Author Topic: DNA ethnicity logic check / Unexpected result  (Read 6334 times)

Offline AndyH81

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Re: DNA ethnicity logic check / Unexpected result
« Reply #45 on: Thursday 09 December 21 18:49 GMT (UK) »
So, it looks as though you can rule out your match's maternal grandfather, and (as the most likely contenders) you are left with either her uncle, or one of her great uncles? Or at a pinch, since I don't know the ages of these people, a son of one of the great uncles.

Against which, you would want to consider who was most likely to have visited your town, since it was the grandfather who had connections there, and not his wife's family.

(Of course, I don't know where you live, and whether is somewhere that anyone from Ireland might pop over to on a visit, or a place which makes it much less likely that that would be the case.)

I'm from Cheltenham originally, which has always had a relatively high Irish population and gets a huge amount of Irish tourism each year for the races. Not quite sure why that's the case - but it's true.

Offline AndyH81

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Re: DNA ethnicity logic check / Unexpected result
« Reply #46 on: Thursday 09 December 21 18:50 GMT (UK) »
Hi Andy,

There is a DNA tool called "What Are The Odds?" I don't know if you've tried it...

You can use it to create a tree with various branches & input shared DNA cM values.
It then generates hypotheses as to where your most likely position in the tree is.

https://dnapainter.com/tools/probability

Thank you - I'll go and have a look.

Offline TonyV

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Re: DNA ethnicity logic check / Unexpected result
« Reply #47 on: Monday 13 December 21 20:46 GMT (UK) »
Hi Andy

I've only just seen your original post and it has received a lot of attention from helpful posters here. I see that you seem to have moved to acceptance that your biological dad and the man who brought you up are not the same.

I am acquainted with a similar case where the Ancestry Ethnicity Estimate showed a high percentage Irish background for a man whose previously researched tree showed exclusively English ancestry on both sides. The ethnicity estimate was backed up by the fact that most of his closest matches had original Irish ancestry, so just like yours.

In his case he persuaded a 1st paternal cousin and his own brother to take tests. The cousins's test showed no genetic relationship and the brother's test showed a half-sibling relationship rather than a full sibling relationship as both had believed they were all their lives. So clearly his biological father was not the man he had taken to be throughout his life up to that date or indeed his brother's father.

So while ethnicity estimates are a bit speculative (but their accuracy is improving all the time), in his case, and I suspect in yours too, the DNA proves that the estimate is a pretty good one.

The problems start there and I can well understand how disturbing this discovery might be for you. That nevertheless is a known but seldom acknowledged risk of taking a DNA test.   

Offline AndyH81

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Re: DNA ethnicity logic check / Unexpected result
« Reply #48 on: Monday 13 December 21 22:03 GMT (UK) »
Hello Tony, thank you for the reply.

I'm actually probably not as bothered as I should be. Over the years, for more than one reason, I'd had a few thoughts that I might not be. I don't really look like my dad at all - and yet I do look a LOT like one of my uncles and my grandfather, so go figure.

We're doing a legal paternity test to confirm it either way. I figured another more formal opinion couldn't hurt. I'm honestly not sure what to believe when it comes to that because when I spoke to someone in the lab (because I had a techy question the 'sales' person couldn't answer), they seemed to be of the opinion that mistakes or cross-contamination happens relatively frequently when done via genealogy sites but didn't offer any statistics or insight. I got the sense his opinion was that they just didn't take much care of what they were doing and didn't interpret the results correctly! *shrugs* I found that quite worrying. But I guess that's just one person's opinion, I'm sure he must have had his rationale for thinking that.

The mother of the closest match is doing a DNA test for Christmas, so I am hoping that will offer more insight into the nature of all our relationships as, depending on what her test reveals, that should narrow down other potential fathers significantly.

My sister was going to do a DNA test too; however, I think she is feeling so bad for my father that she doesn't want to upset him more. I'm honestly not sure what his reaction would be if he found out we both (god-forbid!) weren't his. Although I think she is probably quite safe there as she does look like him. So I'm not sure that will happen.

I'd be curious to find out whether or not I have an older half-sibling too (as per the other thread)... although no idea how the hell to find that out!!


Offline TonyV

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Re: DNA ethnicity logic check / Unexpected result
« Reply #49 on: Monday 13 December 21 22:18 GMT (UK) »
Andy

It's good that you are not upset finding out what you've found so far. I'm sure that not everyone in your circumstances is so well-balanced.

I am no expert on DNA analysis but as an amateur genealogist since 2004 I've felt that it is the detective work that comprises much of the fun for me and I've found so many things about my own ancestors that I never imagined when I first started.

DNA tests are only half the picture. To be any use you also need to do the family tree legwork and in this case it means assembling trees for people who are matched to you or to examine any trees they have already prepared (and of course to check them). You need to try to find out who your common ancestors are and work downwards to see who was likely to be in the right place and of the right age to be your likely genetic father. Basic things like remembering that if your match is clearly a 1st cousin, you share grandparents with them, so who are the grandparents? If you are likely to be second cousins you share great grandparents etc.

But you probably know all that. Even so, my basic message is that you have to do the "legwork" to couple it to your DNA matches.

Good luck with it all.
 

Offline Nanna52

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Re: DNA ethnicity logic check / Unexpected result
« Reply #50 on: Tuesday 14 December 21 06:38 GMT (UK) »
I have an unknown biological grandfather.  I knew about it and it is one of the reasons I did my dna.  I now know who my great grandparents are on that line, but they had five sons who were alive at the time of conception and in the general area.  I have accepted that may be as close as I get unless someone from my grandfatherís direct line tests.  I have used dna painter, but it tells me the odds are the same for the five of them.  So now it is a waiting game to see if anything new turns up.
You mention ancestryís supposition, but I have two half first cousins that are 572 and 483 cMs.  (Same grandmother, different grandfather).
I think your sister should do a test.  Letís face it there was a sperm diner (biological father) and a real father who bought you up.  Also imagine his relief if it proves she is his biological daughter.
James -Victoria, Australia originally from Keynsham, Somerset.
Janes - Keynsham and Bristol area.
Heale/Hale - Keynsham, Somerset
Vincent - Illogan/Redruth, Cornwall.  Moved to Sculcoates, Yorkshire; Grass Valley, California; Timaru, New Zealand and Victoria, Australia.
Williams somewhere in Wales - he kept moving
Ellis - Anglesey

Gedmatch A327531

Offline AndyH81

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Re: DNA ethnicity logic check / Unexpected result
« Reply #51 on: Tuesday 14 December 21 20:18 GMT (UK) »
Andy

It's good that you are not upset finding out what you've found so far. I'm sure that not everyone in your circumstances is so well-balanced.

I am no expert on DNA analysis but as an amateur genealogist since 2004 I've felt that it is the detective work that comprises much of the fun for me and I've found so many things about my own ancestors that I never imagined when I first started.

DNA tests are only half the picture. To be any use you also need to do the family tree legwork and in this case it means assembling trees for people who are matched to you or to examine any trees they have already prepared (and of course to check them). You need to try to find out who your common ancestors are and work downwards to see who was likely to be in the right place and of the right age to be your likely genetic father. Basic things like remembering that if your match is clearly a 1st cousin, you share grandparents with them, so who are the grandparents? If you are likely to be second cousins you share great grandparents etc.

But you probably know all that. Even so, my basic message is that you have to do the "legwork" to couple it to your DNA matches.

Good luck with it all.

Well, my mother's side seems all good. Oddly enough, I have DNA matches to people who would be on my father's side but I cannot find links to via my mother. But when both sides of your family come from a relatively small area, then there's a multitude of reasons that could be. Especially if my biological father has family in the same areas too.

If I toss out everything that I thought I knew about my father's side, then I can build a reasonable amount of my closest match's family tree based on the conversations we have had and information I can find online. I can also build very partial parts of the family tree of the people in Ireland, I just cannot find the person who connects the two.

And, obviously, I'm also not 100% certain of the nature of my relationship to this person.

I have the details of the closes matches in a spreadsheet now, including notes on who they are related to - or how I suspect people might be related. I tried the Leeds method as suggested but there is either not enough data to make it work, or I am not fully understanding how it is meant to work.

Offline Carmella

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Re: DNA ethnicity logic check / Unexpected result
« Reply #52 on: Friday 17 December 21 19:20 GMT (UK) »
Hi,

As you've mentioned possible half-siblings I've had a few more ideas...

So as you know, some people test DNA on one site, others on another. Therefore "fishing in all ponds" MIGHT help. (Or it might help in the future as more people test). As you say, you've already tried Ancestry & MyHeri, but there is also FTDNA "FamilyFinder" and LivingDNA where you can upload your autosomal DNA raw data or buy a new test.  23andme also do an autosomal test but you would have to buy a brand new one. (I've not tried this one yet).

If funds allow, there is also Y-DNA testing from FTDNA which would give you a Haplogroup - if you were assigned one which is very common in Ireland then it would look likely that your bio-father's father's father's etc line is from Ireland in the last few hundred years. If you discovered your Haplogroup was, for example,  R-M269 this would be more tricky as it is common in men across the UK, Ireland and Western Europe. (But you can join a Project on FTDNA & the volunteers are very helpful in figuring out results I've found).

Regarding your trying to link 2 families together, could it be that your bio-father was born to a pre-marriage couple and adopted (informally/formally) as a baby?  Perhaps he was brought up by distant family or an unrelated couple (in England?)  If you bio-gt/grandparents then married each other and had more children you would have quite big DNA matches to the later children.... 

As you say your 500+ cM match is also puzzled about the link, perhaps he/she genuinely had no knowledge of your bio-father's existence for whatever reason. That is, until you did a DNA test.

Of course this theory could be completely wrong but you never know where exploring ideas may lead.

Offline AndyH81

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Re: DNA ethnicity logic check / Unexpected result
« Reply #53 on: Tuesday 28 December 21 19:19 GMT (UK) »
It's entirely possible the bio-father was adopted, I know of at least 1 person in that family who was adopted as an infant and doesn't know who his biological parents are. Although I think he might be dead now.

My father and I will know for sure, hopefully by new year's day, whether or not we are related or if there has been a mistake as we both did a legal paternity test the other day which is now being processed. :/