Questions tagged [dna]

For questions about using DNA to further knowledge of family history, relationships, ethnic origin, and overall ancestry. Most common tests include Y-DNA, mitochondrial DNA, and autosomal DNA.

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Determining likely relationship based upon autosomal DNA shared cM

Given two tests that share some cM of autosomal DNA, how can I easily find the predicted relationships that such shared cM would suggest? For example, a 2,200 cM match suggests it could be either: ...
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11 votes
3 answers
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Generational Loss of Data with DNA Testing

I have personally done the Y-DNA, the add-on Y-block with FamilyTreeDNA, mtDNA, and new FamilyFinder/AncestryDNA (via Ancestry) which i plan in transferring to FamilyTreeDNA just recently as a base ...
CRSouser's user avatar
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17 votes
1 answer
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How can DNA testing aid me in my genealogy research?

My basic understanding of DNA testing is that it can tell you where your ancestors came from. How can just knowing the ethnic breakdown of my ancestors help me? What if I already know where my ...
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8 votes
3 answers
2k views

Interpreting X DNA?

I guess I need a "dumbed down" explanation of these things, since I don't understand the explanations I've read. First, I have a 3rd cousin match from Ancestry who uploaded his info for me on ...
Debbie Foss's user avatar
2 votes
0 answers
363 views

Autosomal DNA Chromsome Browser - Is there such a thing as a 'family trait' of shared segments?

I realize the passing of genes is approximately 50/50 (reference Generational Loss of Data with DNA testing) with each generation and which genes are passed are commonly referred to as 'random' based ...
CRSouser's user avatar
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11 votes
5 answers
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What DNA data is important to record?

When DNA testing is done for genealogical purposes, they send back reports with all sorts of incomprehensible information. I want to save the important information with the person in my genealogy ...
lkessler's user avatar
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9 votes
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653 views

My Father passed away - next test(s) on what remains of his DNA sample?

I posted this general question over at the forum on FamilyTreeDNA. Though I received a reply, there is still no answer to my question, so I thought I'd try my luck at posting here. Anyhow, in early ...
user4707's user avatar
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8 votes
1 answer
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Working with autosomal DNA results

I have the automsomal DNA results for myself, 3 full sisters and 1 half-sister. We all share a mother, and we all tested with familytreeDNA. Our results are uploaded to gedmatch.com. Our parents are ...
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5 votes
2 answers
208 views

Explaining risks when seeking DNA testing by cousin?

It has recently occurred to me that I have been in intermittent contact with a second cousin who shares my father Y-DNA (subject to any mutations in the last two generations, which should be slight). ...
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1 answer
2k views

What would the starting shared cM number be for abnormally close relationships in Autosomal DNA test?

I have seen in the examination of family trees where individuals sharing a great grand parent marry and have children, somewhat commonly in pre-American Civil War, which I would think would create ...
CRSouser's user avatar
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What is considered a strong match on a Big-Y DNA test?

I have done Big-Y on FamilyTreeDNA for a single individual and considering others as well as using the YFull interpretation service without fully understanding how to use it because I wanted to ...
CRSouser's user avatar
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3 votes
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Probability of Specific Relationship from AncestryDNA?

I have a DNA match on Ancestry.com that shows a possible 1st or 2nd cousin match at the level of 684 cM's (just barely inside the 680 - 1150 range) and across 29 strands of DNA for 1st cousin. There ...
TommyJoeK's user avatar
1 vote
1 answer
258 views

Determining if siblings are half siblings or full siblings?

I recently found 6 siblings 4 who are half and 2 who may be full. My sister was born in 1949, I was born in 1950 and my brother in 1952. The other siblings all know who both their parents are. The ...
P. Stephens's user avatar
-1 votes
1 answer
53 views

How can I share more DNA with a distant cousin's son than with the distant cousin?

My Heritage has brought up a 0.6% match with a suggested son of a 3rd Cousin / 4th Cousin. He is aged under 20. Their tree is managed by the father aged in his 40's. However, there is only a 0.2% ...
Nevil Pearce's user avatar
15 votes
1 answer
4k views

Proving Native American ancestry using DNA testing?

I saw on The Generation Project where a man took a DNA test that showed he was some percentage Native American or was the chance that he as Native American. Can a DNA test prove that I have Native ...
Blake Christensen's user avatar
11 votes
2 answers
873 views

Asking distant cousins for DNA?

In my family we have a DNA contradiction – two cousins (at about the 4th cousin level) took a Y-DNA test, but did not match and had two completely different haplogroups. Since then, I have traced ...
Hammy's user avatar
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11 votes
6 answers
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How to get an elderly person to provide saliva sample for DNA?

I have an Ancestry autosomal DNA kit that we are trying to get a 95 year old woman to take and having trouble. I provided the hints that 23andme offers to my cousin that is trying to administer the ...
WilliamKF's user avatar
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10 votes
2 answers
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What is the significance of "shared centiMorgans"?

I've had my autosomal DNA tested and the site I've used (FamilyTreeDNA) tells me that I have a "Shared centiMorgan length" of 48.08 with my closest match and the "longest block" is 28.89. FamilyTree ...
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8 votes
3 answers
327 views

"Resolution" of DNA testing

What is the spatial/cultural "resolution" of DNA testing for genealogical purposes? How finely can it be used to estimate where a particular person's ancestors were from? I am interested in testing ...
Gene Golovchinsky's user avatar
8 votes
2 answers
17k views

Genetic Distance to Generations Calculation for Y-STR DNA tests

As a follow-up to the Q&A on Generational Loss of Data with DNA Testing, which described generational detail loss really well for Autosomal, I am now looking for a calculation or some basic ...
CRSouser's user avatar
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8 votes
2 answers
324 views

What factors should I consider when choosing a DNA-testing service?

I and my half-sister are considering having DNA testing done, for the following primary reasons: To attempt to identify my sister's paternal line. We have no information about her father, who may be ...
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8 votes
3 answers
23k views

How to interpret a reasonable X DNA Match, but no shared cM Autosomal result on GEDMatch?

I recently uploaded one of the Autosomal DNA results I manage to GEDMatch.com and ran the X-Match routine and came up with a puzzling result. The strongest result by far on the test has 37.2 shared ...
CRSouser's user avatar
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7 votes
6 answers
14k views

Can Ancestry.com DNA matches be wrong

I (female) had an unexpected half sister match (1,866 cM across 49 segments) in Ancestry.com. We are about the same age so I'm assuming sibling. Upon closer examination I realized my brother(A) was ...
J Joan's user avatar
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6 votes
1 answer
256 views

Y-DNA match a false positive?

I completed a Family Tree DNA test for Y-DNA. My results show I have only six matches. I have viewed the available trees of 4 of the 6 trees, the others are private and unwilling to cooperate. I ...
Rod Farrell's user avatar
5 votes
2 answers
134 views

Isolating DNA segments related to specific ethnicity-location

Almost all genetic genealogy websites will tell you the origins of your DNA. But I would like to go one step further and find out which parts/segments of my DNA are related to a specific ethnicity. I ...
TJinBC's user avatar
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5 votes
1 answer
121 views

Using DNA to link individuals after a name change

How do I go about using genetic testing to support (or disprove) the identity of an individual before a name change? My great-great-grandfather, Everett T Malcom, would just say, "It's me own ...
βenjamin's user avatar
5 votes
1 answer
363 views

What GEDCOM tag should the DNA Haplogroup be stored?

I was reviewing the GEDCOM 5.5 specification and I am not clear as to what field should be used to store the basic Haplogroup information for an individual from DNA testing as described in What ...
CRSouser's user avatar
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4 votes
2 answers
56k views

How many generations back will specific ethnicity show up in DNA?

When getting a DNA test, how many generations back will a specific ethnicity show up? Our family tree shows that our 5th great grandfather was African. My cousin just received her DNA results ...
user6176's user avatar
4 votes
1 answer
3k views

Is ancestry.com DNA test accurate with respect to native american descent?

Both myself and my wife believe we are descendants (each on the order of 1/16) of native americans, yet for the Ancestry.com autosomal DNA test, the ethnicity estimate shows nothing for native ...
WilliamKF's user avatar
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4 votes
1 answer
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What settings to use in GedMatch to confirm a seventh generation relative sharing DNA?

I have a relative, Nancy Ann Trigg, who is 7 generations removed from me, so I expect I have one part in 2^7 (128) of her DNA in my autosomal DNA test. I want to confirm this relation and found ...
WilliamKF's user avatar
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3 votes
2 answers
3k views

How can genetic relatives be related to both maternal and paternal sides, but not each other?

I am completely ignorant to all of the genetics of ancestry, although I have a keen interest in family history. I did a DNA test through 23andme, as did my mother and a paternal aunt. In my list of ...
breeis's user avatar
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3 votes
1 answer
63 views

Are there different amounts of "fuzziness" in the endpoints when doing pairwise 1-1 comparisons among three people at GEDmatch?

I was performing a triangulation at GEDmatch and obtained the following start and end points for the triangulated segment on Chromosome 1 for each comparison: Person A with Person B: 19,899,991 ...
Barry's user avatar
  • 670
3 votes
3 answers
32k views

Possible half-sibling based on matching Centimorgans

I have been using Ancestry.com for years. A year back I submitted my DNA test. I have had quite a few matches that land in the distant relative to 3rd or 2nd cousin range. Recently, I was notified ...
WSchroeder's user avatar
3 votes
1 answer
362 views

How is this relationship likely to be 'identified' by a DNA testing company?

I have recently made contact with a putative (half)-first-cousin with whom I may share a grand-father. There is not a definitive documentary trail that confirms her grandfather and mine are the same, ...
user avatar
3 votes
1 answer
23k views

What is expected shared cM of cousins with only one shared grandparent?

Related to What is expected shared cM of double third cousins?, what would the expected range and average shared cM be? In this case, I'm seeing 64.0 cM over 3 segments. Looking at the table, that ...
WilliamKF's user avatar
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3 votes
1 answer
4k views

What is expected shared cM of double third cousins?

I've come across double third cousins, who are third cousins through two different routes as the same two families had two separate marriages between them that leads to this situation. For DNA ...
WilliamKF's user avatar
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1 vote
1 answer
100 views

2nd cousins. One 4%, one 8%?

I’ve recently been matched to two second cousins by DNA. However one shows a 4% match and the other one shows an 8% match. One is on my father’s side and one is on my mother’s side. Why, or how is ...
user10812's user avatar
1 vote
1 answer
709 views

What would the cM range be for persons sharing the same mother and the fathers are brothers?

I had a swab test performed to establish sibling-ship through DNA Diagnostic Center (DDC) wanting to confirm what I thought was certain paternity with myself, male sibling and and mother (father ...
Desparete For Assistance's user avatar
1 vote
2 answers
302 views

Does 1,864 centimorgans indicate half-siblings? [duplicate]

My sister, daughter and I all took DNA tests for fun. My sister and I show up on Ancestry as "close family," and share 1864 Centimorgans, and we do not share any relatives that my daughter and I share ...
ejohns48's user avatar
1 vote
1 answer
2k views

Ancestors missing from ThruLines?

At AncestryDNA, until a few days or so ago, all my expected direct ancestors were listed correctly by ThruLines. Now when I look at them some of them have gone missing. For example, today I can only ...
PolyGeo's user avatar
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0 votes
1 answer
110 views

Conflicting information about my husband's maternal grandmother's ancestry/DNA

We have had a ton of research done on my husband's maternal grandmother, Emma Louise Radunz Frank. She was born in Menominee, Michigan on May 24, 1894. The research done all shows that she was ...
marilyn91's user avatar
0 votes
1 answer
216 views

Interpreting DNA Results from 23andMe?

I received my results from 23andMe and I read and read and I just don't understand. I wondered if you could help me? My Mother is 91 years old and never knew who her birth father was. We took the ...
Pamela's user avatar
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0 votes
1 answer
485 views

Can I do the 23 and me spit test after a prolonged fast?

If I fasted for 90 hours beforehand (instead of eating regularly every day), would it affect my 23 and me DNA spit test kit results?
user3002453's user avatar
0 votes
2 answers
145 views

Understanding DNA match of 1,723 cM

I have a DNA match of 1,723 cM with a male 6 years younger than me. His father is one of a twin, could my match be not my half-sibling but my 1st cousin.
Lorraine Wingate's user avatar
-1 votes
2 answers
875 views

Interpreting DNA test that shows mother was 1/3 Jewish?

I'm assuming that my mother's mother was full or 2/3 Jewish for my mother to end up being 1/3 Jewish. So what does that make me (her son)? Would I be considered to be of Jewish decent if my mother is ...
bobf's user avatar
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