Can autosomal DNA confirm parents of Puritan Great Migration ancestors? (As in Confirmed by DNA Status)

+4 votes


I'm reviewing the DNA related suggestions for the Puritan Great Migration Project, and trying to get a handle on the standards for the "DNA Confirmed Status".

I understand that the suggestion is triggered by the lack of a DNA confirmation statement.  But I'm wondering if autosomal DNA would ever be able to confirm a parental relationship that far back (born 1620 or earlier)?  Perhaps there could be some DNA, maybe a sticky segment, that's triangulated, that may support a connection in a vague way???  My understanding is that any relationship that far back cannot be confirmed through autosomal DNA.  

I'm thinking that if its the case that atDNA can't confirm the relationship, then it would be better to state that up front, rather than ask for a confirmation statement that's not valid anyway.

[Updated to include DNA Confirmation Tag 7.20.20]

in Policy and Style by M Cole G2G6 Mach 3 (39.7k points)
edited by M Cole
Another question popping up as I'm trying to understand the requirements for the DNA confirmed status.  For Y-DNA, do both matches need to be on WikiTree?

3 Answers

+6 votes
No sorry. Autosomal DNA is only accurate going back about 6-8 generations or about 200 years at the most.

If you are male, you could possibly do a yDNA test and see if the name goes all the way back - but that is about all I could suggest. If you are not male then perhaps you can ask a brother, father, paternal uncle or a male first cousin on your fathers side to do a yDNA test.
by Robynne Lozier G2G6 Pilot (939k points)
I'm not personally looking to confirm...actually questioning whether we can/should be using the status for PGM profiles.

In the help section it distinguishes between DNA supported and DNA confirmed....even with Y-DNA, I'd be more comfortable with "DNA Supported."
+6 votes
No, it is not possible to "confirm" a relationship that far back.  The noise exceeds the statistics, and even if there is a suggestion of support, it cannot be backed with confidence by statistics.  In a few rare cases of apparent autosomal support, the explanation is usually endogamy:  people marrying close relatives.
by Michael Schell G2G6 Mach 3 (35.0k points)
+3 votes
Just a follow up on Robynne and Michael, atDNA will, indeed, only go back 6 to 8 (pretty much max) generations.

One activity I have done is to have my mtDNA and my brother's Y-700 DNA done at FTDNA. I have also joined 'groups' on FTDNA to learn more about what we can and cannot determine with DNA. I've also taken a genetic genealogy (GG) course through our local historical society and a full day workshop with Blaine Bettinger earlier this year (pre Covid19). I am still learning!

One of the FTDNA groups that I joined was the Baldwin surname study. A wonderful man, Donn Devine, JD, CG was manager for this surname study because his wife was a Pennsylvania Baldwin descendant. Donn died a year ago at 94 years and I am glad I kept his emails to me. He listed my brother with the CT Baldwins. Following the GG course, I spoke with the instructors and when Covid slows down (and it will someday) we are going to write a 'proof' on the 10 or so lines that I received from Donn to trace back to the 'common ancestor.' This is not a sure fire way to confirm. This Y DNA will assist with tracing back to the common ancestor via these various Y DNA lines; however, it is ONLY good for this particular Baldwin line and not other male grandparents.

Again, classes have helped a great deal to understand atDNA, mtDNA, X, Y as to their strengths and weaknesses.
by Carol Baldwin G2G6 Pilot (521k points)
Can I slip in a related question on atDNA here?  Suppose you have an indication from autosomal that, say, you have common greatgrandparents with a expected/suspected cousin.  Because autosomal is not gender-specific, presumably it is not safe to say that both greatgrandparents are equally 'confirmed'.  It would seem it is only indicating that "Either One or Both" are your joint ancestors, so you cannot put a definite parental DNA match from your grandparents up to both ggparents, and there is not a box you can tick to say 'either or both'.  Although you can record matches at yours and your parents' level.  Am I right?
There are others on this site who can answer your question with more eloquently, but my understanding is that you can usually know whether you are related to both or just one of your great-grandparents by looking at the amount of shared DNA.  Using the chart created by Blaine Bettinger's Shared DNA Project, the average amount of DNA you would inherit from both ggrandparents is 887 cM, while if it is just one of them, the amount would be about half that.  Of course, the actual amount shared varies for each case, so there might be some cases where you could be fooled by a lower number (say, if you shared only 650 cM).  You could also be fooled if, say, your ggrandfather had a child with the sister of your proposed ggrandmother.  Beyond that, if you can identify other separate individuals who you share DNA with who share DNA with only one or the other ggparent, then almost certainly you got your matching DNA from both of your ggparents.

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