Month: November 2019

Seeking Triangulation: Anne Sainsbury of north Wiltshire

UPDATE. January, 2022. Y-DNA testing indicates Richard Sainsbury of north Somerset was born in Urchfont, Wiltshire in 1708. Any speculation in this post that suggests otherwise is therefore obsolete. It remains online as a record of this research project.

UPDATE JAN. 30, 2020. Two of the three tests described in this post were uploaded to MyHeritage for detailed analysis. At the same time, however, their family trees were investigated to see if they might share a common ancestor on a “non-Sainsbury” line. That proved to be the case. Their common ancestor was likely Joseph Holbrook, born in Somerset around 1750, died in Chew Stoke, Somerset in 1819. However, the research principles described in this post remain true.


After finding and classifying almost 200 DNA matches among our Somerset Sainsbury cousins to other Sainsbury descendants, our focus can now shift to finding matches who have “triangulated segments” of DNA.

What are triangulated segments?

Triangulated segments are segments that all of the selected DNA Matches share with each other. This capability is important for understanding DNA Matches’ relationships because triangulated segments are more likely to be inherited from a common ancestor

MyHeritage Help Center. https://faq.myheritage.com/en/article/what-are-triangulated-segments-in-the-chromosome-browser-%E2%80%94-one-to-many

In other words, if two Somerset Sainsbury cousins (A and B) and an (apparently) unrelated Sainsbury descendant (C) all share the same segment of DNA, those three people likely inherited the same segment from the same ancestor.

And since we know A, B and C all have a Sainsbury in their family tree, that could be the line on which they share a common ancestor. Looking for and investigating these triangulated matches could solve our mystery:

This simplified family tree shows how two Somerset Sainsbury cousins (A and B) and a triangulated match on an apparently unrelated Sainsbury descendant (C) could point to a common ancestor.

Of the 180 matches we found on Ancestry, only 18 match more than one Somerset Sainsbury cousin, so this is where we can focus our search for those who share triangulated segments of DNA:

Discovering which (if any) of these multiple matches share triangulated segments of DNA would more or less confirm a common ancestor among them. But whether or not that common ancestor was a Sainsbury would still be left to prove through documentation and other DNA evidence.

Nonetheless, it’s the next step we can take with our DNA tests to resolve the mystery of Richard Sainsbury of North Somerset.

Anne Sainsbury (c.1750 – 1824) of north Wiltshire

Anne Sainsbury was the daughter of John and possibly Bridget Sainsbury. She was either not baptised, or her baptimal record has been lost.

However, her father’s name is recorded on her 1779 marriage license bond. Her mother’s name is derived from her 1824 will, in which she states she would like to be buried in the Langley Burrell churchyard, near her parents’ grave.

We know from that parish’s burial register that a Bridget Sainsbury, wife of John, and a resident of Stanton St Quintin, was buried in Langley Burrell in 1795. This is presumably Anne’s mother:

Burial register of Bridget Sainsbury. Langley Burrell, Wiltshire. August 10, 1795. The register indicates she was a resident of Stanton St. Quintin rather than Langley Burrell.

A good starting point

This Chippenham area match from our set of multiple matches is a good case to start with for a couple of reasons:

The descendant of Anne Sainsbury and William Lessiter and one of the two Somerset Sainsbury cousins included in this match have already uploaded their DNA tests to MyHeritage, which is (along with GEDMATCH) has a tool to show exactly which segment(s) of DNA two or more people share:

Example of a triangulated segment of DNA shared by three people. All three likely have a common ancestor.

Another reason to start with this Chippenham-area match goes back to the middle name — Billet or Billett — that our first Somerset Sainsbury ancestor gave one of his sons.

Using this name as a clue to solving our mystery was described in a previous blog post (A Day of Coincidence). In this case, the surname Billet is quite common in north Wiltshire. So if its use as a middle name did derive from a family connection, that family might have lived in the same general area (and at the same time) as Anne Sainsbury and her family.

Next steps

  1. We’re hoping to get all three tests involved in this match uploaded to MyHeritage.
  2. Then we can use the chromosome browser that MyHeritage provides to see if all three share a triangulated segment of DNA.
  3. GEDMATCH is another site that could be used for this comparison if all three tests are uploaded to that site. (This video explains the basis of GEDMATCH. It’s also embedded at the bottom of this post.)
  4. If all three share a triangulated segment, it would be a “green light” to spend more time and effort building our Anne Sainsbury’s family tree to answer these questions:
    1. Did anyone in the earlier generations of her extended family marry anyone named Billet?
    2. Did anyone in the earlier generations of her extended family migrate to north Somerset? (Family members often migrated with others. Perhaps our Richard Sainsbury was accompanied by other family members with other surnames.)
    3. Can we uncover any document, facts or coincidences that could link her Sainsbury family to the Sainsburys of North Somerset?