I hope the following helps in illuminating my thoughts on the use of DNA and what I think needs to be done. I use my own line as construct to give you a view of the process.
Yes I knew that George's ancestor was William. However, his dates differ ie, 1754 as opposed to 1757 if I recall and I thought that we would easily get to the next step with this but it seems like it is a massive first step beyond the George.
Here is what we do know: The DNA does not match the larger group of PW County Calverts and Colberts. It does not match my line of Calverts out of Western and Central PA.
This is the second reason that we need at least another particpant of this ancestry right off the bat. It would be good to get an adjacent line to George's as far back as we can go. With my PA line, we have a similar problem:
We need more records and a better triangulation of descendants with DNA to build the case that John Calvert of Mifflin(Centre) is the brother of Isaac Calvert, and something that more firmly identifies both as sons of Thomas Calvert b 1716 son of Joshua Calvert who married Deborah Harlan. This seems to be getting clearer and clearer as we go but a lot more work needs to be done. We can clearly identify Isaac Calvert of Chester(The only Isaac essentially around who must be the known son of Thomas Calvert b 1716. We can build a strong case for this Isaac to 1790 Census.
Conversely, We have proved Isaac Calvert of my line in Greene Co beginning before 1798(Tax record). So we have a gap to work with, 1791-1797 and need something, anything, to show that Isaac of Chester is the Isaac of GreeneCounty.
In the process we are working to demo that JOhn Calvert of Mifflin, Isaac Calvert(Jim Ray via Kent descends from Robert& I descend from Thomas, Robert's brother). We now have 5 samples but we really need Ezekiel, John Calvert 1777, Francis 1780, William 1791 and Isaac Jr as it will prove scientifically direct common ancestor for all since there is no document for the early children of Isaac that shows a direct relationship as father and son(yet). More than this: Job Calvert apparently had no male sons that survived( I am speculating this). But John Calvert 1766 in family stories is said to have had eight siblings. A lot of work to do.
Jacob Calvert has two descendants who match the 3 for Isaac and they descend from John of Mifflin also But there is more to do from that side as well. John Calvert 1766 m Hetty Jones. We have no male descendant from this line at all, though John was most assuredly the son of John of Mifflin though proven only through family stories and adjacentness in Mifflin(Centre) via Tax lists and Census.
Hence you can see the pattern I am working on for male siblings of JOhn of Mifflin, and descendants of different lines.
I would suggest the same is true for William Calvert who married Elizabeth Nod(d)ing.
I do know descendants also from William but thus far they have declined to participate.
We also have Calverts of Frederick CO VA, those who are tied directly to John Calvert of Ireland. None have stepped forward with a male descendant to participate in the project.
I would suggest at this time your focus should be contacting other male descendants(any of them) from William but also working with other Calverts who identify themselves as descendants from Ireland Chester Co or not, quaker Calverts or not. I am focused on this as well. Marilyn has one line finally participating-Larry Calvert. David Calvert just joined---he is descended from an Obediah Calvert. I am sure that it is not the son of George of Deephole farm but rather either John Obed of JOhn 1692 or Obed of George Calvert 1694. I am awaiting Clarification on this.
Julia who has joined in the question is married to the son of a Calvert. One of the Uncles will participate(I believe) and that this line descends from George Jr and Obed, not John Calvert 1692...so that is a gain in two different Calvert descendants both of the Prince WIlliam Co(Stafford Co) VA families. Thus they are of George of 1668 until we figure someone out for Richard Calvert's line(b1669) son of WIlliam PSOM b 1642/3.
As I have speculated, the line in East SHore MD is descended from William PSOM son, William b 1666. I have not proved this but my logic is at least well found. We do have Colberts who are in the group of participants who descend from William Calvert m Bridgett Howard(I think that is her surname) and I think this William is the grandson of Alexander Calvert and Mary Wheeler of Somerset Co MD. It could possibly be the son WIlliam b 1745/6, but there are the following Males: Isaac, William, Levin, Michael, and one more that I can't recall of top of my head.
If I am wrong about this this line will either be Presybterian/Scot/Welsh or another line of the Irish Calverts. But we have nothing to cross-verify even the WIlliam and Bridgett descendants yet.