The Blennerhassett problem

There has been one epic problem in all of my family tree research - the Blennerhassett problem. This is the problem of how our ancestor George Cashel (born 1807) descends from the Blennerhassett family. I first became aware of our possible Blennerhassett descent in 1985.

I am trying to prove a story from 1807.

George Cashel's RIC record.
Showing that he was recommended by "A. Blennerhasset, J.P." when he joined the County Constabulary in 1828.

George Cashel is written "George Blennerhassett Cashel" on the marriage cert of his son Blennerhassett Cashel in 1869.
See full size.

Detail from grave of George Cashel's son Blennerhassett Cashel.

The parents of George Cashel are not that far back.
They are Ahnentafel number 88 and 89 (if I am number 1).
There are 64 people in that generation, numbered 64 to 127.

The search from 1985

The Blennerhassett descent in the notes of my grand-aunt Pat Lavelle.
Pat died in 1966, before I was born.
I discovered her notes in 1985, and set off to prove the Blennerhassett descent.

This brief note in the BLENNERHASSETT entry in [Burkes Irish, 1976] by Brian Fitzelle first made me realise in 1985 that my Blennerhassett line might connect to the World family tree.

U2 at Live Aid in 1985 - the summer when my lifelong quest for Blennerhassett began.

Me at New Ballyseedy in 1985, at the start of the life-long hunt for Blennerhassett.
It later turned out that my ancestors never lived in this building.

Me at the rear of Blennerville House in 2022.
This is probably my actual ancestral home.

According to the Baronets theory (which seems to be true) my ancestors did not live at New Ballyseedy. They lived at Ballycarty and Old Ballyseedy and Castle Conway (all in ruins) and (if we descend from the 1st Baronet, which is likely) Stephen St, Dublin (unknown house, might survive) and Blennerville House (survives) and Churchtown House (survives).
According to the Letitia of Tarbert theory (which I have abandoned) my ancestors did not live at New Ballyseedy either. Under that theory, they would have lived at Ballycarty and Old Ballyseedy and Castle Conway (all in ruins) and Tralee Castle (demolished 1826) and Tralee Rectory (demolished 1995).

Letitia Blennerhassett in popular culture

Due to my friendship with the cartoonist and artist John Chambers, a mythical version of our supposed ancestor "Letitia Blennerhassett" has entered popular culture. John has followed the Letitia Blennerhassett story since the 1980s, and, loving her name, has included her in various of his creations.

Post, 23 Jan 2013, by Granny Samurai on Facebook.
"Granny Samurai in her Sunday Bonnet. She took First Prize on ladies day at Ascot. Just grabbed it right out of Laetitia Blenner-Hasset's lobster-like grip. Megawocka!"

John writes a joke letter to the Financial Times in 2008.
"How the Emerald Isle was turned blue" (and here), Financial Times, 22/23 Mar 2008.
"During his years in Japan (1891-1904), Lafcadio Hearn corresponded with a scholarly neighbour of his back in Ireland, one Letitia Blennerhassett. Though largely forgotten today, she was in her time a formidable scholar of the Irish language, collecting and translating a great deal of folk tales that would otherwise have been forgotten."
This letter was published, but the data is entirely made up.

The baptism

For many years, I searched for George Cashel's baptism around 1807, and I could not find it.
Of course I suspected it was burnt in 1922.
I thought he could easily be baptised CoI. And the majority of Co.Kerry CoI parish records from the 1807 period were burnt in 1922, including records of a fairly likely church, Killarney CoI church (near Churchtown House).

However, I have come round to suspect that I have been looking at his baptism all along, but could not recognise it.
That he is George Cashell, baptised in 1808 in Tralee RC church, either the biological or adopted son of the Stephen Cashel family of Tralee. His baptism was always there, but it could not solve my problem.

Baptism of George Cashell, 24 July 1808, Tralee RC church.

What we suspect is George Cashel's baptism on my website in Jan 2004.
It seems I had already discovered it by 2004, but I could not see it. It did not make sense.

The 1821 census

For many years, I bemoaned the destruction of the 1821 census. Almost all of the 1821 census was burnt in 1922, including the whole census for Kerry.
George Cashel was age 14 in 1821, so I thought the 1821 census might explain who his parents were, or maybe just who his mother was.

But if George is the biological or adopted son of the Stephen Cashel family of Tralee, then even if the census had survived, it could not solve my problem.

This is what could have survived:
The 1821 census entry for a 15 year old "George Reilly" and his family in Co.Cavan.

The 1922 fire

The Public Record Office, Dublin, before it was burnt by Irish "patriots" in 1922.
They burnt the (highly incomplete) 1813 census, the 1821 census, 1831 census, 1841 census and 1851 census.
(The 1861 and 1871 and 1881 and 1891 censuses were also destroyed separately, for various stupid reasons.)
See larger and full size.
From here.

For many years I thought the 1922 fire probably burnt forever who George Cashel was. The fire burnt the 1821 census which I thought would probably have solved the Blennerhassett problem immediately. I also thought it likely burnt his baptism record.
Now I suspect the baptism survived, and the census would not help. So I am not sure what impact the fire had. It definitely burnt many wills on the Blennerhassett side and O'Connell side. And lots of historical information relating to George Cashel's life was lost. But did it prevent solving the problem? I do not know.
It may be that the 1922 fire broke my link to pre-1700 Ireland and England. Or maybe it did not. I do not know yet.

DNA was the breakthrough

DNA was the new thing that moved the problem forward, disproving the Letitia theory, and proving the Baronets theory. DNA has now proved which branch of Blennerhassett we descend from. But the details of exactly how remain unknown.

My DNA match with Eileen Owen.
My own DNA, in every cell of my body, carries evidence of my Blennerhassett ancestry.

Current status

Theory of our descent from Blennerhassett explains in detail the current status of this problem.
What follows is a summary.

After 35 years, the Blennerhassett Baronets theory

After 35 years of research, and many dead ends, in 2020, DNA testing finally proved that we descend somehow from the Blennerhassett Baronets branch.

See proof of our descent from the Blennerhassett Baronets family. I call it as proved that our ancestor George Cashel (born 1807) descends somehow from Robert Blennerhassett (died 1765) and his wife Frances Yielding. Nothing else explains the DNA plus other evidence.

How exactly he descends from Robert and Frances remains to be seen.

After 40 years, the O'Connell theory and the Stephen Cashel theory

In 2025, I started to construct evidence of our descent from the O'Connell family. This finds DNA evidence that George Cashel is closely related to the O'Connell/Tuohy family, the family of Mary O'Connell who married Daniel O'Connell. This family were connected to the Blennerhassett Baronets family socially and by blood.

At the same time, since 2025, I have been gathering evidence of our descent from the Stephen Cashel family. This finds a Cashel family that very much looks like George Cashel's family, either biological or adopted. This family also descends from an unknown line of the Blennerhassetts (maybe the Baronets line).

We now have three main strands of evidence. A mountain of clues, waiting to be sewn together into one narrative that explains it all. I think we are nearing the home stretch.