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.

Filter by
Sorted by
Tagged with
11
votes
3answers
2k views

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 ...
4
votes
1answer
690 views

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: ...
17
votes
1answer
662 views

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 ...
8
votes
3answers
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 ...
2
votes
0answers
349 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 ...
11
votes
4answers
327 views

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 ...
8
votes
1answer
1k views

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 ...
5
votes
2answers
193 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). ...
3
votes
1answer
4k views

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 ...
2
votes
1answer
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 ...
9
votes
1answer
619 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 ...
3
votes
2answers
253 views

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 ...
1
vote
1answer
233 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 ...
15
votes
1answer
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 ...
8
votes
2answers
13k 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 ...
5
votes
3answers
868 views

Determining where particular parts of ethnicity percentage from DNA come from in family?

I completed a DNA test, and the results stated that I am 77% African 20% European 2% Native American and 1% Asian. From the results of this test, is there anything in the results that would tell me ...
0
votes
1answer
200 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 ...
11
votes
2answers
777 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 ...
8
votes
2answers
312 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 ...
8
votes
3answers
315 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 ...
7
votes
3answers
22k 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 ...
5
votes
1answer
299 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 ...
4
votes
2answers
52k 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 ...
4
votes
1answer
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 ...
4
votes
1answer
1k views

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 ...
3
votes
1answer
2k 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 ...
3
votes
1answer
19k 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 ...
3
votes
3answers
30k 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 ...
10
votes
5answers
11k views

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 ...
10
votes
3answers
37k views

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 ...
6
votes
1answer
200 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 ...
5
votes
1answer
69 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 ...
3
votes
2answers
2k 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 ...
3
votes
1answer
57 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 ...
3
votes
1answer
335 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, ...
1
vote
1answer
72 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 ...
1
vote
1answer
125 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 ...
1
vote
2answers
225 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 ...
1
vote
1answer
783 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 ...
0
votes
2answers
101 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.
0
votes
1answer
235 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?
-1
votes
2answers
706 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 ...