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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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1answer
36 views

Can ‘junk DNA’ be tested to arrive at genealogy insights?

I’m intrigued as to how much ‘junk DNA’ differs between relatives and wonder which DNA testing companies offer such tests?
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1answer
30 views

Deducing relationship from DNA results for two matches at two different websites?

My father was adopted and, while I’ve had my DNA tested, he is not quite ready to do so. I’ve found some fairly close matches, one that shares 9.8% (692.7 cM) and another that shares 14.4% (979 cM). ...
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1answer
21 views

Interpreting results of siblingship test?

My sister and I suspect we have different fathers. We took a siblingship test through DDC. The results are a little confusing and honestly, they put our wet swabs each in a paper envelope and then ...
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3answers
47 views

DNA match higher with a younger generation of the family

I have a 107 cM match with Eli. His mother is Lily and Lily's brother is Henry. Henry's son is Henry Jr and his grandson is Kevin. I have a 235 cM match with Kevin. Kevin is one generation younger ...
3
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1answer
57 views

Possible Half Sibling

I was adopted as a small child and have never known my natural mother or father. I recently completed an AncestryDNA test and have been matched against a lady with a score of 1,912 cM across 73 ...
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1answer
61 views

Can the amount of saliva affect how many centiMorgans are shared between 1st cousins?

I share 279 centimorgans with a 1st cousin in 12 segments. I don't believe that is enough to be considered 1st cousins. She says she couldn't spit a lot. Would a small amount of spit affect the ...
3
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1answer
57 views

How can 3/4 siblings share a mother but not paternal ancestry?

My family is running the DNA test gauntlet and my dad got back some interesting results. He is related to his half sister (1,687 cM across 66 segments) at a level that is to be expected. He is ...
3
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1answer
46 views

Which type of DNA test could help spot ancestry from father's great-grandmother?

My father and his sisters have claimed that their great-grandmother was of a different race from the rest of my family. I've tried 23andMe, and I didn't see any interesting results at 3% of my ...
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2answers
52 views

Understanding second cousin predictions from AncestryDNA?

I have three extremely high second cousin predictions from my father's side. I do not know my anything about my biological father (Name, age, etc..). My top matches are: R - 619 cM across 39 ...
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1answer
64 views

Sisters who match to me have very different centimorgans?

I have done a DNA test and show a 2nd cousin match with 313 cM and then a 4th cousin match with 67cM yet these two matches are sisters with the same parents. How is this possible?
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0answers
41 views

Understanding DNA ethnicity result?

I have been trying to understand a DNA result and have been reading lots of info and asking questions of Ancestry.com. Still not finding an explaination that will help me move forward. I apologize if ...
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1answer
66 views

Understanding West Eurasian DNA when no European ancestry?

A DNA land and GenePlaza DNA test reports that I am 73% South Asian, 24% Central Asian and 2.8% Mediterranean Islander. It then concludes that I'm mostly West Eurasian. How is this possible when I ...
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1answer
61 views

Why do parent and child share more cM than full siblings?

According to the shared cM project, a parent and child share 3330-3720 cM (99th percentile). Full siblings share 2209-3384 cM (99th percentile). In other words, almost all people share more DNA with a ...
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1answer
45 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?
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2answers
219 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 ...
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2answers
84 views

Are there general notions of distance between individuals in a genealogy?

The terminology Nth cousin Mth removed is common, but I was wondering if there are other notions of "distance" on genealogies? For example looking at the Cousin tree (with genetic kinship) chart at ...
6
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1answer
64 views

Working with DNA results for multiple profiles across multiple sites

I manage a number of DNA profiles (for related individuals) across a number of sites: FamilyTreeDNA (5 profiles) MyHeritage (5 profiles) LivingDNA (2 profiles which will increase to 5 in the near ...
4
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1answer
52 views

Interpreting matches with low cM values and high SNPs (or vice versa)?

On GEDmatch's autosomal one-to-one report, a match contains a column for cM and a column for SNPs values, for each of the matching chromosomes. Normally you look for high cM values as an indicator of ...
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2answers
105 views

Finding Korean War-Baby Brother using GEDmatch?

My dad got a lady pregnant in Korea while he was in the war. When he got back, he tried to move her here but was unable to. He lost touch with her. For years, I have tried to find him but there was no ...
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1answer
79 views

If my great grandmother is Half Spanish what percent does that make me? [duplicate]

My Great Grandmother is Half spanish what percent would that make me?
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0answers
43 views

Interpreting runs of homozygosity data to determine how closely parents were related?

According to Gedmatch's Are your parents related? tool, my grandmother's DNA shows several runs of homozygosity (ROH): Chr Start Location End Location Centimorgans (cM) SNPs 3 180690286 ...
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2answers
118 views

Perplexing Shared DNA Data - First Cousin Once Removed or Half Niece?

My sister and I recently did DNA tests through 23&Me. We found out we have a surprise relative about 27 years younger than us (a generation younger). She has about 8.5% shared DNA or around 577 ...
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2answers
65 views

Triangulation with DNA Results - is something amiss?

My 1st cousin 1xR and my Aunt and I have all taken Ancestry DNA tests. For clarity sake I will refer to the parties as "Z", "N" and "R" "R" is related (by document) to "N" as nephew and Aunt "Z" is ...
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1answer
66 views

23 and Me DNA testing finding new (close) relatives

I did 23 and Me about a year ago and found a '2nd cousin' (according to their algorithm) who put his background as 'adopted and wanted to find birth family' I reached out to him. Let's call him AJ. ...
3
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1answer
73 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 ...
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2answers
66 views

Is DNA match 1st cousin or niece?

I have recently learned that my father is not my biological father. Please see the Ancestry DNA screenshot. The first person in red is listed as a first cousin but I know for a fact she is actually ...
4
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1answer
33 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 ...
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2answers
92 views

How much Chinese dna will show up on my dna test

I just got my results back from My Heritage. I have a picture of my Great Great Grandfather he definitely looks Chinese, his father was 100 percent Chinese and he married a Native American they would ...
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0answers
56 views

DNA not supporting linear genealogy between grandparent, child and grandson?

I am his grandmother and should have 300 or more cMs connection. However, we share only 18 or so cMs. My son, (my grandson's father), shares only 17.2 cMs. What's up?
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2answers
212 views

Interpreting 23andMe results for half siblings that share 45.5% of their DNA?

I was raised to believe that my half sister and I were in fact half sisters with different fathers. We both did 23andMe testing and the results conclude that we share 45.5% of the same DNA. we share ...
2
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2answers
123 views

No shared X DNA segments found

On FTDNA I match two other Stephens males with the exception of 1 marker over 67 markers. When the three of us uploaded our DNA to Gedmatch, mine from FTDNA Family Finder and theirs from Ancestry, we ...
2
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1answer
53 views

Are centimorgan contributions additive?

I share a 50 centimorgan 6 segment match to person "J". My maternal side aunt shares 54 centimorgan 5 segment match to that same person "J" I see two possible blood-line connections between my aunt ...
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0answers
98 views

Is aunt actually mother's half sister?

I was looking at a first cousin of mine after doing the 23andme DNA test and found that we only share 5.25% of DNA with him, and it believes he is a second cousin of mine. I checked my mom's DNA ...
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1answer
51 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 ...
6
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1answer
68 views

When triangulation is not transitive

I'm focusing on triangulation groups and so looking at matching segments that overlap each other. I'm frequently finding the situation where, at a single website, match A's segment is shown as ...
5
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1answer
73 views

Segments with no matches

I am beginning the process of forming triangulation groups, and I wonder: what do people do with segments on which there are no matches? I found such a segment already just on the first chromosome I ...
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0answers
19 views

Does 2% fall into the normal range of amount of DNA shared with a first half cousin? [duplicate]

Does 2% or 142 cm amount of DNA shared with a half first cousin add up? From what I’ve read, the amount of DNA shared between two half first cousins falls between 215-650 CMs or 4-7%. My other ...
6
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1answer
125 views

Reconstructing autosomal genomes of Mayflower passengers

I imagine no group of 100 people has been as genealogically documented as the Mayflower passengers. And with an estimated 35,000,000 descendants living today, the number of descendants genetic tests ...
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1answer
55 views

DNA results for half sibling

I had my DNA test done about 8 years ago with ancestry, I was contacted by a person who believed he could be my half brother from my father during World War 2, all the information he had said my ...
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2answers
207 views

Half sibling or 1st cousin?

I recently did Ancesty DNA to determine a match between me and a possible half sister. The results came back, and we share 1366 cM of DNA. As I’ve learned, this is on the low side for half siblings ...
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1answer
36 views

Percentages of nucleotides in raw DNA

I just had Excel compute the percentage of each nucleotide appearing as the first letter in each position in a raw DNA file. Then I had it compute the percentage of each nucleotide in the second ...
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2answers
76 views

Triangulation conundrum

I tested both my mother "M" and her brother "D" at FTDNA. I was looking through D's list of segments today for triangulated segments, using the matrix utility to help, and I found the following D ...
3
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1answer
46 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 ...
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1answer
77 views

Centimorgans shared with a great unclie

I have a 1400+ centimorgan Match to a great uncle on my father's side. Is it common to have this strong of a match to a great uncle? I have read this high number is usually shared with half-siblings,...
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1answer
204 views

Half Uncle Mystery

I discovered a match on ancestry.com that was a first cousin match to me on my fathers side but assumed it was his half sibling (we suspected existed.) We share 756 centimorgans. He is five years ...
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1answer
68 views

Is Whole Genome Testing in any way useful for Genealogy?

There are several DNA testing companies out there that are excellent for genealogists. These include Ancestry DNA, Family Tree DNA, MyHeritage DNA and 23andMe. These companies provide match lists of ...
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1answer
62 views

Phased psuedo-kit on GEDmatch — what accounts for huge drops in SNP count?

I guess first I should make sure I understand how GEDmatch stores raw data -- I'd guess that during "tokenization", GEDmatch turns my raw data file into a format that it likes, i.e., perhaps replacing ...
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3answers
137 views

DNA results from Ancestry

A friend of mine took a DNA test with Ancestry.com a while back. Now I (a trained mathematician) am being asked to help interpret the results, and I am finding myself totally out of my depth. The ...
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2answers
306 views

Is this close family member on AncestryDNA a half sibling?

on ancestry.com i got a "close family" match, with 1,430 centimorgans shared across 58 DNA segments - it says it could be a niece, aunt, or half sibling (range includes 1st cousin, but i have read ...
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1answer
130 views

Why would I match someone in a region neither of my parents do?

I was surprised to find someone show up in FTDNA as a 2nd-3rd cousin to me (168 shared cM, 34 segments with a minimum length of 5 cM) but not among the 17,667 matches of my father or the 18,178 ...