For those entering the wonderful world of DNA Genealogy there are a bewildering array of different companies with unshared databases so testing with one means that you may be missing connecting with potential matches because they have tested with a different company.
This article is reproduced from that website.
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What is GEDmatch.com?
GEDmatch is a FREE, non-profit, “do-it-yourself” genomics website that allows DNA testers to upload raw data from FTDNA and from 23andMe to compare with a large database of data that has been voluntarily uploaded by other testers.
A description of the types of comparisons will follow. GEDmatch uses a slightly different algorithm for the comparison so some additional matches may be available, as well as some different views of the comparisons. This can also help provide contact information for some matches. Everyone should take advantage of this opportunity. GEDmatch is not affiliated with any of the testing companies.
The http://GEDmatch.Com site provides tools for making ‘deep’ comparisons between genealogies and DNA test results to help identify possible hidden ancestral connections with distant cousins. This is particularly useful when your GEDCOM or list of DNA matches contains hundreds, or even thousands of individuals. This service is provided free to anybody.
Upload your Raw Data
To upload your raw data and become a part of GEDmatch, you will need to go to the following websites: The instructions are pretty self-explanatory:
For FTNDA uploads:
and also please upload your X data from FTDNA:
For 23andMe uploads:
When downloading your data from FTDNA or 23andMe, if your un-zip utility, or some other program tries to open the program, it is important that you try to save the file without opening it, un-zipping it, or altering it in any way. Do not rename the file.
On the upload page there are a few questions that you want to be assured are answered:
If you change your page orientation to landscape, you have a better chance of getting the type big enough to read.
Alias (optional) – some people (for whatever reason) prefer not to show their full actual name. For an adoptee this may defeat the purpose. BUT if your name currently has no association with your birth family, this may also discourage some people from contacting you. IF you have any reference to a birth name you might want to consider adding it in some form, i.e., a middle name. My name on GEDmatch as well as my DNA accounts at FTDNA and 23andMe includes my birth mother’s maiden name as my middle name. Or, you can just leave this blank and the name you entered in Name of Donor will be the one that shows.
Haplogroups – if you know your mtDNA and/or Y-DNA haplogroup you can enter it here, otherwise leave it blank.
Please acknowledge that you authorize this data to be made available for comparisons in our public database: (You will not be able to make comparisons if it is not in the public database) – Answer this question with a resounding “YES”! This is IMPORTANT because otherwise you will not be visible in the database.
Can we provide your email address? Again, answer “YES” otherwise your matches will not know how to contact you.
The uploads will take about 24 hours to appear. If you uploaded from FTNDA, your kit # will begin with an “F” followed by your kit # at FTDNA, ie. F204903. If you upload from 23andMe your kit # will start with an “M” followed by 6 digits that are newly assigned. On the upload page for the 23andMe upload, PLEASE NOTE THE KIT # ASSIGNED to your account.
Once you have your raw data uploaded to GEDmatch, you will be able to see all your matches to people who have voluntarily uploaded their data from FTDNA, 23andMe, National Geographic and possibly other labs who have processed DNA tests. You may also see kit numbers that begin with “PF”. These are phased kits which we’ll get into later.
Utilities for use with DNA test results
On the homepage of GEDmatch is a listing of utilities – “Utilities for use with DNA test ReSULTS”
Compare your FTDNA or 23andMe results with all raw DNA results in our public database
Once your data has populated the database, click on the first utility. “Compare your FTDNA or 23andMe results with all raw DNA results in our public database”
The next page that will appear is:
Enter your kit # and click on:
The next page will take a few moments to load and will look like this:
When it’s finished loading you will have a long list of your DNA matches starting with your closest match. The estimated generations to a common ancestor are listed in the column “Gen” under “Autosomal”. But please be aware that GEDmatch’s algorithm in determining this is quite liberal. If you have a match at 4 generations, more than likely, it’s 6 generations.
First, let’s take each column in the match listing and we will explain what it is and later on tell you how to use it.
Kit Nbr – I think this is pretty obvious – your matches’ GEDmatch kit number.
Type – this is the type of DNA test and/or chip used in testing the raw data.
Triangulate – see the section on “Triangulation”, page 16.
Gedcom – this tells us if there is a gedcom uploaded to this match.
List – this link will take you to the matches for that particular kit number.
Select – a check box to use when you wish to compare chromosomes for more than 2 individuals.
Sex – Male or Female match. This could be important when a male has X matches because we then know that the connection must be through his mother, as males only receive their X DNA from their mother.
The next set are under the Autosomal heading:
Details – “A” – this link will take you to a page that shows you where exactly (on which chromosome, location and length) you match this person. It will be similar to the chromosome browser at FTDNA or the IBDData.csv that you can download from “Family Inheritance: Advanced” at 23andMe.
Total cMs – this shows you the total centimorgans of your match.
Largest cM – this shows you the longest length of centimorgans on one specific chromosome.
(We loosely define CentiMorgans (cMs) as a unit of measurement, and for our purposes can be considered a unit for measuring genetic linkage. cM is a linear relationship but not strictly inches or centimeters. First you have base pairs – each is a single position on your DNA strand. CentiMorgans has to do with how likely a particular position is to recombine. Gaye’s analogy is mile markers vs. exits. CentiMorgans are exits on some stretches of road (chromosome) they are close together (base pairs = mile markers) and on other stretches of road they are far apart.)
Gen – the number of estimated generations going back to a common ancestor for you and your match (again, we must stress that the speculation at GEDmatch may be too generous).
Under the X chromosome heading:
Details – “X” – this link will take you to a page that shows you exactly where on the X chromosome (location and length) you match this person.
Adj. cM – this is really just GEDmatch’s guess because the X chromosome is inherited and passed down differently. Females inherit their X from both their mother and father; males inherit their X from their mother’s only.
Total cMs – this shows you the total centimorgans of your X match.
Largest cM – this shows you the longest length of centimorgans on the X chromosome
Email – the email address of your match.
Comparing just 2 GEDmatch kits
The 3rd item in the list of “Utilities for use with DNA test results” can be useful when you want to compare just two kits. Example: Let’s say you find two matches who both have overlaps with you on one chromosome. But you need to find out if these two matches match each other. Our major goal being -find your matches at FTDNA, 23andMe or Gedmatch, see where there are segment overlaps with other matches, analyze the other matches to see it they match each other, and if so = common ancestor for all.
Click on this utility and a page will come up where you can enter two different kit numbers to compare:
Minimum segment cM size – You can leave it blank or we can also change/reduce/increase the Minimum segment cM size to whatever you would like. But please be aware that anything under the default value is very tenuous and may not be “real”. Caution should be taken when lowing ANY thresholds established. We are looking for good, IBD (identical by descent), real matches, not just any match.
A smaller number, under 5 will show all the matches with a minimum of 5cMs. By doing this you can assure yourself these two people do or do not match each other. If they do match and since they both match you, this will be two matches that you will want to investigate further. In conjunction with this, we can use one other utility on the homepage of GEDmatch (#4 in the list of utilities) –
Show results that match on a given chromosome segment
Let’s say you have three people who match you and match each other on chromosome 6 at location 159,862,281 to 170,224,848. By entering in this data into the “Show results that match on a given chromosome segment” we may be able to find others in your match list who also have overlaps at this location.
When entering the data in the Segment Start and Segment End remove the commas and I also expand the length of the segment. So if the Segment Start is actually 159862281, I change that to 139562281. The Segment End is actually 170224848, I expand it to 190224848. This allows for possible additional overlaps on either side of the segment.
My own results on this location show me 19 people (including my son and brother) who have matching segments at this location.
Here’s the partial list (the last one, with the very long segment match, is my brother):
We then need to go back to “Comparing just 2 GEDmatch kits” to see if any of these people who match you, also match each other.
We may be able to simplify this process by using the triangulation utility at GEDmatch. Unfortunately for those of us with unknown ancestors or no other known relatives it can be a futile process. We are usually better off using those matches we find at FTDNA or 23andMe who are ICWs. If you already know a confirmed relative and they also are on Gedmatch, it may help you distinguish between maternal and paternal matches. For example: If you know your birth mother, and have tested her or one of her genetic ancestors/descendants, anyone who matches both you and her theoretically should be from her ancestral line. If that particular match doesn’t match her, you can assume that the match is from your paternal line. You can go through each page of the triangulation list looking for yourself and see who that match is. Then see if or where the segments might be and if there is an overlap. If there is, we can possibly assume there might be a common ancestor.
Essentially, the triangulation utility lists your matches and sees who they also match.
Triangulation in DNA analysis allows us to compare our matches with their matches and help us determine a possible relationship with another person. It may even help us in determining if the relationship is paternal or maternal. As adoptees or others with unknown ancestry, especially without any surnames, and when we have NO IDEA of either our maternal or paternal ancestors the challenge can sometimes be overwhelming.
Let’s assume that several of your DNA matches seem to fit to an ancestor that could possibly also be yours. You’ve communicated with some, have found gedcoms and worked a family tree for this family, so you have several if not many other surnames. The triangulation utility may help find others who might also fit into this family by noting common surnames, by comparing ICWs (also a form of triangulation) and finding overlaps. Thus, continuing to expand this tree and ultimately find YOUR place in this family. Doing triangulation is even more helpful when you have a larger pool of known relatives for which to compare results.
In order to do triangulation at Gedmatch you must first Upload your FTDNA FF (Family Finder) match results file (currently disabled). It is listed on the homepage of GEDmatch (http://www.GEDmatch.com), under UPLOAD YOUR DATA FILES.
To access your FF match results file for upload, go to your matches list at FTDNA. At the bottom of the list, under the page numbers, you will see, Download Matches. Click on CSV:
Page: 1 2 3 4 5 6 7 8 9 10 … of 31
This will download a file that looks like: 291080_Family Finder_Matches_20120922.csv. Save it to a folder or directory that you will remember.
Go to the Upload your FTDNA FF match results link on http://www.GEDmatch.com and follow the instructions to upload this file.
For 23andMe testers, the file to upload will be your Ancestry Finder file which can be found at your 23andMe account. Once you’ve logged in, go to the Ancestry Labs link (https://www.23andme.com/you/labs/ancestry/), then the Ancestry Finder (https://www.23andme.com/you/labs/ancestry_finder/) link.
At the bottom of the page will be a link to download your Ancestry Finder matches:
Top of Form
Bottom of Form
Reminder: If you’ve made your name visible to all 23andMe me
The file name will be ancestry_finder_YOUR NAME_DATE.csv. Save it to a folder or directory that you will remember.
Go to the Upload your 23andMe Ancestry Finder file link on http://www.GEDmatch.com and follow the instructions to upload this file.
Once the information is populated into the database, a “T” will appear next to your matches on the GEDmatch match list page.
Other Utilities at GEDmatch:
Just a quick word on Admix/Population Finder analysis. Currently the algorithms and analysis for determining your ethnicity have been found to be less than reliable and sometimes just plain wrong. If you believe that this will help you in determining your ancestry, we can certainly direct you to those knowledgeable on this subject. Just ask!
PHASING YOUR DATA
“Phasing” refers to the process of separating the mixed DNA results into the DNA obtained from your mother and the DNA obtained from your father. This is typically done by comparing your results to your parents’ results and determining which parent could have and/or must have contributed each SNP.
Phasing your data requires that both parents and a child have been tested and all their data has been uploaded to GEDmatch. For adoptees who have yet to identify their birth families, this obviously cannot be done. New technologies are being discovered every day though, and hopefully phasing of siblings may soon be available.
GEDCOMS on GEDMATCH
Gedcoms can be most helpful in trying to sort out your matches and building those family trees.
The GCU (Gedcom Comparison Utility) can be used to help automate some of the functions in the methodology.
The website http://www.DNAGedcom.com contains an interface of the GCU utilities available.
A word on CSV files:
Csv files are totally text files. When saving for continued use and updating, we recommend saving them as Excel worksheets (.xls or .xlsx files). This prevents the loss of formatting and Excel spreadsheets give you many more options to work with.
We will add additional information here as to how to further use the GEDmatch utilities as they become available and we will inform all on the AdoptionDNA and AdoptionDNA_Tools lists.
You can help us all and the GEDmatch innovators by donating to their fund.