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Author Topic: Are you 100% related to your DNA matches on Ancestry?  (Read 3416 times)

Offline ConfusedMason

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Are you 100% related to your DNA matches on Ancestry?
« on: Monday 27 May 19 04:35 BST (UK) »
There is a girl I work with who comes out to a DNA match of 8cm with myself. I am also a DNA match of her mothers as well.

My Parents have taken the DNA test too but are not related to her.

Are 8cm just statistical anomalies that you are probably not related to because the CM is too small?

Offline sugarfizzle

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Re: Are you 100% related to your DNA matches on Ancestry?
« Reply #1 on: Monday 27 May 19 10:39 BST (UK) »
The only way to establish this is to work out family trees of both of you, to see if there is an obvious connection.

It is a very small match, so may not be significant, however, it may be significant.

Even if you work out a common surname, that may not be where the match lies.

Look at matches you share with your colleague at lower levels (at Ancestry you usually only get shared matches at 20 cMs and above).

Since matches this small could relate to mutual 7G grandparents or beyond, the likelihood of you finding the connection isn't very strong, but you might strike lucky.

Regards Margaret
STEER, mainly Surrey, Kent; PINNOCKS/HAINES, Gosport, Hants; BARKER, mainly Broadwater, Sussex; Gosport, Hampshire; LAVERSUCH, Micheldever, Hampshire; WESTALL, London, Reading, Berks; HYDE, Croydon, Surrey; BRIGDEN, Hadlow, Kent and London; TUTHILL/STEPHENS, London
WILKINSON, Leeds, Yorkshire and Liverpool; WILLIAMSON, Liverpool; BEARE, Yeovil, Somerset; ALLEN, Kent and London; GORST, Liverpool; HOYLE, mainly Leeds, Yorkshire

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Offline Craclyn

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Re: Are you 100% related to your DNA matches on Ancestry?
« Reply #2 on: Monday 27 May 19 10:45 BST (UK) »
You would have to put a lot of work in to figure out where the connection might be with a match of 7cM. Are either of you able to narrow it down by looking at matches you have in common or eliminate some possible lines by looking at geographical locations?
Crackett, Cracket, Webb, Turner, Henderson, Murray, Carr, Stavers, Thornton, Oliver, Davis, Hall, Anderson, Atknin, Austin, Bainbridge, Beach, Bullman, Charlton, Chator, Corbett, Corsall, Coxon, Davis, Dinnin, Dow, Farside, Fitton, Garden, Geddes, Gowans, Harmsworth, Hedderweek, Heron, Hedley, Hunter, Ironside, Jameson, Johnson, Laidler, Leck, Mason, Miller, Milne, Nesbitt, Newton, Parkinson, Piery, Prudow, Reay, Reed, Read, Reid, Robinson, Ruddiman, Smith, Tait, Thompson, Watson, Wilson, Youn

Offline ConfusedMason

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Re: Are you 100% related to your DNA matches on Ancestry?
« Reply #3 on: Monday 27 May 19 12:29 BST (UK) »
Oh, well I'm not too interested in finding out a Family Tree way of seeing how we match, it doesn't interest me too much since I know it would be far too much work.

It was mostly querying the accuracy of such low CM matches. Could it match you with someone you aren't related to at all?

Offline Craclyn

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Re: Are you 100% related to your DNA matches on Ancestry?
« Reply #4 on: Monday 27 May 19 12:38 BST (UK) »
At that distance it could either be a real match or a false positive.
Crackett, Cracket, Webb, Turner, Henderson, Murray, Carr, Stavers, Thornton, Oliver, Davis, Hall, Anderson, Atknin, Austin, Bainbridge, Beach, Bullman, Charlton, Chator, Corbett, Corsall, Coxon, Davis, Dinnin, Dow, Farside, Fitton, Garden, Geddes, Gowans, Harmsworth, Hedderweek, Heron, Hedley, Hunter, Ironside, Jameson, Johnson, Laidler, Leck, Mason, Miller, Milne, Nesbitt, Newton, Parkinson, Piery, Prudow, Reay, Reed, Read, Reid, Robinson, Ruddiman, Smith, Tait, Thompson, Watson, Wilson, Youn

Offline sugarfizzle

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Re: Are you 100% related to your DNA matches on Ancestry?
« Reply #5 on: Monday 27 May 19 12:41 BST (UK) »
The simple answer is yes.

There is IBD, identical by descent, i.e. you are related to your colleague with common ancestors, possibly as far back as 7G grandparents or further.

Also IBS, identical by state, i.e. you match because you are from the same region, DNA handed down through the generations in perhaps the same cM block.

As Craclyn says, a lot of work. Unless you both trace all your 7G grandparents, or find a match in common, you are unlikely to find the connection.

Regards Margaret
STEER, mainly Surrey, Kent; PINNOCKS/HAINES, Gosport, Hants; BARKER, mainly Broadwater, Sussex; Gosport, Hampshire; LAVERSUCH, Micheldever, Hampshire; WESTALL, London, Reading, Berks; HYDE, Croydon, Surrey; BRIGDEN, Hadlow, Kent and London; TUTHILL/STEPHENS, London
WILKINSON, Leeds, Yorkshire and Liverpool; WILLIAMSON, Liverpool; BEARE, Yeovil, Somerset; ALLEN, Kent and London; GORST, Liverpool; HOYLE, mainly Leeds, Yorkshire

Census Information is Crown Copyright, from www.nationalarchives.go

Offline Guy Etchells

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Re: Are you 100% related to your DNA matches on Ancestry?
« Reply #6 on: Monday 27 May 19 12:42 BST (UK) »
Quote from: ConfusedMason on Monday 27 May 19 12:29 BST (UK)
Oh, well I'm not too interested in finding out a Family Tree way of seeing how we match, it doesn't interest me too much since I know it would be far too much work.

It was mostly querying the accuracy of such low CM matches. Could it match you with someone you aren't related to at all?



Yes some low CM matches could point you to people you are not related to.
I expect the chance of this happening will reduce as the science of DNA develops and the tests get more refined, but it will be a long process.

In a similar vein some DNA from direct ancestors whose DNA you could have inherited will not be present in your DNA. This is due to the random way DNA is passed from parents to their children.
Cheers
Guy
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Offline ConfusedMason

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Re: Are you 100% related to your DNA matches on Ancestry?
« Reply #7 on: Monday 27 May 19 12:52 BST (UK) »
Interesting, thanks everyone.

I'll let her know we probably aren't related, just statistical noise.
She thought it was a sure thing since it said I was related to her mother as well.

DNA is weird.

Offline clayton bradley

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Re: Are you 100% related to your DNA matches on Ancestry?
« Reply #8 on: Monday 27 May 19 12:53 BST (UK) »
Ancestry Thrulines have found me a number of matches at 8cM which are accurate and I wouldn't have picked up on. One set of three, cousins to each other, descended from a Marguerite Howland whose ancestor was halfbrother (different mothers) of my 4xggfather and (slightly higher cMs) a set of 4, cousins to each other but not previously known to each other, descended from my 2xggmother's nephew. cb
Broadley (Lancs all dates and Halifax bef 1654)
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