Family history coincidences

[Eric Hatfield]

I have come across some matches that appeared quite strange to me, but which I now believe are simply coincidences. I'm interested to hear if others have had similar discoveries.

I and my aunt have both had our aDNA tested, as have my wife and her mother. There are no known connections between my wife's family and mine, except for our marriage, and our ancestors all came from different parts of the UK (Scotland and southwest England for my wife, and Ireland and Yorkshire for me). Yet it turns out that a person I'll call A matches both sides of these families, one side within the last 5 generations (according to the DNA match) and the other more distantly.

At first I thought there must be some mistake, but discussion on another thread here has suggested to me that this must be the sort of coincidence that happens from time to time. On my side of the family, the common ancestor with A is likely to be about 5 generations back, when I would have 64 4G grandparents, and on my wife's side, if the MRCA is 8 generations back then there would be potentially (I think) 512 7G grandparents. Those grandparents would have thousands of descendants alive today, and somewhere someone from each line got together to produce A.

You would think that people living far apart in UK would be unlikely to get together, but two things show me this isn't necessarily the case:

• I and A both live in Australia, and when families emigrated to Australia they could end up anywhere and the likelihood of this mixing is much greater than back in UK.
• I have a well documented case in my wife's family tree of a poor 23 year old servant girl from Aberdeenshire ending up as a servant in southern England (Sussex) in 1901 while the rest of the family stayed in Scotland.

There is a further coincidence in my case. My maternal grandmother was adopted and her adoptive parents appear in A's tree. Adoptions could occur back then (1891) when a family member had an "inconvenient" child, but I think this is just another coincidence - I don't think they are biologically related to me and the source of the connection with A, because my aunt isn't related to that grandmother but she also matches A.
 
I'm wondering if others have found similar unlikely results that turned out to be coincidences?

[sugarfizzle]

Eric, I didn't want to be the first person to respond to this thread!  However, since nobody else has, here goes.

I have had a similar experience, though again, as in the related thread, not identical. Just recalled it going through my matches.

My husband and I are from very different roots, me mainly from London and Home Counties, he mainly from Yorkshire and the North.

He is a DNA match with someone who has a private tree, but who has responded to me.
.
He matches her and her maternal aunt through one branch of his family from the Birmingham area, they are 5th and 4th cousins respectively.

She contacted me again after looking at my tree and finding that we had a name in common on her father's side, thinking it likely to be on my husband's line again. However, it was on my maternal line.

A married B. After A's death, B went on to marry my maternal 3x great uncle (brother of my 2G grandmother) in London.

There were children from both marriages, who are obviously genetically related to each other, but not to me, though we could have easily ended up so. She is descended from son of the first marriage on her paternal side.

So, she and her aunt are confirmed matches with my husband on her maternal line, she could have turned out to be a match with me on her paternal side as well, but is still fairly closely linked. Also, she is connected to both my husband and me (by marriage, at least). This would put her in a very similar situation to our children and any children you and your wife may have - connected to a match through both of the parents.

I would never have realised if she hadn't contacted me again, as I have no access to her tree.

Regards Margaret

[Eric Hatfield]

That's an interesting story, Margaret. Perhaps these double connections aren't as uncommon as we think. I may see if I can find some research on the subject.

[Eric Hatfield]

Hi Margaret, just another example. (Now my mind is open to it, I can see these strange coincidences in more than one place.)

I have a good match on My Heritage (call him D) - 12 segments totally 219 cM. I wrote to D and found that he was my first cousin twice removed, on my father's side (his great grandfather was my father's brother, but my father was born 20 years after his GGfather, so he has 4 generations to MRCA and I have only 2). So that relationship is quite clear.

But when I check on the MH chromosome browser, D has three smaller segments in common with my maternal cousin (largest = 13 cM) , and 3 more different segments in common with my maternal aunt (largest = 32 cM).

I know of no other connection between my father and mother's families (though they all did for a time live in Melbourne) yet there are these DNA connections. 32 cM isn't a small segment, and if I add up approximately the total matches between D and them, they would be about 36 cM (cousin) and 52 cM (aunt). That would suggest relationships about 4th cousin and 3rd cousin once removed, which both fit with a MRCA 5 generations back.

I'm not aware of such a connection, but I know my father's family tree very well, and probably know enough of my maternal grandfather's tree (which it has to be since my aunt is actually only a half aunt) that I ought to be able to find this connection. It is very curious to me, and I will let you know if I can find anything, just out of interest.

[sugarfizzle]

Stranger and stranger.

This is interesting -

https://www.rootschat.com/forum/index.php?topic=806288.new#new

 

Regards Margaret

[Eric Hatfield]

Hello again Margaret,

I saw your link, thanks and I may comment there too, maybe.

This is starting to worry me. The info in my last comment was from my chromosome browser, where I compared my maternal aunt (A), my maternal cousin (C) and my paternal first cousin twice removed (D). I will focus here on the A-D match.

On my browser, I match with both of them on three segments. One I can read off the value, but the others are only partially overlapping so I have to estimate. The 3 segment values in cM are 32.0 and approximately  6 and 12, a total of about 50 cM. There could possibly be other segments in common between A & D which I don't share and so don't appear on my browser.

So I thought I would check that, and looked up A's DNA results, where D should (on the basis of my browser results) be one of the top matches. But D doesn't appear at all on A's DNA list, not if I search, not at all.

How can that be? Am I missing something, or is there some glitch here somewhere?

Any thoughts? Perhaps I should see if there's a My Heritage forum and ask there.

[sugarfizzle]

Eric, On this forum I usually concentrate on the practical results of DNA testing, especially when I can compare someone else's experiences with my own.  I don't fully understand the science of DNA, only the basics. And as I get older, even simple concepts can appear difficult to me.

But what you have described sounds impossible. If A and D match each other, then D and A should match each other, or are we both missing something obvious?

I hope someone else has some thoughts on the subject.

Regards Margaret

[Eric Hatfield]

Hello again Margaret,

I've been thinking more about it, and I was wrong. It was a beginners' mistake and I fell into it.

D and A both match me on the same segment, but that doesn't mean they match each other there, for there are two sides to every chromosome. We can only know that A & D are related if they match each other on that segment, which they don't.

So I relate to A on one side of that chromosome and to D on the other side of that chromosome, so I got some of that DNA from each of them, but it is different DNA, and they are not related.

It was a silly mistake, but I made it anyway. Let that be a lesson to me!

[stevemiller]

Hello Eric,

This is the key concept about DNA which I have trouble getting focused in my mind.

I don't know why, but what you have written just seems clearer than anything else I've read.

Hopefully, getting my Mum to do a test over Christmas will clarify a great deal.

My academic background is history rather than science, so I'm on a steep learning curve - like many others, I suspect!

Thanks
Steve