Author Topic: DNA what is the bare minimum in % for matches cms or segments ?  (Read 976 times)

Offline mona lisa

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DNA what is the bare minimum in % for matches cms or segments ?
« on: Friday 03 July 20 23:10 BST (UK) »
Is a DNA match of   say   7 cms 1 DNA segment  of any value in ancestor matches ?
Ire Co Arm Seagoe Drumon JOYCE/HOUSTON John/Isabella ELIZ/ARMSTRONG /Wm Valentine + Hannah Johnstone MILLER aft1840 in Glasgow Scot dau Isabella 1847 + John M'D s/o Co DERRY Edw McD*V*TT//DAID + Eliz M'CL*SKY/M'SHANE/TEMPLETON/DUFF Ire = DOYLE,Jos + Mary M'GINITY/ m ca1840 = Can PEI Hope Riv/ DOWDS,Bridget b ca1819 d/o John DOWD + Mary WOODS ca1840 PEI Can UK IOM Wales, Barry ISL= REINE/RIIM = Adrianoff/ Michal =Arthur/Mary/Mildred / /MEREDITH/ TRAV*S/GARNETT/VON Stiegler/VON STIEGLITZ

Offline Gadget

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Re: DNA what is the bare minimum in % for matches cms or segments ?
« Reply #1 on: Friday 03 July 20 23:26 BST (UK) »
It can be.  I have a few matches of 6cMs and have traced them to common ancestors.

See: https://dnapainter.com/tools/sharedcmv4

for possible relationships.

Gadget
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Offline mona lisa

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Re: DNA what is the bare minimum in % for matches cms or segments ?
« Reply #2 on: Saturday 04 July 20 06:23 BST (UK) »
Much appreciated   Gadget......information very helpful!
Ire Co Arm Seagoe Drumon JOYCE/HOUSTON John/Isabella ELIZ/ARMSTRONG /Wm Valentine + Hannah Johnstone MILLER aft1840 in Glasgow Scot dau Isabella 1847 + John M'D s/o Co DERRY Edw McD*V*TT//DAID + Eliz M'CL*SKY/M'SHANE/TEMPLETON/DUFF Ire = DOYLE,Jos + Mary M'GINITY/ m ca1840 = Can PEI Hope Riv/ DOWDS,Bridget b ca1819 d/o John DOWD + Mary WOODS ca1840 PEI Can UK IOM Wales, Barry ISL= REINE/RIIM = Adrianoff/ Michal =Arthur/Mary/Mildred / /MEREDITH/ TRAV*S/GARNETT/VON Stiegler/VON STIEGLITZ


Offline hurworth

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Re: DNA what is the bare minimum in % for matches cms or segments ?
« Reply #3 on: Saturday 04 July 20 07:49 BST (UK) »
I don't usually get interested in a 7cM match, but if they're matching a few of the known cousins I really like to have a better look at chromosome level, so NOT at Ancestry.

The extended family has had some breakthroughs with these very small matches from being able to see 'where' (on the chromosome) they're matching us, and who else these segments are shared with.  Actually, at  Ancestry you often don't notice them, because if they share under 20cM with all your known cousins you won't spot them.  One of the best ones appeared quite some way down the page at Gedmatch, but when I clicked on her 11 known descendants of my gtgtgtgt-grandparents were in her top 15 matches.  Turns out she is descended from my gtgtgtgt-grandfather's brother (which took a fair bit of record-digging to confirm).  None of us had noticed her at Ancestry even though she'd been on the matchlist for months.

Offline brigidmac

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Re: DNA what is the bare minimum in % for matches cms or segments ?
« Reply #4 on: Saturday 04 July 20 23:06 BST (UK) »
Not often linked but on ancestry i found some interesting matches when I used the surname match search function on ancestry it was an unusual me who a distant ancest+ had named as birth father of her child ,there were several trees with all cm matches who had this surname eventually found one with a full tree which traced back to same town and worked out the connection did correspond ,

On another branch while looking up my great great grandparents surnames +looking at trees I keep coming across another surname from earlier generation it could be a link but DNA matches will be small

Roberts,Fellman.Macdermid MCDERMID McDiarmid Gardner Jones ,Bloch,Irvine,Hallis Stevenson ,McKay

Offline melba_schmelba

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Re: DNA what is the bare minimum in % for matches cms or segments ?
« Reply #5 on: Sunday 05 July 20 12:43 BST (UK) »
Is a DNA match of   say   7 cms 1 DNA segment  of any value in ancestor matches ?
Even links of 5cM on GEDMATCH can be real. It's a question of how far back, and whether it goes back beyond when most people can practically trace a tree, and also, of whether it means much, when there might be hundreds of thousands if not millions of people who you share a 5 cM segment (or bigger) with. Given I have found 6cM link to people with common ancestors born in the late 18th century, but also 30cM links with people born in the late 17th century, I don't see why in theory a 5cM link could not also be from a common ancestor born in the early 19th century, but as far back as the 1300s.

Offline Meelystar

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Re: DNA what is the bare minimum in % for matches cms or segments ?
« Reply #6 on: Sunday 05 July 20 13:34 BST (UK) »
I think the answer has got to be it depends  ::)
I have identified one at 8cM, both our trees had the common ancestor with a fairly unusual name so obviously not a hard task! The relationship looks to be 4th cousins once removed.
I have other far higher matches though where things just arenít lining up  ???

Offline melba_schmelba

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Re: DNA what is the bare minimum in % for matches cms or segments ?
« Reply #7 on: Sunday 05 July 20 13:43 BST (UK) »
I think the answer has got to be it depends  ::)
I have identified one at 8cM, both our trees had the common ancestor with a fairly unusual name so obviously not a hard task! The relationship looks to be 4th cousins once removed.
I have other far higher matches though where things just arenít lining up  ???
See my comment above - I traced a group of 20-30 cM matches to a common ancestor born in the late 17th century. Most people do not have their tree traced back fully that far back. Even if they do maybe 2-5% of those ancestors will not be of the parent(s) they are meant to be from.

Offline avm228

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Re: DNA what is the bare minimum in % for matches cms or segments ?
« Reply #8 on: Sunday 05 July 20 14:59 BST (UK) »
Iíve been able to place a new 6cM match in my tree this morning. She is a 5th cousin once removed.
Ayr: Barnes, Wylie
Caithness: MacGregor
Essex: Eldred (Pebmarsh)
Gloucs: Timbrell (Winchcomb)
Hants: Stares (Wickham)
Lincs: Maw, Jackson (Epworth, Belton)
London: Pierce
Suffolk: Markham (Framlingham)
Surrey: Gosling (Richmond)
Wilts: Matthews, Tarrant (Calne, Preshute)
Worcs: Milward (Redditch)
Yorks: Beaumont, Crook, Moore, Styring (Huddersfield); Middleton (Church Fenton); Exley, Gelder (High Hoyland); Barnes, Birchinall (Sheffield); Kenyon, Wood (Cumberworth/Denby Dale)