett.
But can we find a document to prove it?
The daughters of Thomas O'Connell, MD,
in
[Burkes Irish, 1976].
It may be that George Cashel's mother was listed
in
[Burkes Irish, 1976]
all along, but I could not see it.
Thomas O'Connell, MD, has been on my family tree over 30 years,
because his mother was Blennerhassett,
and the Blennerhassett - Mary O'Connell connection was interesting.
Here he is on my offline Blennerhassett tree in 1992.
See also
screenshot
of him on my site in
1999.
In 2025, I found evidence that Thomas O'Connell, MD, may be my ancestor.
That George Cashel's mother was an O'Connell, his daughter.
In all the decades, I never suspected that for a minute.
Kitty Tuohy is not George Cashel's mother,
but the DNA still points to this family,
probably to a sister of Mary O'Connell.
We note that it does not point to anyone called Cashel.
There is no Cashel line in this family.
Highly likely that
the mother is not Cashel.
Neither parent of George Cashel is Cashel.
So what is Cashel? An invented surname?
Or an adopted surname?
We think it must be an adopted surname.
In fact, we have a suspect for the adopted Cashel family.
And the suspect may be linked to this O'Connell line.
- The suspect for the adopted family
is the
Stephen Cashel family of Tralee.
- George Cashel being adopted by them
would explain many things.
-
It would explain George's middle initial "S."
-
It would explain his attachment to the name "Agnes" for his daughters. Agnes Noonan would be his adopted mother.
- An adopted family would
explain why George Cashel's descendants do not DNA match any Cashel in the world
- which otherwise is hard to explain.
George Cashel is not a Cashel.
(He is in fact a Blennerhassett.)
- Finally, there is thin evidence this family is linked to this O'Connell line.
"Nelly Hassett" sponsors the baptism of their child in 1815.
This looks like Ellen Tuohy,
now
Mrs. Ellen Blennerhassett.
She may in fact be the grandmother of George Cashel.
- Conclusion: We have a strong suspect for an adopted family.
And some evidence linking this adopted family
to the Tuohy/O'Connell family.
- But can we find a document to prove it?
- One caution:
It is strange that no one from George's adoptive family ever turns up later in his life.
But he did move far away.
I had already discovered this George Cashel's baptism by
Jan 2004
(when my father was alive).
I could not see how it could be our George though.
It did not make sense.
Note I had not yet discovered it in
Aug 2003.
Baptism of Jane Cashell, 30 Dec 1815,
sp Nelly Hassett.
Our current theory would be:
- One of our
six Blennerhassett men
had an affair around late 1807 with some girl in the O'Connell/Tuohy family.
Someone of his own class and social circles.
- The DNA suggests it was most likely a sister of Mary O'Connell.
- The girl got pregnant and gave birth probably in early summer 1808.
-
The baby was adopted by Stephen Cashel and his wife Agnes Noonan, and
baptised Catholic as George Cashel in July 1808.
- It is interesting that my family remembered Blennerhassett, but not the much more famous
Daniel O'Connell.
But maybe because George was a Blennerhassett,
while Daniel O'Connell's relationship is less direct.
Let us pause and see what an incredibly lucky break this O'Connell link is.
For 40 years I struggled to find what Blennerhassetts George Cashel descends from.
At last, after endless work, I find it is the Blennerhassett Baronets family.
But that does not mean I get to find out what happened.
The father's family is likely to be sterile ground for documents.
A man has a brief affair and walks away.
He does not talk about the baby he fathered.
His family never see it.
And indeed I hunted through Blennerhassett Baronets papers at length and found nothing.
But the mother's family is different. They would know. They would see the baby.
They might help raise the baby.
But my big problem was they were likely to be lower class.
A servant girl, maybe.
A family that left no papers.
So what a lucky break this is.
If it is the O'Connells, this is a family so rich in papers
it would be hard to read them all.
This is an incredibly lucky break.
It could have been different.
But it looks like maybe this can be solved after all.
Lots more work to be done.
But we may be nearing the end of the hunt.
Mary O'Connell, who married Daniel O'Connell.
Is her sister George Cashel's mother?
W.T. Cosgrave is my granduncle.
The O'Rahilly is my great-granduncle.
Am I discovering that
Daniel O'Connell
is
my great-great-great-great-granduncle?
