Five years have elapsed since David Christian undertook Ancestry.com DNA testing in early 2017. David had been seeking matches on his Dering Mathew Byam Knollys Carey lines along with lines such as his Tiearney line. Over that time, David’s sister, Barbara, had also undertaken Ancestry.com DNA testing. An overseas Ancestry.com DNA match was identified in 2019 (9 cms on Dering line) and another in 2020 (15.3 cms on the Dering Twisden line using the Gedmatch Tier 1 Tool), along with many Ancestry.com DNA matches with other Australian descendants of Daniel Dering Mathew.
A pedigree family tree for David’s and Barbara’s mother Eunice Adele Christian nee Green linking back through Daniel Dering Mathew is shown below:
By 2022, the test pool of possible Ancestry.com DNA matches with other Dering Byam Mathew Knollys Carey descendants beyond Australia, had continued to grow since 2019-2020. Back in 2020, it was considered that it would be interesting to see if any other such closer matches emerged in the future?
Now in 2022, there are 13 more matches with Dering Twisden Byam and/or Knollys Carey descendants, and with another 9 matches with Mathew descendants with heritage from either Cornwall or Wales – as follows.
- In 2022 David and Barbara each had a futher Ancestry.com DNA match with two other Twisden descendants, of 8 and 9 cms respectively,
- Also in 2022, eight American matches of 7 and 8cms were identified for David and Barbara with descendants of Henry Byam, brother of David’s and Barbara’s ancestor Edward Byam, father of William Byam who married Boleyn Carey descendant Dorothy Knollys,
- Additionally in 2022, three matches of 6, 7 and 9cms were identified for David with other Carey Knollys descendants, and
- There are also potentially up to 9 Ancestry.com DNA matches with David and Barbara and descendants of Mathew family members – 3 with heritage from Cornwall and Wales on the Llandaff and Radyr lines, including the Radyr – Thules Tipperary lines. Many of these are via the USA, with their Mathew ancestors emigrating to Virginia, Maryland and Pennsylvania in the USA during the Colonial American era – so mostly these are quite distant going back over centuries – further back then the respective DNA matches for the Byam and Dering lines.
These matches again raise the potential for Endogamy being at play, especially as so many of these new matches by 2022 have North American Early Colonial Ancestry:
As noted in 2020, matches with MRCA’s (Most Recent Common Ancestors) being so far back was quite a surprise. FamilyTreeDNA has a table of expected cms for DNA matches for different degrees of cousins. Could it be a case of IBC (Identical by Chance) rather than IBD (Identical by Descent), and so be dismissed? Or could it be a case of Endogamy, ie pedigree collapse, given the very well known degree of intermarriages across the various Plantagenet ancestral lines of Daniel Dering Mathew, David’s 4 x great grandfather? That intermarrying across about eight generations and some centuries of Plantagenet descendants from John 1 Plantagenet could certainly account for a fair degree of Endogamy. This has been well documented on various internet sites across the web.
In researching my own Brown Sherwood Ford Shove ancestry in Early Colonial American times from 1623 in New England and c.1611-1613 Virginia, I have observed similar unexpectedly close matches. I have raised this in various DNA groups and I was informed that Endogamy was known on the North East coast of the USA, and not confined to the better known examples of the Jewish Ashkenazi and Acadian populations.
Impact of Endogamy Notes :
Normally there can be a degree of confidence down to matches of 10 cms involving 5th – 8th cousins, especially where the matches also have family trees which point to MRCA’s Most Recent Common Ancestors. So it would be interesting to learn of the degree of confidence in matches of around 10 cms where they involve matches more distant than 8th cousins and where a fair degree of intermarrying has occurred over generations over centuries, ie potentially Endogamous situations. At this stage I haven’t found too much information to answer this question. I have raised the issue of Endogamy in possible DNA matches of Plantagenet descendants in another forum. At this stage, mostly the responses were not so much science evidence based but rather opinions being expressed.
Perhaps in time, there may be more information available?
References on Endogamy
Daniel Dering Mathew - A Family History 