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General => Ancestral Family Tree DNA Testing => Topic started by: Gadget on Sunday 04 November 18 13:45 GMT (UK)
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I have a known 3rd cousin who is recorded as sharing 292 cMs/18 segments with me. This is much higher than any of the other 3rd cousins in this line (all descended from daughters of our 2 x greats). The others are within the range 124-169 cMs. Even my known second cousins are lower than this (199-226).
I've checked to see if we have another line in common but have not found any cross over so far (back to 1770s).
The Bettinger chart suggests a range of 0-217 for 3rd cousins, and puts 292 as way out of the expected range. Do any members have similar measures for 3rd cousins?
Gadget
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It does seem very high.
I have a 2nd cousin once removed we share 112
and a 2nd cousin 196 cm
Both are descended from my grandmother's brother
Ancestry estimates them both as 3rd-4th cousins so these are on the low side for our confirmed relationships
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Although there's no documented double relationship, could the daddy however many generations ago be someone other than the husband? I'm not suggesting incest, but kissing cousins perhaps?
Jane :-)
And on another topic, I think roller skating morris dancing could catch on ;)
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At which company or database? They seem to add up the totals differently from each other.
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Thank you for replies.
Hurworth - all are Ancestry.
Jane - One of the other 3rd cousins has this one as 94cMs, so it can't be this particular line can it or the others would probably have the same high cM with him?
I'll have to delve a bit deeper. The 3 x grandparents of both sides (i.e. a generation further back from our common ancestors) seem to have produced an amazing number of DNA matches. I'll see if I can find some matches that don't link to the other 3rds.
Gadget
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Looking for examples in the matches at Ancestry we have on one kit:
3C1R who shares 119 cM across 5 segments
3C who shares 109 cM across 4 segments
3C1R -100 cM across 6 segments
3C - 98 cM across 5 segments
3C1R - 97 cM across 3 segments
Another kit:
3C - 202 cM across 7 segments
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I've tried to do a small tree to show cMs. I've just picked out 3 other cousins form this line.
(All Ancestry)
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Was AS the first-born? Might conception have predated marriage?
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It was 7 months after marriage but my lines that are unrelated to the other 3rd cousins from this line weren't in the same area. So it's not that.
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I know that DNA is not an exact science, but surely it is impossible to inherit more than 6.25% DNA from 2G grandparents (I am very much open to correction here).
AncestryDNA use the total number of cM as 3475.
That said, you can't share more than 3475 x 6.25%, which is equal to approx 217.2 cM with a 3rd cousin (Blaine Bettinger says 217 cM, as you say)
By that reasoning, I would suggest a bit of extra marital relationship on the side at some stage. Or, perhaps, more likely, incest.
Or a mistake in one of the trees!
My reasonings may be faulty, happy enough if anyone corrects me!
Regards Margaret
Modified. Or have Ancestry got it wrong? If your match uploads elsewhere, you will be able to see whether they agree or not.
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6.25% is the statistical average. In theory it could be as much as 50%. Although it is unlikely, it is statistically possible but if you have 100 coloured marbles, half blue and half red, all the red ones could be passed down to the Next Generation and continually after that. It is unlikely but statistically possible.
Martin
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Thanks for latest comments. I have done a pretty thorough paper trail check on that line as it's the most heavily populated! This line has been thoroughly researched by many cousins and we've all checked each others' work ;D
After the 2xgreats' generation, the offspring went their separate ways and seem never to be in the same place (Wales-Yorkshire-Staffordshire). Also the dates don't fit. At that generation or before, any sexual encounters between close relatives would likely show up in the cMs of the other cousins.
I'm currently trying to contact another cousin of that family/generation to find out how they match. Also, I'm trying to investigate more about the ancestry of AS's husband's line. It could be that the husband's line is related to one of my grandmother's lines pre-1770/90; possibly a Cash-Williams link.
Gadget
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I've just checked with b2 (only made contact a month ago!) in my diagram above and she is my 3rd cousin once removed, so have adjusted the diagram.
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6.25% is the statistical average. In theory it could be as much as 50%. Although it is unlikely, it is statistically possible but if you have 100 coloured marbles, half blue and half red, all the red ones could be passed down to the Next Generation and continually after that. It is unlikely but statistically possible.
Martin
Thanks, Martin. I thought as I was writing that something had gone wrong with my reasoning, which was why I said twice that I was open to correction!
My brain doesn't get into gear sometimes.
Regards Margaret
Modified:
Taking it to the next generation -
https://www.google.co.uk/amp/s/amp.reddit.com/r/23andme/comments/9cv78s/do_we_inherit_5050_from_our_parents/#ampf=undefined
visualtim Sep 4, 2018, 8:17 AM
Here's a simple analogy:
You have 100 blue marbles in a jar on your left: this represents your father's genome. You 100 red marbles on your right: these are your mother's. Close your eyes and pick 50 marbles from each jar and put them in a new jar: your jar.
Now count them. It's obvious you should have 50 red and 50 blue marbles in your jar.
Now, you have a kid. Close your eyes and reach into YOUR jar of red and blue marbles. Take out 50. Now open your eyes and count how many of red and blue marbles you gave to your child. In an ideal world, it's 25 blue and 25 red. But since it's random, it could be 20/30 or 26/24. It's even possible, but highly improbable, to have 50/0.
Regards Margaret
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Have you looked at this website ? https://dnapainter.com/tools/sharedcmv4 (https://dnapainter.com/tools/sharedcmv4) one of the useful features is that you can enter the number of shared cM's and it will give you the percentages of likely hood for each direct relationship.
Richard
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Thanks,Richard. I use it often and you must have missed my reference to it in my original post.
The Bettinger chart suggests a range of 0-217 for 3rd cousins, and puts 292 as way out of the expected range. Do any members have similar measures for 3rd cousins?
Gadget
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Thanks,Richard. I use it often and you must have missed my reference to it in my original post.
It didnt tie it to this website :-) but it was more the likelyhood percentages that i was really refering to rather than just the chart.
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Update:
After many weeks of searching for a second connection that didn't involve the other two 3rd cousins, I've finally found the explanation :)
The main relationship was through my father's father's mother and siblings (my grt grandmother) . I now find that my father's mother's grandmother was related to his mother's paternal line, as in this:
It could be that the husband's line is related to one of my grandmother's lines pre-1770/90; possibly a Cash-Williams link.
I think it's dble 3rd cousin
Gadget