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OT: Baronet Rowland Blennerhassett
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Paulo Ricardo Canedo
2020-06-16 23:58:04 UTC
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This is an important addition to all the peerage books. Baronet Rowland Blennerhassett has traditionally been assigned no daughters. However, DNA tests have shown that he had a daughter, mother of George Cashel. Read https://humphrysfamilytree.com/Blennerhassett/proof.html and linked pages for details. In addition, a baptism has been found for Melisent Blennerhassett, as his daughter. She probably was George Cashel's mother but it's also possible that George's mother was a later daughter. This is one of the very few cases in which the peerage books were wrong and the family tradition was right.
John Higgins
2020-06-17 05:19:51 UTC
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Post by Paulo Ricardo Canedo
This is an important addition to all the peerage books. Baronet Rowland Blennerhassett has traditionally been assigned no daughters. However, DNA tests have shown that he had a daughter, mother of George Cashel. Read https://humphrysfamilytree.com/Blennerhassett/proof.html and linked pages for details. In addition, a baptism has been found for Melisent Blennerhassett, as his daughter. She probably was George Cashel's mother but it's also possible that George's mother was a later daughter. This is one of the very few cases in which the peerage books were wrong and the family tradition was right.
The accepted manner of referring to this gentleman is not "Baronet Rowland Blennerhassett", but instead "Sir Rowland Blennerhassett, 1st Baronet".

I have no comment on Mark Humphrys' theory that one of Sir Rowland's daughters (now suggested to be Melisent) was the mother (via an illicit affair with an unknown man) of Humphry's ancestor George Cashel, who later assumed the middle name Blennerhassett. [An interesting story...worthy of the tabloid news publications]

BTW it's inaccurate for you to say that "the peerage books were wrong". Even if the editors of BP had knowledge of this supposed relationship, they never would have considered it appropriate to make mention of an illegitimate son of a daughter of a baronet. And it's hardily an "important" addition to the peerage books...
Paulo Ricardo Canedo
2020-06-17 10:37:37 UTC
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Post by John Higgins
Post by Paulo Ricardo Canedo
This is an important addition to all the peerage books. Baronet Rowland Blennerhassett has traditionally been assigned no daughters. However, DNA tests have shown that he had a daughter, mother of George Cashel. Read https://humphrysfamilytree.com/Blennerhassett/proof.html and linked pages for details. In addition, a baptism has been found for Melisent Blennerhassett, as his daughter. She probably was George Cashel's mother but it's also possible that George's mother was a later daughter. This is one of the very few cases in which the peerage books were wrong and the family tradition was right.
The accepted manner of referring to this gentleman is not "Baronet Rowland Blennerhassett", but instead "Sir Rowland Blennerhassett, 1st Baronet".
I have no comment on Mark Humphrys' theory that one of Sir Rowland's daughters (now suggested to be Melisent) was the mother (via an illicit affair with an unknown man) of Humphry's ancestor George Cashel, who later assumed the middle name Blennerhassett. [An interesting story...worthy of the tabloid news publications]
BTW it's inaccurate for you to say that "the peerage books were wrong". Even if the editors of BP had knowledge of this supposed relationship, they never would have considered it appropriate to make mention of an illegitimate son of a daughter of a baronet. And it's hardily an "important" addition to the peerage books...
First, thanks for clarifying me on the correct way to refer to this aristocrat.
Second, George Cashel being grandson of Sir Rowland Blennerhassett is not only a theory. DNA has shown that it must be so. Also, Mark Humphrys's current thinking is that it was a runaway marriage, like in the family story, not an affair.
Third, I would say that this is an important addition because the peerage books show no daughters at all for Sir Rowland Blennerhassett.
John Higgins
2020-06-17 21:09:04 UTC
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Post by Paulo Ricardo Canedo
Post by John Higgins
Post by Paulo Ricardo Canedo
This is an important addition to all the peerage books. Baronet Rowland Blennerhassett has traditionally been assigned no daughters. However, DNA tests have shown that he had a daughter, mother of George Cashel. Read https://humphrysfamilytree.com/Blennerhassett/proof.html and linked pages for details. In addition, a baptism has been found for Melisent Blennerhassett, as his daughter. She probably was George Cashel's mother but it's also possible that George's mother was a later daughter. This is one of the very few cases in which the peerage books were wrong and the family tradition was right.
The accepted manner of referring to this gentleman is not "Baronet Rowland Blennerhassett", but instead "Sir Rowland Blennerhassett, 1st Baronet".
I have no comment on Mark Humphrys' theory that one of Sir Rowland's daughters (now suggested to be Melisent) was the mother (via an illicit affair with an unknown man) of Humphry's ancestor George Cashel, who later assumed the middle name Blennerhassett. [An interesting story...worthy of the tabloid news publications]
BTW it's inaccurate for you to say that "the peerage books were wrong". Even if the editors of BP had knowledge of this supposed relationship, they never would have considered it appropriate to make mention of an illegitimate son of a daughter of a baronet. And it's hardily an "important" addition to the peerage books...
First, thanks for clarifying me on the correct way to refer to this aristocrat.
Second, George Cashel being grandson of Sir Rowland Blennerhassett is not only a theory. DNA has shown that it must be so. Also, Mark Humphrys's current thinking is that it was a runaway marriage, like in the family story, not an affair.
Third, I would say that this is an important addition because the peerage books show no daughters at all for Sir Rowland Blennerhassett.
So...what should BP say regarding this "important" matter? "Sir Rowland also had a daughter Melisent who, according to DNA testing supporting family tradition, had a son George Cashel by a father whose name is not presently known." That would certainly be a first-of-its-kind entry for BP... :-)
wjhonson
2020-06-18 01:58:20 UTC
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Do I understand this DNA "proof" correctly in that, he uses a 15cm match to prove his line?

Please correct me if I am wrong.

15cms cannot be used in this manner for a connection only two hundred years in the past
John Higgins
2020-06-18 04:45:43 UTC
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Post by wjhonson
Do I understand this DNA "proof" correctly in that, he uses a 15cm match to prove his line?
Please correct me if I am wrong.
15cms cannot be used in this manner for a connection only two hundred years in the past
You are correct that Mark Humphrys uses a 15cm match to state that a connection with Sir Rowland Blennerhassett,1st Baronet, of Blennerville (b. 1741, d. 14.III.1821) has been established with his supposed grandson George Cashel (b. ca. 1807, d. 21.VI.1882).

Someone more familiar with DNA testing than I am will need to read through the details and make a judgment on this. Personally, I don't particularly care either way... :-)
Paulo Ricardo Canedo
2020-06-18 22:25:30 UTC
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Post by wjhonson
Do I understand this DNA "proof" correctly in that, he uses a 15cm match to prove his line?
Please correct me if I am wrong.
15cms cannot be used in this manner for a connection only two hundred years in the past
Actually, Mark noted in humphrysfamilytree.com/DNA/baronet.html that such matches are common for such relationships.
In addition, in the previous page I linked to, he explains how such matches didn't happen with the Letitia Blennerhassett of Tarbert theory.
Carl-Henry Geschwind
2020-06-19 15:09:00 UTC
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Post by Paulo Ricardo Canedo
Post by wjhonson
Do I understand this DNA "proof" correctly in that, he uses a 15cm match to prove his line?
Please correct me if I am wrong.
15cms cannot be used in this manner for a connection only two hundred years in the past
Actually, Mark noted in humphrysfamilytree.com/DNA/baronet.html that such matches are common for such relationships.
In addition, in the previous page I linked to, he explains how such matches didn't happen with the Letitia Blennerhassett of Tarbert theory.
The problem is not the 15 cM, the problem is the lack of triangulation.

What the first DNA test actually proves is that Meg Niemi is related to John Chute. The DNA test itself does not show how they are related - if they are (as claimed) fifth cousins once removed, then any one of Meg's 64 sets of 5-great-grandparents could be the same as one of John's 32 sets of 4-great-grandparents (a total of a bit more than 2,000 possible relationship paths). Do you know all of the ancestors of Meg and all of the ancestors of John back to the late 1700s well enough to be able to rule out any relationship other than through the Cashels and Blennerhassetts?

As Wikitree (yes, Wikitree) explains (at https://www.wikitree.com/wiki/Help:Triangulation), once you are beyond third cousins, you need triangulation before you can consider a relationship proven by DNA. That is, you need to see the same piece of DNA in two or more matches in order to establish the branch through which that piece of DNA has descended.

The match between Meg Niemi and John Chute is on GEDMatch, so we know the exact piece of DNA on which they match (on Chromosome 11). In order to prove that this match is because the Cashels are descended from the Blennerhassetts, you need another descendant of George Cashel (through a child other than the ancestor of Meg Niemi) who also matches on at least 7 cM of that segment on Chromosome 11, and you need another descendant of Rowland Blennerhassett (through a child other than the ancestor of John Chute) who matches on at least 7 cM of that segment.

Mark Humphrys offers some other DNA matches between Derval McGrath, Nuala Duggan, and "Bayly 10"; however, these tests are on ancestry.com (rather than GEDMatch) and thus do not give any segment information - in other words, for purposes of triangulation they are worthless. If he can persuade those test takers to export their ancestry.com results to GEDMatch, and then can show that the matches are also on that segment of Chromosome 11 - then he will have proven his claim. But as it is, the relationship between the McGraths and the Yieldings might be through a completely different patch than the relationship between Meg Niemi and John Chute.

Thus, despite what Mark claims, the relationship has not yet been proven - we know that Meg Niemi and John Chute are related, but the DNA has not yet proven that George Cashel and Rowland Blennerhassett are related.

--Carl-Henry
j***@gmail.com
2020-06-19 16:57:59 UTC
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Post by Carl-Henry Geschwind
Post by Paulo Ricardo Canedo
Post by wjhonson
Do I understand this DNA "proof" correctly in that, he uses a 15cm match to prove his line?
Please correct me if I am wrong.
15cms cannot be used in this manner for a connection only two hundred years in the past
Actually, Mark noted in humphrysfamilytree.com/DNA/baronet.html that such matches are common for such relationships.
In addition, in the previous page I linked to, he explains how such matches didn't happen with the Letitia Blennerhassett of Tarbert theory.
The problem is not the 15 cM, the problem is the lack of triangulation.
What the first DNA test actually proves is that Meg Niemi is related to John Chute. The DNA test itself does not show how they are related - if they are (as claimed) fifth cousins once removed, then any one of Meg's 64 sets of 5-great-grandparents could be the same as one of John's 32 sets of 4-great-grandparents (a total of a bit more than 2,000 possible relationship paths). Do you know all of the ancestors of Meg and all of the ancestors of John back to the late 1700s well enough to be able to rule out any relationship other than through the Cashels and Blennerhassetts?
As Wikitree (yes, Wikitree) explains (at https://www.wikitree.com/wiki/Help:Triangulation), once you are beyond third cousins, you need triangulation before you can consider a relationship proven by DNA. That is, you need to see the same piece of DNA in two or more matches in order to establish the branch through which that piece of DNA has descended.
The match between Meg Niemi and John Chute is on GEDMatch, so we know the exact piece of DNA on which they match (on Chromosome 11). In order to prove that this match is because the Cashels are descended from the Blennerhassetts, you need another descendant of George Cashel (through a child other than the ancestor of Meg Niemi) who also matches on at least 7 cM of that segment on Chromosome 11, and you need another descendant of Rowland Blennerhassett (through a child other than the ancestor of John Chute) who matches on at least 7 cM of that segment.
Mark Humphrys offers some other DNA matches between Derval McGrath, Nuala Duggan, and "Bayly 10"; however, these tests are on ancestry.com (rather than GEDMatch) and thus do not give any segment information - in other words, for purposes of triangulation they are worthless. If he can persuade those test takers to export their ancestry.com results to GEDMatch, and then can show that the matches are also on that segment of Chromosome 11 - then he will have proven his claim. But as it is, the relationship between the McGraths and the Yieldings might be through a completely different patch than the relationship between Meg Niemi and John Chute.
Just to clarify, you can use ancestry.com for a little more than this, and don't need to know or care if you are matching the same exact segment at times (although that certainly strengthens the case)

For the simplest case, if I have 22cm of matching with someone with, say an orphan with no paper history; and also see that we have 12 matches in common, and all 12 matches are related to me through a diverse set of my father's ancestors/cousins, none through my mother's relatives.... it certainly is good evidence that this unknown match is also related to my father. It doesn't really matter if he is related to each of the 12 on different segments. The same analysis can be done with grandfather, great-grandfather,etc; the weight of the evidence depending on how many descendants of how many different children you are matching in common.

--Joe C
c***@gmail.com
2020-06-19 17:41:25 UTC
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Paulo -

Carl is correct. You need triangulation of DNA matches to prove the Blennerhassett connection.

I recently used triangulation to prove my descent from a Revolution War ancestor, Eli Reynolds, of Delaware Co., NY and Athens Co., Ohio, who was born about 1734. My brother and I and two near cousins were tested. Between the four of us, we had DNA matches to descendants of all seven children of Eli Reynolds who are known to have left descendants.

To do triangulation effectively, you have to have the DNA of several of your known relatives to compare against several known descendants of an alleged ancestor. To do this well, you also need accurate genealogical records of both sets of families.

One match by itself proves absolutely nothing. Triangulation is an effective tool but it depends on having sufficient DNA and good family records. Also it assumes you are not dealing with something which can skew DNA results such as double descents from the same family. If you have a double descent from any family, it will show closer DNA matches to others descended from that family than typical. A similar thing occurs when two brothers married sisters or two first cousins married sisters.

DR
Paulo Ricardo Canedo
2020-06-20 00:54:39 UTC
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Post by Carl-Henry Geschwind
Post by Paulo Ricardo Canedo
Post by wjhonson
Do I understand this DNA "proof" correctly in that, he uses a 15cm match to prove his line?
Please correct me if I am wrong.
15cms cannot be used in this manner for a connection only two hundred years in the past
Actually, Mark noted in humphrysfamilytree.com/DNA/baronet.html that such matches are common for such relationships.
In addition, in the previous page I linked to, he explains how such matches didn't happen with the Letitia Blennerhassett of Tarbert theory.
The problem is not the 15 cM, the problem is the lack of triangulation.
What the first DNA test actually proves is that Meg Niemi is related to John Chute. The DNA test itself does not show how they are related - if they are (as claimed) fifth cousins once removed, then any one of Meg's 64 sets of 5-great-grandparents could be the same as one of John's 32 sets of 4-great-grandparents (a total of a bit more than 2,000 possible relationship paths). Do you know all of the ancestors of Meg and all of the ancestors of John back to the late 1700s well enough to be able to rule out any relationship other than through the Cashels and Blennerhassetts?
As Wikitree (yes, Wikitree) explains (at https://www.wikitree.com/wiki/Help:Triangulation), once you are beyond third cousins, you need triangulation before you can consider a relationship proven by DNA. That is, you need to see the same piece of DNA in two or more matches in order to establish the branch through which that piece of DNA has descended.
The match between Meg Niemi and John Chute is on GEDMatch, so we know the exact piece of DNA on which they match (on Chromosome 11). In order to prove that this match is because the Cashels are descended from the Blennerhassetts, you need another descendant of George Cashel (through a child other than the ancestor of Meg Niemi) who also matches on at least 7 cM of that segment on Chromosome 11, and you need another descendant of Rowland Blennerhassett (through a child other than the ancestor of John Chute) who matches on at least 7 cM of that segment.
Mark Humphrys offers some other DNA matches between Derval McGrath, Nuala Duggan, and "Bayly 10"; however, these tests are on ancestry.com (rather than GEDMatch) and thus do not give any segment information - in other words, for purposes of triangulation they are worthless. If he can persuade those test takers to export their ancestry.com results to GEDMatch, and then can show that the matches are also on that segment of Chromosome 11 - then he will have proven his claim. But as it is, the relationship between the McGraths and the Yieldings might be through a completely different patch than the relationship between Meg Niemi and John Chute.
Thus, despite what Mark claims, the relationship has not yet been proven - we know that Meg Niemi and John Chute are related, but the DNA has not yet proven that George Cashel and Rowland Blennerhassett are related.
--Carl-Henry
Occam's razor applies. There's no reason to complicate matters by supposing undocumented connections.
The Cashels used Blennerhassett as a middle and even first name and had a tradition of being descended from the Blennerhassetts.
In addition, Thomas Blennerhassett of Gortatlea said that George Cashel's mother must have been daughter of Sir Rowland Blennerhassett.
c***@gmail.com
2020-06-20 02:27:13 UTC
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The Blennerhasset connection can be conclusively proved by a well researched triangulated DNA project. There is nothing complex or complicated about such a project. It simply takes hard DNA evidence supported by known proven facts.

DR
Carl-Henry Geschwind
2020-06-20 02:36:36 UTC
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Post by Paulo Ricardo Canedo
Post by Carl-Henry Geschwind
Post by Paulo Ricardo Canedo
Post by wjhonson
Do I understand this DNA "proof" correctly in that, he uses a 15cm match to prove his line?
Please correct me if I am wrong.
15cms cannot be used in this manner for a connection only two hundred years in the past
Actually, Mark noted in humphrysfamilytree.com/DNA/baronet.html that such matches are common for such relationships.
In addition, in the previous page I linked to, he explains how such matches didn't happen with the Letitia Blennerhassett of Tarbert theory.
The problem is not the 15 cM, the problem is the lack of triangulation.
What the first DNA test actually proves is that Meg Niemi is related to John Chute. The DNA test itself does not show how they are related - if they are (as claimed) fifth cousins once removed, then any one of Meg's 64 sets of 5-great-grandparents could be the same as one of John's 32 sets of 4-great-grandparents (a total of a bit more than 2,000 possible relationship paths). Do you know all of the ancestors of Meg and all of the ancestors of John back to the late 1700s well enough to be able to rule out any relationship other than through the Cashels and Blennerhassetts?
As Wikitree (yes, Wikitree) explains (at https://www.wikitree.com/wiki/Help:Triangulation), once you are beyond third cousins, you need triangulation before you can consider a relationship proven by DNA. That is, you need to see the same piece of DNA in two or more matches in order to establish the branch through which that piece of DNA has descended.
The match between Meg Niemi and John Chute is on GEDMatch, so we know the exact piece of DNA on which they match (on Chromosome 11). In order to prove that this match is because the Cashels are descended from the Blennerhassetts, you need another descendant of George Cashel (through a child other than the ancestor of Meg Niemi) who also matches on at least 7 cM of that segment on Chromosome 11, and you need another descendant of Rowland Blennerhassett (through a child other than the ancestor of John Chute) who matches on at least 7 cM of that segment.
Mark Humphrys offers some other DNA matches between Derval McGrath, Nuala Duggan, and "Bayly 10"; however, these tests are on ancestry.com (rather than GEDMatch) and thus do not give any segment information - in other words, for purposes of triangulation they are worthless. If he can persuade those test takers to export their ancestry.com results to GEDMatch, and then can show that the matches are also on that segment of Chromosome 11 - then he will have proven his claim. But as it is, the relationship between the McGraths and the Yieldings might be through a completely different patch than the relationship between Meg Niemi and John Chute.
Thus, despite what Mark claims, the relationship has not yet been proven - we know that Meg Niemi and John Chute are related, but the DNA has not yet proven that George Cashel and Rowland Blennerhassett are related.
--Carl-Henry
Occam's razor applies. There's no reason to complicate matters by supposing undocumented connections.
The Cashels used Blennerhassett as a middle and even first name and had a tradition of being descended from the Blennerhassetts.
In addition, Thomas Blennerhassett of Gortatlea said that George Cashel's mother must have been daughter of Sir Rowland Blennerhassett.
Paulo:

Sure, so there is some family tradition. If you want to rely on that family tradition, fine by me. But it still has nothing to do with what the DNA test actually proves. As I said, the DNA test only proves that there is some genetic relationship between Meg Niemi and John Chute - there is no DNA evidence yet that demonstrates that the relationship is between Cashels and Blennerhassetts. If you want to say, as you did in your first post, that "DNA tests have shown that he [Rowland Blennerhassett] had a daughter, mother of George Cashel" (and not just that "family tradition says that he had a daughter, mother of George Cashel"), you need to do more work with the DNA. And this has nothing to do with Occam's razor - simply picking the one known or suspected relationship and saying that it (rather than one of the 2000+ potential other relationships) has to be the way they are related, without actually evaluating complete family trees or obtaining additional DNA evidence, is just jumping to a conclusion.

I'm not saying that the Cashel-Blennerhassett relationship doesn't exist or has been disproven - all I'm saying is that it is not yet proven via a DNA test.
John Higgins
2020-06-20 03:32:39 UTC
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Post by Paulo Ricardo Canedo
Post by Carl-Henry Geschwind
Post by Paulo Ricardo Canedo
Post by wjhonson
Do I understand this DNA "proof" correctly in that, he uses a 15cm match to prove his line?
Please correct me if I am wrong.
15cms cannot be used in this manner for a connection only two hundred years in the past
Actually, Mark noted in humphrysfamilytree.com/DNA/baronet.html that such matches are common for such relationships.
In addition, in the previous page I linked to, he explains how such matches didn't happen with the Letitia Blennerhassett of Tarbert theory.
The problem is not the 15 cM, the problem is the lack of triangulation.
What the first DNA test actually proves is that Meg Niemi is related to John Chute. The DNA test itself does not show how they are related - if they are (as claimed) fifth cousins once removed, then any one of Meg's 64 sets of 5-great-grandparents could be the same as one of John's 32 sets of 4-great-grandparents (a total of a bit more than 2,000 possible relationship paths). Do you know all of the ancestors of Meg and all of the ancestors of John back to the late 1700s well enough to be able to rule out any relationship other than through the Cashels and Blennerhassetts?
As Wikitree (yes, Wikitree) explains (at https://www.wikitree.com/wiki/Help:Triangulation), once you are beyond third cousins, you need triangulation before you can consider a relationship proven by DNA. That is, you need to see the same piece of DNA in two or more matches in order to establish the branch through which that piece of DNA has descended.
The match between Meg Niemi and John Chute is on GEDMatch, so we know the exact piece of DNA on which they match (on Chromosome 11). In order to prove that this match is because the Cashels are descended from the Blennerhassetts, you need another descendant of George Cashel (through a child other than the ancestor of Meg Niemi) who also matches on at least 7 cM of that segment on Chromosome 11, and you need another descendant of Rowland Blennerhassett (through a child other than the ancestor of John Chute) who matches on at least 7 cM of that segment.
Mark Humphrys offers some other DNA matches between Derval McGrath, Nuala Duggan, and "Bayly 10"; however, these tests are on ancestry.com (rather than GEDMatch) and thus do not give any segment information - in other words, for purposes of triangulation they are worthless. If he can persuade those test takers to export their ancestry.com results to GEDMatch, and then can show that the matches are also on that segment of Chromosome 11 - then he will have proven his claim. But as it is, the relationship between the McGraths and the Yieldings might be through a completely different patch than the relationship between Meg Niemi and John Chute.
Thus, despite what Mark claims, the relationship has not yet been proven - we know that Meg Niemi and John Chute are related, but the DNA has not yet proven that George Cashel and Rowland Blennerhassett are related.
--Carl-Henry
Occam's razor applies. There's no reason to complicate matters by supposing undocumented connections.
The Cashels used Blennerhassett as a middle and even first name and had a tradition of being descended from the Blennerhassetts.
In addition, Thomas Blennerhassett of Gortatlea said that George Cashel's mother must have been daughter of Sir Rowland Blennerhassett.
You should refrain from invoking Occam's razor when it doesn't really apply. in fact, there may be a simple explanation for the Cashels' use of the Blennerhassett name that I pointed out to you offline more than two months ago. I'll repeat it here:

"There is no doubt that the Cashels and their descendants used Blennerhassett as a given name and a middle name. But that doesn't mean that they were necessarily descended from that family. It's at least equally possible that George "Blennerhassett" Cashel assumed the the name as a gesture of respect for "A. Blennerhassett" who recommended him for the RIC. (BTW only a single record is given indicating that George Cashel actually used the Blennerhassett name throughout his long life. See if you can find it.. :-) )"

I hope you can now accept the fact that DNA testing has NOT yet proved this descent. And nobody has even suggested "supposing undocumented connections", to use your phrase above. A "family tradition" is just that, a tradition - not evidence at all of an actual biological connection.

As I told you back in April, "it pays to maintain a healthy dose of skepticism in cases like this". You seem to lost any sense of skepticism in your rush to accept this as a proven descent. That's not Occam's razor - it's simply bad judgment.
Paulo Ricardo Canedo
2020-06-20 22:21:27 UTC
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Post by John Higgins
Post by Paulo Ricardo Canedo
Post by Carl-Henry Geschwind
Post by Paulo Ricardo Canedo
Post by wjhonson
Do I understand this DNA "proof" correctly in that, he uses a 15cm match to prove his line?
Please correct me if I am wrong.
15cms cannot be used in this manner for a connection only two hundred years in the past
Actually, Mark noted in humphrysfamilytree.com/DNA/baronet.html that such matches are common for such relationships.
In addition, in the previous page I linked to, he explains how such matches didn't happen with the Letitia Blennerhassett of Tarbert theory.
The problem is not the 15 cM, the problem is the lack of triangulation.
What the first DNA test actually proves is that Meg Niemi is related to John Chute. The DNA test itself does not show how they are related - if they are (as claimed) fifth cousins once removed, then any one of Meg's 64 sets of 5-great-grandparents could be the same as one of John's 32 sets of 4-great-grandparents (a total of a bit more than 2,000 possible relationship paths). Do you know all of the ancestors of Meg and all of the ancestors of John back to the late 1700s well enough to be able to rule out any relationship other than through the Cashels and Blennerhassetts?
As Wikitree (yes, Wikitree) explains (at https://www.wikitree.com/wiki/Help:Triangulation), once you are beyond third cousins, you need triangulation before you can consider a relationship proven by DNA. That is, you need to see the same piece of DNA in two or more matches in order to establish the branch through which that piece of DNA has descended.
The match between Meg Niemi and John Chute is on GEDMatch, so we know the exact piece of DNA on which they match (on Chromosome 11). In order to prove that this match is because the Cashels are descended from the Blennerhassetts, you need another descendant of George Cashel (through a child other than the ancestor of Meg Niemi) who also matches on at least 7 cM of that segment on Chromosome 11, and you need another descendant of Rowland Blennerhassett (through a child other than the ancestor of John Chute) who matches on at least 7 cM of that segment.
Mark Humphrys offers some other DNA matches between Derval McGrath, Nuala Duggan, and "Bayly 10"; however, these tests are on ancestry.com (rather than GEDMatch) and thus do not give any segment information - in other words, for purposes of triangulation they are worthless. If he can persuade those test takers to export their ancestry.com results to GEDMatch, and then can show that the matches are also on that segment of Chromosome 11 - then he will have proven his claim. But as it is, the relationship between the McGraths and the Yieldings might be through a completely different patch than the relationship between Meg Niemi and John Chute.
Thus, despite what Mark claims, the relationship has not yet been proven - we know that Meg Niemi and John Chute are related, but the DNA has not yet proven that George Cashel and Rowland Blennerhassett are related.
--Carl-Henry
Occam's razor applies. There's no reason to complicate matters by supposing undocumented connections.
The Cashels used Blennerhassett as a middle and even first name and had a tradition of being descended from the Blennerhassetts.
In addition, Thomas Blennerhassett of Gortatlea said that George Cashel's mother must have been daughter of Sir Rowland Blennerhassett.
"There is no doubt that the Cashels and their descendants used Blennerhassett as a given name and a middle name. But that doesn't mean that they were necessarily descended from that family. It's at least equally possible that George "Blennerhassett" Cashel assumed the the name as a gesture of respect for "A. Blennerhassett" who recommended him for the RIC. (BTW only a single record is given indicating that George Cashel actually used the Blennerhassett name throughout his long life. See if you can find it.. :-) )"
I hope you can now accept the fact that DNA testing has NOT yet proved this descent. And nobody has even suggested "supposing undocumented connections", to use your phrase above. A "family tradition" is just that, a tradition - not evidence at all of an actual biological connection.
As I told you back in April, "it pays to maintain a healthy dose of skepticism in cases like this". You seem to lost any sense of skepticism in your rush to accept this as a proven descent. That's not Occam's razor - it's simply bad judgment.
Thing is, two of the three candidates for Arthur Blennerhassett, J.P. were members of the Baronets branch. Now, DNA has shown a descendant of George Cashel to be related to a descendant of the 1st Blennerhassett Baronets, best explained by George Cashel's mother being a daughter of Sir Rowland Blennerhassett. That doesn't look like a coincidence to me. (BTW, I think Arthur Blennerhassett, J.P. was the future 3rd Baronet. He married a Catholic and converted to Catholicism. He may very well have had sympathy for a disowned Catholic cousin.
Mark Humphrys
2020-06-20 13:26:41 UTC
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Thanks Carl-Henry. I am delighted someone more knowledgeable than me about DNA is having a look at my Blennerhassett DNA project. Please don't go away.
Well first of all I am delighted Paulo is interested. I did not know he had a post here until today.

It is indeed an interesting hunt. So let me explain. As Paulo said, I spent a lot of time on a "Plan A" theory, namely that my family descends from Letitia Blennerhassett of Tarbert (born 1780). I did no less than 295 one-to-one DNA comparisons on Gedmatch and the best I got of all of them was 8.4 cM. And there was no pattern either.
So I finally dumped Plan A and tried to find a Plan B theory.

The obvious Plan B theory was the Baronets branch, since there was some evidence we are connected to their seat, Churchtown House, Co.Kerry, plus some other clues, explained here:
https://humphrysfamilytree.com/Blennerhassett/proof.html

Then on my very first Baronets sample, I got a 15 cM match with a George Cashel descendant.
The Baronets line person (Chute) is in the UK. Known ancestry is heavily Anglo-Irish Munster:
https://humphrysfamilytree.com/Blennerhassett/francis.chute.html
The Cashel person (Niemi) is in the US. Known ancestry is mostly Scandinavian and Russian. The only Irish Munster line is Cashel (ancestors born 1807 and 1840). There is one line to Co.Derry (Porter, ancestor born 1752).
https://www.ancestry.co.uk/family-tree/tree/152470640
Niemi could hardly be less likely, of all the people in my tree, to match Chute.

So you can see why it looks good to me.
There are then further 9 cM matches to the Baronet's wife's family, and this combined with the clues in the documents.
And then last week, I discovered the baptism of a daughter of Sir Rowland, previously unknown to any of the printed histories.
The baptism of Melisent Blennerhassett in 1768 is here:
https://churchrecords.irishgenealogy.ie/churchrecords/details/56df180183729
When the RCB library re-opens, I will go there and photograph the original.

So I think I'm getting somewhere.
However, I like your scepticism, so I need to keep going.
On triangulation, no luck so far.
I have 11 George Cashel descendants on Gedmatch.
None of the other 10 have a matching segment (over 3 cM) in that region on Chromosome 11 that Niemi matches.

In reply to the other issues, no, I only have DNA of a single descendant of Sir Rowland so far. I am working on more.
And then on the Bayly matches, yes that person is only on Ancestry. I am trying to get them onto Gedmatch.

I tried using Gedmatch Triangulation tool but it never seems to terminate.
Is there anything else I could do with the material I have right now?

Carl-Henry, if you drop me an email I could send you the Gedmatch kit IDs and maybe you could have a look yourself?
https://humphrysfamilytree.com/howtomailme.html
Mark
Carl-Henry Geschwind
2020-06-20 17:16:15 UTC
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Post by Mark Humphrys
Thanks Carl-Henry. I am delighted someone more knowledgeable than me about DNA is having a look at my Blennerhassett DNA project. Please don't go away.
Delighted to see your post, and that you are eager to work on solidifying your proof.
Post by Mark Humphrys
It is indeed an interesting hunt. So let me explain. As Paulo said, I spent a lot of time on a "Plan A" theory, namely that my family descends from Letitia Blennerhassett of Tarbert (born 1780). I did no less than 295 one-to-one DNA comparisons on Gedmatch and the best I got of all of them was 8.4 cM. And there was no pattern either.
So I finally dumped Plan A and tried to find a Plan B theory.
https://humphrysfamilytree.com/Blennerhassett/proof.html
Then on my very first Baronets sample, I got a 15 cM match with a George Cashel descendant.
https://humphrysfamilytree.com/Blennerhassett/francis.chute.html
The Cashel person (Niemi) is in the US. Known ancestry is mostly Scandinavian and Russian. The only Irish Munster line is Cashel (ancestors born 1807 and 1840). There is one line to Co.Derry (Porter, ancestor born 1752).
https://www.ancestry.co.uk/family-tree/tree/152470640
Niemi could hardly be less likely, of all the people in my tree, to match Chute.
Very glad to see the Niemi tree. Yes, the Cashel connection looks most likely, though the next obvious place to look would be whether John Chute might have another ancestor in Munster who intermarried with the Cashels or an ancestor in or near Co. Derry who might have intermarried with the Porters (at least the data you've linked to for the Chutes gives only a sliver of John Chute's family tree, so it is difficult to tell what else might be lurking there). But then, given that the Cashels seem to have been very adventurous (George's son went to Alaska and had a kid with an Aleut woman!), one also wonders whether perhaps one of John Chute's 18th-century ancestors was equally adventurous and sowed his oats in Finland or Denmark.
Post by Mark Humphrys
So you can see why it looks good to me.
There are then further 9 cM matches to the Baronet's wife's family, and this combined with the clues in the documents.
And then last week, I discovered the baptism of a daughter of Sir Rowland, previously unknown to any of the printed histories.
https://churchrecords.irishgenealogy.ie/churchrecords/details/56df180183729
When the RCB library re-opens, I will go there and photograph the original.
So I think I'm getting somewhere.
However, I like your scepticism, so I need to keep going.
On triangulation, no luck so far.
I have 11 George Cashel descendants on Gedmatch.
None of the other 10 have a matching segment (over 3 cM) in that region on Chromosome 11 that Niemi matches.
In reply to the other issues, no, I only have DNA of a single descendant of Sir Rowland so far. I am working on more.
And then on the Bayly matches, yes that person is only on Ancestry. I am trying to get them onto Gedmatch.
I tried using Gedmatch Triangulation tool but it never seems to terminate.
Is there anything else I could do with the material I have right now?
I have to admit that I have not actually used the Gedmatch triangulation tool (too cheap to pay for the subscription). However, I see that, when I plug the two Gedmatch IDs into Gedmatch's "People who match both, or 1 of 2 kits" tool, I get 160 hits for people who match both Meg Niemi and John Chute with at least 7cM (though not necessarily on the same segment). Of course, on Gedmatch you generally don't get a family tree or other helpful hints, but only a cryptic user name to identify the match, but perhaps you are sufficiently familiar with the genealogies to be able to figure out at least some of these mutual matches. The strategy to use here is the one outlined by Joe C in post #9 above - do the mutual matches cluster on Meg's Cashel line, so that you can have assurance that the match with John is on this line?

Another alternative would be to persuade either Meg to do a test at 23andMe and/or John to do a test at Ancestry, so that you can then look at mutual matches in the 23andMe and/or Ancestry databases (which may be a lot more user-friendly than the GedMatch database).

I take it (since you do not mention it in your discussion) that Meg does not have any matches with the Yielding descendants at Ancestry (if there were such a match it would be very nice, because that would be a good indicator that Meg's match with John Chute is through John's Blennerhassett/Yielding ancestors rather than some other part of his ancestry).
wjhonson
2020-06-20 19:58:42 UTC
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I have many relatives named such things as George Washington Smith and Andrew Jackson Collier. That is exactly *zero* evidence that they are related to George Washington or Andrew Jackson.

That a family lived in an area where the local birthing doctor was named Miles Davis, means lots of children named Miles Davis Jones, and Miles Davis Taylor. Again zero evidence of any blood relation.

Checking with a 13cm cutoff I have 36,000 apparent eighth cousins. Clearly this is a fallacious argument.

As a dedicated DNA-sleuth myself, you really need to show, generation by generation, that this particular specific segment descended *only* along that specific line to yourself, and to your matches.

Just finding *some* segment you share with some eighth cousin, is not sufficient.
c***@gmail.com
2020-06-20 21:35:27 UTC
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One other point.

A DNA match of 17 cm. does suggest the possibility of say a 5th cousin kinship between two parties. However, in my own DNA results, there is a person who matches me at 8 cm. who descends from a brother of my great grandfather. Given our common ancestry, he should be at least 30 or 40 cm. He is not.

There is also a woman who descends from a sister of my 2nd great grandmother. She matches neither me or my brother. She does, however, match all of our common relatives. Reviewing all of her own DNA matches and comparing them to my DNA matches, it is abundantly clear that we are members of the same family.

Even though I do not match this woman, I do have 90,000 other DNA matches.

Short end of the stick: One DNA match at 17 cm. means nothing. Such a match might be a clue to common kinship, but that is all. Far more testing and common matches are needed.

DR
Paulo Ricardo Canedo
2020-06-20 22:17:21 UTC
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Post by wjhonson
I have many relatives named such things as George Washington Smith and Andrew Jackson Collier. That is exactly *zero* evidence that they are related to George Washington or Andrew Jackson.
That a family lived in an area where the local birthing doctor was named Miles Davis, means lots of children named Miles Davis Jones, and Miles Davis Taylor. Again zero evidence of any blood relation.
Checking with a 13cm cutoff I have 36,000 apparent eighth cousins. Clearly this is a fallacious argument.
As a dedicated DNA-sleuth myself, you really need to show, generation by generation, that this particular specific segment descended *only* along that specific line to yourself, and to your matches.
Just finding *some* segment you share with some eighth cousin, is not sufficient.
Your comparisons don't really work, as Blennerhassett is a much rarer surname than those. In addition, the Cashels, actually, had a tradition of being descended from the Blennerhassetts. Then, DNA showed a Cashel descendant to be related to a Blennerhassett descendant. The chances of this being a coincidence are pretty small.
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