Author Topic: DNA Testing  (Read 903 times)

Offline lydiaann

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DNA Testing
« on: Saturday 24 February 18 16:23 GMT (UK) »
Did anyone listen to 'You and Yours' on Thursday this week (22 Feb, 2018)?  One woman was interviewed as she had written to say that different labs produce different results for the same DNA.  You can hear the interview on-line on the BBC website but, in essence, her complaint was that she was tested at 2 different labs and got very different results from each.  Maybe it's useful so you can link up with people with the same familial strand, but as far as 'ethnic identification' is concerned, it seems to be rather iffy.
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Offline davidft

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Re: DNA Testing
« Reply #1 on: Saturday 24 February 18 16:29 GMT (UK) »
I agree with everything you have written there, and indeed it echoes what many people have written on here in the past. Alas there are still those who believe that DNA results and in particular the 'ethnic identification' are infallible and scientifically 'proven'. oh well .............

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Offline Eric Hatfield

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Re: DNA Testing
« Reply #2 on: Thursday 01 March 18 07:05 GMT (UK) »
I think it depends on what we are comparing. There are four things we might compare:

1. The actual DNA results. These will vary a little because different companies test different parts of the genome and different amounts of the genome, but basically the results will be very similar. We don't usually get to see this data, it is a long file of As, Cs, Gs and Ts which is pretty meaningless to us.

2. How much DNA we have in common with other people who have tested. There may be slightly larger differences here between companies, partly because of the different amount of DNA tested, but also because some companies make up for the fact that they aren't sampling at as many points by (if I understand it correctly) "imputing" data that isn't actually tested, but which is statistically likely. I tested with FTDNA and Ancestry and my results here were very similar, only minor differences.

3. Then there is the prediction of the likely relationship between us and our matches. This varies even more between companies because of the differences in #1 and #2, but also because the different companies use different methods to estimate relationships. There is no "right" and "wrong" here because this is still an evolving science, though it would be interesting to see data on how each company predicts relationships that are known. Overall, I have found FTDNA to get this pretty right in a number of cases I can check, and Ancestry did OK too in the few cases there that I could check.

4. Finally, there are the ethnicity estimates. This is where the variation between companies is likely to be greatest because, again, they all use slightly different algorithms to calculate ethnicity. Again, there is no "right" answer, especially as our ancestors may have come from UK 5 generations ago, but Finland 15 generations ago and Ukraine 100 generations ago (as seems to have been the case with my mtDNA). And of course back 5-10 generations, we might have hundreds of ancestors, and they might come from all over the place, making assessment even harder. Everyone (except maybe Ancestry's TV ads) will tell you ethnicity is reasonably accurate at the continent level, but still not very reliable at the country or regional level.

So we should expect #1 and #2 to be pretty accurate, #3 to vary a little and #4 to vary a lot.

Offline Romilly

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Re: DNA Testing
« Reply #3 on: Thursday 01 March 18 11:49 GMT (UK) »
Did anyone listen to 'You and Yours' on Thursday this week (22 Feb, 2018)?  One woman was interviewed as she had written to say that different labs produce different results for the same DNA.  You can hear the interview on-line on the BBC website but, in essence, her complaint was that she was tested at 2 different labs and got very different results from each.  Maybe it's useful so you can link up with people with the same familial strand, but as far as 'ethnic identification' is concerned, it seems to be rather iffy.

Yes, I heard this and was very interested. It confirmed my thoughts on DNA testing:

http://www.bbc.co.uk/programmes/b09rwt8d

Romilly.
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Offline BushInn1746

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Re: DNA Testing
« Reply #4 on: Thursday 01 March 18 14:17 GMT (UK) »
Hi

One thing - DNA Testing is not a substitute for family history research ...

http://www.rootschat.com/forum/index.php?topic=786838.msg6443596#msg6443596
"George HOOD of Selby" Before 1812?

Born about 1785 (Yorkshire per 1841 Census)

Married Sarah RUSSELL at Selby 1815 newspaper - "both of that place".

Buried in the Quaker Burial Ground at Selby as "Not in Membership" in 1845, aged 60 years.

George HOOD of Selby was refused Membership of the Quakers in 1836.

Elected Overseer of the Poor of Selby in 1838.

Had both known (Selby) and unknown (some not stated 1846) property interests.

Possible (but unknown) links to COOK and/or PEARSON names.

Offline Bobby G

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Re: DNA Testing
« Reply #5 on: Friday 02 March 18 02:48 GMT (UK) »
Folks are all caught up in Ethnicity when its really of no benefit to your research. There is a lot of negativity surrounding this and has more years of advancement to happen before consistency, better accuracy. Now even if it was accurate for everyone, it still offers, for the most part, very little benefit.

When you get your DNA results they are split into 2 parts  - Ethnicity and Matching, its the matching that is useful for your family history research.

Eric has explained this in more detail above.

Hi
One thing - DNA Testing is not a substitute for family history research ...
http://www.rootschat.com/forum/index.php?topic=786838.msg6443596#msg6443596

Its another tool that works in conjunction with your paper research.
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Offline BushInn1746

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Re: DNA Testing
« Reply #6 on: Friday 02 March 18 12:29 GMT (UK) »
Folks are all caught up in Ethnicity when its really of no benefit to your research.

 ...

Hi
One thing - DNA Testing is not a substitute for family history research ...
http://www.rootschat.com/forum/index.php?topic=786838.msg6443596#msg6443596

Its another tool that works in conjunction with your paper research.

Precisely.

http://www.rootschat.com/forum/index.php?topic=758922.msg6100988#msg6100988
"the quality here will be dependant on what effort you and the other people put in on there trees to help find the connections,"

 ----------

I was looking at the Tree and Arms of the female and family, who my family married into, in December 1851.

Their Family have made a panel with Arms, as a photograph is online.

I noted one of the locations of their family was a HALL name, so I looked it up in 19th Century Books and the family who lived at that HALL, wasn't theirs!

According to the England & Wales Census they lived at the  ... Ho. / House, of the same name in the same village.

 -----------

There are even a few Rootschatters on these threads admitting to online tree errors, which they have not yet got around to correcting.

 ----------

DNA Testing might only lead to more confusion, if one of the parties, has not worked backward properly and methodically with actual Official Copy records, actual Registers, Census, Wills and other records, from their earliest known family in their current country.

Mark
"George HOOD of Selby" Before 1812?

Born about 1785 (Yorkshire per 1841 Census)

Married Sarah RUSSELL at Selby 1815 newspaper - "both of that place".

Buried in the Quaker Burial Ground at Selby as "Not in Membership" in 1845, aged 60 years.

George HOOD of Selby was refused Membership of the Quakers in 1836.

Elected Overseer of the Poor of Selby in 1838.

Had both known (Selby) and unknown (some not stated 1846) property interests.

Possible (but unknown) links to COOK and/or PEARSON names.

Offline davidft

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Re: DNA Testing
« Reply #7 on: Friday 02 March 18 12:56 GMT (UK) »
-----------

There are even a few Rootschatters on these threads admitting to online tree errors, which they have not yet got around to correcting.

 ----------

Its a brave (or foolish) rootschatter who states categorically that their tree contains no errors, errors creep in despite our best intentions.

And yes I have an online tree with errors in it, but it is private to stop people copying the errors, although I wonder why when I see trees that have children born to mothers who died several years before the childs birth! (I know where the errors in my tree come from and that is when my family tree software got corrupted. Arghhhhh !)

Offline BushInn1746

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Re: DNA Testing
« Reply #8 on: Friday 02 March 18 15:45 GMT (UK) »

... although I wonder why when I see trees that have children born to mothers who died several years before the childs birth! ...


This is the kind of point I was trying to make.

Mark
"George HOOD of Selby" Before 1812?

Born about 1785 (Yorkshire per 1841 Census)

Married Sarah RUSSELL at Selby 1815 newspaper - "both of that place".

Buried in the Quaker Burial Ground at Selby as "Not in Membership" in 1845, aged 60 years.

George HOOD of Selby was refused Membership of the Quakers in 1836.

Elected Overseer of the Poor of Selby in 1838.

Had both known (Selby) and unknown (some not stated 1846) property interests.

Possible (but unknown) links to COOK and/or PEARSON names.