Sourcing a trace of African DNA

Modern developments in genetics have made it possible for anyone, at moderate cost, to have their DNA sequenced, and this has had exciting consequences. DNA can identify family members, and also give a broad idea about where on the planet our ancestors may have come from. Rob was the first in our extended family to discover an unexpected trace of African heritage in his DNA, identified through Ancestry.com. Browsing through DNA readings of individuals listed on Ancestry shows that such a trace is rare amongst Europeans and Australians of European descent. 

Where does the African trace come from?

To find out which of his relatives also had an African trace, Rob encouraged his various family members – close and distant – to also have their DNA tested. He discovered many of them shared the African trace. 

To find out where this small but real African fraction came from, Rob developed a table where he listed the ethnicity findings for the various branches of his family. Some had used Ancestry for their DNA testing, some had used My Heritage. 

Family history research had already identified a couple called Andrew and Isabelle Munro (nee Jennings) who were the great grandparents of me and my sister Chris. Andrew and Isabelle are also the great grandparents of Rob and are the most recent ancestors shared by the three of us. Thanks to family history research undertaken by a number of her descendants (including Rob, Sandra and Christine), considerable information about this couple has come to light, including approximate years of birth of their children, their children’s names, and Andrew’s work history with the British East India Company.

Over time, as more family members had their DNA tested and were included in Rob’s table, the inheritance pattern crystallised. The African trace was only found in those who were descended from Andrew Munro and Isabelle Jennings. The trace of DNA for this branch of the family was typically 1% to 3% in our generation, though there were a couple who had no African trace, including Sandra (for a discussion on causes of variability in these percentages see further on). Family members who were a generation closer to Andrew and Isabelle had about 5% to 6%. Ancestry.com further identified the African DNA as Bantu. Some cousins in Rob’s generation (which included Sandra and Christine) who were descended from Andrew and Isabelle also showed around 1% Southern and Eastern Indian, and this fraction was usually less than the African fraction. 

To put it another way, the table showed that either Andrew or Isabelle (or, unlikely, both) must have had some African ancestry and a smaller proportion of Indian ancestry.

Andrew or Isabelle?

The next question to be considered is whether Andrew or Isabelle was part African. 

Because the amount of African DNA increases each generation closer to Andrew and Isabelle, we can work back from our own African fraction and calculate that Andrew or Isabelle must have had at least 25% African DNA. This means that if we could meet them, we would easily be able to tell which of them was part African. Fortunately, we have evidence that tells us something about what they looked like.

The above portrait of Andrew Munro has come down to us via his daughter Blanche Munro. Rob has scanned and shared it. According to Andrew Munro’s enlistment record, he had grey eyes and brown hair and was born in Scotland.

This is a photo of Isabelle, taken in her middle age when she was living in Australia. Her skin is darker than most Australians, her hair is frizzy, and her eyes are brown. She was born in India at a time when there was a sizable African community there, including the Siddi, an ethnic group whose members are descended from the Bantu peoples of Africa.

Isabelle herself claimed her family were Armenian Parsis, but these DNA results contradict her claim, showing instead a largely African heritage

It is safe to assume from these portraits that it is Isabelle, not Andrew, who has African ancestry. This is fortunate because at the time of writing very little is known about Andrew Munro’s family of origin other than the probable name of his mother, making it difficult to use DNA evidence to find out more about them. 

George or Catherine?

After Rob had established Isabelle’s African inheritance (with some Indian as well), the next step was to find out whether that inheritance came from her father or mother. To do that, traditional family history research would be essential for matching DNA findings to specific ancestors.

Research has shown that Isabelle’s father was George Jennings, born in about 1803 in England.[i] According to George’s marriage certificate his wife’s name was Catherine Jacob, but at the time of writing we know little about Catherine beyond the fact that her name also appears on Isabelle’s baptismal record.

Either George Jennings or Catherine Jacob (or, unlikely, both) had African ancestry, and the amount of their African ancestry would have been somewhere in the range of 40% to 100%[ii] . Fortunately, both are close enough to our own time that it is possible to use DNA links to establish which one was part-African”[iii]

Investigation of DNA connections

Because more is known about George Jennings than his wife Catherine, Rob started his investigations with his ancestor (and Sandra and Christine’s ancestor) George. He needed to find cousins who were descended from George’s family but not from Catherine. In other words, he was looking for descendants of his ancestor George Jennings’ siblings, aunts, or uncles to find out something about George Jennings: whether there was an African trace in his family.

Rob searched the Ancestry website for living individuals who had genealogical connections with us going back 6-8 generations, eliminating anyone whose closer genetic connection with us meant that they could have been descended from his wife Catherine. Only a fraction of these distantly related individuals would be the ones Rob was looking for: descendants of a member of George Jennings’ family. For Rob to identify them, it was necessary that they had made their family tree available, and that they had done enough family history research to establish their connection with a George Jennings.

Rob was able to find 30 individuals who met these requirements. Each of these individuals had a George Jennings who belonged to the family of a George Jennings (born 1803) and Ann Packer, from Sittingbourne.

The linkages of descendants in the Jennings family

Thirty living individuals are connected with us at the level of 4^th, 5^th, or 6^th cousins and are descended Ann Packer and George Jennings, or from Ann Packer’s parents, Stephen Packer and Sarah Horton. By looking at the family trees they had provided, Rob was able to draw up a combined tree that showed how each one was connected to our George Jennings.

In the figure below, our 5^th great grandparents, Sarah Horton and Stephen Packer, are shown on the left. Their children are Thomas, Stephen, Francis, and Ann Packer. Ann Packer married George Jennings, and their children are Sarah, John, Mary, George, and Ann Packer. Ann Packer married George Jennings, and they became the parents of our George Jennings, born 1804.

The descendants of Sarah Horton and Stephen Packer (as located at July 2020)

It can be seen from this figure that 8 of our distant relatives located by Rob are descended from Ann Packer’s parents, Stephen Packer and Sarah Horton, but not directly from Ann Packer. These are descendants of Ann Packer’s siblings. Four are descended from her brother Thomas Packer, 2 from her brother Stephen Packer, and 2 from her sister Frances Packer. 

Twenty-two of these 30 distant relatives were direct descendants of Ann Packer and George Jennings. They were all descended from their daughter, Sarah Ann Jennings. Thirteen were descended from Sarah’s son Alfred Swinyard, 6 were descended from Sarah’s son Samuel Swinyard, and 3 were descended from Sarah’s daughter Louisa Swinyard.

None of these 30 distant relatives have an African or Indian fraction in their DNA.

Catherine Jacob

Of all our distant cousins descended from Stephen Packer and Sarah Horton, only those descended from our George Jennings show an African or Indian fraction in their DNA. This confirms that although George Jennings’ children had African heritage, George himself did not.

Some might argue that perhaps George did not really have the same parents as his siblings (that is, he was the son of the milkman, or some other scenario). If this were the case, the sibling link between George and Sarah would not be as firm as it is. The fact that George was a middle child, not the first or last, further refutes such a claim, as does George’s military records, which place him in units of soldiers with European ancestry.

Catherine Jacob and some or all of her ancestors was the source of our trace of African DNA.

A note on African fraction estimates by Ancestry and My Heritage

As a rough estimate, Catherine would have had between 40% and 100% African ancestry. She probably also had some South Indian and West Asian ancestry.

The set of DNA markers that Ancestry uses to define African ancestry will be roughly halved each generation down. Let’s say Catherine had 100% African ancestry (remembering that it could have been her parent). Her children would have inherited about 50% of her African DNA markers, but not exactly 50%, because the process of inheritance is random. Her grandchildren would have inherited on average about 25%, but some would have more and some less than that. Because we are 5 generations down from Catherine the fraction of her DNA in our cells is small, and variable. That is why we find that some individuals in our generation have a higher African fraction (like Rob, who has 3%) while others have hardly any at all (like Sandra, 0%). Those (like Sandra) who have no measurable African heritage still carry a smattering of Catherine’s genes, but not the ones that define African-ness for the testing company.

Another cause of variation in the amount of African DNA found in our generation of Isabelle’s descendants is the testing company. Ancestry has tended to give a higher African percentages than has My Heritage. Both those who have used My Heritage for their DNA test were found to have 0% African markers (Sandra and Helen Normoyle). 

WikiTree Link Isabella (Jennings) Munro (1837 - 1938) Family search Tree : Isabella Jennings (26 December 1836 – 11 November 1938)

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The URL for this post is: hhttps://ancestralresearchjournal.blogspot.com/2022/03/sourcing-trace-of-african-dna.html originally published 23 March 2022

Written 2020 Authors Sandra Williamson & Chris Filiamundi in collaboration with Rob Snow

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[i] Ancestry.com. England, United Grand Lodge of England Freemason Membership Registers, 1751-1921 [database on-line]. Provo, UT, USA: Ancestry.com Operations, Inc., 2015. Membership 15th unnumbered entry on page 802  in the United Grand Lodge of England Freemason Membership Registers  for Lodge of Hope, Ahmednuger for George Jennings who joined on 2 February 1835 at the age of 32; Original data: Membership registers 1751-1921 from the collection of the United Grand Lodge of England held by the Library and Museum of Freemasonry. Images reproduced by courtesy of the Library and Museum of Freemasonry, London. Rights reserved.

[ii] https://familylocket.com/what-do-you-want-to-know-3-steps-to-focus-your-dna-research/

[iii] https://familylocket.com/what-do-you-want-to-know-3-steps-to-focus-your-dna-research/