In 2016 my husband Greg and I, hoping to learn more about our family history, had our DNA analysed by AncestryDNA.
All living things are related; you and I are related to bananas, earthworms, and the fish, your cousin, whom you ate for dinner.
We share more and longer segments of DNA with our closer cousins, a fact that can be turned to use in family history research: find someone with whom you share a significantly long string of DNA and that person is your genealogical relative – you can probably work out how you are related.
Cousinship in the great tree of life means a common ancestor: whales and cows are related in this way. The DNA we share, or to be precise, the fact that we share it, provides clues about our relative places in the tree. To focus in a little, our relative places in the tree of our direct forebears and cousins are indicated by the segments of DNA we share. The more DNA I share with someone the more recent our common ancestry.
Last year I wrote about AncestryDNA’s ‘ethnicity estimates’ and ‘genetic communities’. AncestryDNA has two ways of looking at your genetic background: the ethnicity estimate which compares your DNA to a reference group and genetic communities where you are linked with cousins who share DNA from a similar geographic area.
AncestryDNA’s ethnicity estimate is intended to be a measure of a person’s ethnic makeup. Are you partly Inuit? Were your ancestors Tasmanian Aboriginals or Scottish Highlanders? AncestryDNA calculates the estimate using DNA data about people who, it is said “…have long-standing, documented roots in a specific area”. This group of people identified by the company provide a reference group for ethnicity estimates.
Genetic communities, compiled on the basis of shared DNA, are defined as “groups of AncestryDNA members who are most likely connected because they share fairly recent ancestors who came from the same region or culture.”
It is said that a large proportion of people who pay to become members of Ancestry do so in order to discover their ethnic makeup, and presumably many of them are satisfied with what they are told. Ethnicity is a tricky concept, however, and Ancestry’s pitch about ‘long-standing’ (how long?), ‘documented’ (by whom? how?) roots in a specific area (how is the area specified?) sharing ‘fairly recent’ (how recent?) ancestors (which?) in a ‘region’ (of what extent?) or culture (what’s that, for Heaven’s sake?), is a pitch that will strike many people as promoting something largely meaningless. [AncestryDNA explains some of this in their 2019 Whitepaper on ethnicity estimates but you can see for example that they are estimating Aboriginal and Torres Strait Islander ethnicity on the basis of 14 DNA samples only.]
AncestryDNA ethnicity estimates were last updated in August 2019. I wrote about this in an October 2019 post: ‘ethnicity’ DNA: beware of inheritance from daughter to mother.
In late July 2020 AncestryDNA updated its genetic communities calculations, including those for communities associated with European and British settlers in Australia. I have looked again at my family’s place in the ethnicity estimates and genetic communities provided by AncestryDNA.
The updated AncestryDNA genetic communities of my husband Greg and of my father became more specific: no longer vaguely “Southern Australia British Settlers” my father is now part of the group “South Australian European and British Settlers” genetic community and Greg is linked to the “Victoria, Australia, European and British Settlers” genetic community. Our ethnicity estimates have not been updated.
As I type these notes my cat Vinnie is sitting on my desk amusing himself by pressssssssssssssssssing randommmmmmmmm keys. I moved his paws, but now he’s taken to making sarcastic comments, and it’s hard to concentrate.
ME: “Most of Greg’s forebears came to the Colony of Victoria at the time of the gold-rushes and the assignment of this genetic community makes sense. AncestryDNA provides the information that just over 127,000 AncestryDNA members are part of this genetic community.”
VINNIE: “I’d say that the vast majority of his forebears didn’t come to Victoria at all. Most of them saw out their days on the African savannah. I’d call this a genetic community of approximately 50 million. What AncestryDNA ‘provides’ is just gas.”
ME: “A year ago I found my mother was assigned to the South Australian British settler community. The only person who was a member of that community with whom she shared DNA was me. My mother came to Australia as a child and all her forebears for several generations were from Germany. As far as we know no relatives came to Australia before World War 2.”
VINNIE: “In the logic trade that’s called a reductio ad absurdum. AncestryDNA’s methods make the daughter the mother of the mother.”
ME: “This was an anomalous result”.
VINNIE: “Did you get your subscription back?”
ME: “In response to this assignment of genetic communities and while waiting for the update, I removed my results from AncestryDNA by updating my settings and choosing not to see my matches and by not being listed as a match. My strategy seems to have worked. In the latest update my mother is no longer assigned to any Australian genetic community.”
VINNIE: “If I remove myself from the veterinarian’s appointment list I will no longer be assigned to it as a cat and you won’t have to take me for my annual checkup. Great.”
ME: “Ethnicity estimates including the assignment by AncestryDNA to genetic communities need to be treated like any other hint with caution but as a clue to one’s origins”
VINNIE: “It was thought that the One Eyed One Horned Flying Purple People Eater had to be treated with caution too, but he turned out to be harmless. There weren’t any purple people for him to eat. You needn’t be cautious about nonsense.
- AncestryDNA White Papers :
- Ethnicity Estimate 2019 White Paper
- AncestryDNA Matching White Paper Last updated July 15, 2020 – Discovering genetic matches across a massive, expanding genetic database
- Genetic Communities™ White Paper: Predicting fine-scale ancestral origins from the genetic sharing patterns among millions of individuals
- Lee, Lydia Ramsey and Samantha. “Humans Share Almost All of Our DNA with Cats, Cattle and Mice.” The Independent. Independent Digital News and Media, April 6, 2018. https://www.independent.co.uk/news/science/human-dna-share-cats-cattle-mice-same-genetics-code-a8292111.html.