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10 votes
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Where can I find a centiMorgans calculator?

There is a service to turn a physical chromosome position (measured in base pairs, "bp") into a linkage position (measured in centiMorgans, "cM") here: http://compgen.rutgers.edu/map_interpolator....
RobertShaw's user avatar
  • 3,877
10 votes

Why no DNA match with possible seventh cousin?

The amount of autosomal DNA shared by 6th or 7th cousins is quite small. Some will share no detectable DNA. The latest data of the Shared cM Project shows that seventh cousins share between 0 and 57 ...
Harry V.'s user avatar
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10 votes
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How to narrow down the best DNA donors in a large family?

I think you just posted that question to make all other genealogists envious of what you have to work with. :-) But seriously, yes, there are some things you should do and do as soon as possible (i.e....
lkessler's user avatar
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10 votes
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Explaining major discrepancy in genomic position between Gedmatch and MyHeritage?

It looks like this may be due to a difference in the Genome Builds (https://en.wikipedia.org/wiki/Reference_genome#Human_reference_genome) used between the two tools. GEDMatch reports that they ...
Erin Hill-Burns's user avatar
10 votes

Sharing 52% DNA with mother

This could also be explained if the parents share DNA. If you took the same test with your father and it also was > 50%, it could indicate they are distantly related. A single shared chromosome ...
rtaft's user avatar
  • 201
9 votes
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How to get an elderly person to provide saliva sample for DNA?

I had my 93 year old uncle take a test after he agreed to do it. I did not feel comfortable asking him to do it, or for me to attempt to administer it. My uncle was at a nursing home. I asked one ...
lkessler's user avatar
  • 16.8k
9 votes

Finding haplogroup through raw DNA data?

I obtained my Y-DNA haplogroup from my AncestryDNA raw DNA file using the first method detailed in this link: https://www.geneticgenealogist.net/2016/01/how-to-get-ydna-haplogroup-from.html In short,...
Kotoamatsukami's user avatar
9 votes

Does having child of DNA tested parent help find parent's DNA ancestors?

I think the prior answers are either misleading or wrong, and people should not miss out on the opportunity to get great DNA information because they were discouraged by those answers. If you have ...
Brainstorm's user avatar
8 votes

Is this adopted DNA match my niece or half sibling?

The adoptee is very likely your niece, specifically the half-sibling of the niece you have also tested. The relationship could be diagrammed as follows: The X-DNA is key to determining this ...
Harry V.'s user avatar
  • 18.9k
8 votes

Predicted percentages of shared DNA for DNA tests of half-siblings?

The ISOGG Wiki's article on Autosomal DNA statistics explains the concepts in the previous answer in much more detail -- and includes links to the AncestryDNA white paper that explains Ancestry's ...
Jan Murphy's user avatar
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8 votes

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

Absolutely not. The amount of saliva is a factor in whether or not you get DNA results at all. If you have them, that's it. While there is such a thing as "partial results" it's because you need ...
Cyn's user avatar
  • 2,446
7 votes

Is a half-sibling match on AncestryDNA reliable, or is more testing needed?

The result should be reliable in that it shows a close relationship. As shown on the Autosomal DNA statistics page on the ISOGG Wiki, the relationship is almost certainly one of these: one of you is ...
RobertShaw's user avatar
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7 votes
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What does 'DD' mean in a name on GEDmatch.com?

The "DD"-prefix simply means that they're a member of the Facebook group "DNA Detectives". It's a Facebook group for people who use DNA genealogy to track down family members. If you're on Facebook, ...
sempaiscuba's user avatar
  • 5,229
7 votes

Unknown 1st cousin match who shares matches with both grandparents

You're starting off with a doozy of a match. Yep, something's going on here. Let's start with the shared cM project. Looking at the total cM match only, your possibilities for a 1,193 cM match ...
Cyn's user avatar
  • 2,446
7 votes

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

DNA inheritance is very random in terms of how much DNA you get from each ancestor, due to genetic recombination. This basically means that although you get close to exactly 50% of your autosomal DNA ...
Harry V.'s user avatar
  • 18.9k
6 votes

How am I really related to a person with 1246 cMs and no shared X-DNA?

You are most likely first cousins. You are correct to say that first cousins on average share about 850 cM, but due to the randomness of genetic recombination, the range of the amount of DNA ...
Harry V.'s user avatar
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6 votes
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Why are the lengths GEDmatch.com Chromosome Segment Matching segments not proportional to their cM?

The colored segments are not drawn in terms of cM, but in million base pairs (Mbp), which are the number shown on the bottom of your graphic. The numbers at the bottom are very approximate in position....
lkessler's user avatar
  • 16.8k
6 votes

Is a half-sibling match on AncestryDNA reliable, or is more testing needed?

Just a note that you should not automatically jump to the conclusion that you and your probably-half-sibling must share a father instead of a mother; young unmarried pregnant women were often ...
Asparagirl's user avatar
  • 1,860
6 votes

Does having child of DNA tested parent help find parent's DNA ancestors?

I will try to explain more comprehensively. What does phasing do and what task does it solve? We use phasing to separate the list of matches of one's person into two smaller lists of probable ...
George Gaál's user avatar
  • 1,075
6 votes
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Does having child of DNA tested parent help find parent's DNA ancestors?

Edit: Brainstorm and I had an extended discussion through the comments on whether Visual Phasing of siblings can add information that the parent's DNA test doesn't already add. I have been convinced ...
lkessler's user avatar
  • 16.8k
6 votes
Accepted

Can my DNA results be wrong?

Unfortunately, the test can't be wrong. If it states that you have ONLY 1762 cM with this person, it means that you are in relations like uncle/niece or grandparents with their grandchild. Of course, ...
GEORG GAAL's user avatar
6 votes

Determining if 2nd cousin is father from DNA test?

A person will share roughly 3% of their DNA with a second cousin. A person shares 50% of their DNA with their father. If you have the luxury of testing the autosomal DNA of both the person and the ...
Harry V.'s user avatar
  • 18.9k
6 votes

Explaining unshared DNA segments with full sibling?

Each sibling gets half their DNA from each parent. At each pair of chromosomes, one chromosome is from their father and one is from their mother. But the siblings don't get the same parts from each ...
lkessler's user avatar
  • 16.8k
6 votes

How to narrow down the best DNA donors in a large family?

I'm going to write a more simplified and generic answer about the process of answering the question, for people who have similar problems. You list your goals as follows: Confirm paper genealogy. ...
Jan Murphy's user avatar
  • 25.7k
6 votes

Can half siblings share no common DNA?

The tests can be trusted. You are not half-sisters. Paternal half-sisters, minimally speaking, share an entire X chromosome, as females inherit one X chromosome from their father. Beyond that, they ...
Leah Worster's user avatar
6 votes
Accepted

What are the chances of having autosomal DNA from an ancestor N generations back?

This is exactly the question I answered in my blog post about 2 years ago: Probability of No Autosomal Segments Matching The final table of probabilities I came up with was: So reading the table: ...
lkessler's user avatar
  • 16.8k
6 votes

How do descendants of twins affect DNA matching?

The fact of identical twins being involved in a match has no influence of the amount of matching or nature of the relationship unless the path from one person to their match includes both identical ...
RobertShaw's user avatar
  • 3,877
5 votes
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Is a Chromosome 23 match less statistically significant for the same cM?

There is no autosomal chromosome 23. The human cell has 22 pairs of autosomal chromosomes (termed chromosomes 1 through 22). The remaining two chromosomes of the cell nucleus are the sex chromosomes,...
RobertShaw's user avatar
  • 3,877

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