GEDmatch and DNA Testing 101

Hello and welcome to my GEDmatch and DNA Testing 101 class.

My background is in biochemistry. I've changed the DNA of things before. I'm still not an expert, but I believe I know enough to help YOU.

I know how to use GEDmatch for the purpose of finding birthrelatives and that's all you really need. While there are other blogs and video tutorials that walk you through how to use GEDmatch or understand DNA results, I (a biochemist) get completely lost and confused. So I decided to make my own tutorial (just as much a reference for me as it is for you.)

What is DNA?

Read this article by Khan Academy. But I'll to break it down for you here. DNA stands for "deoxyribonucleic acid." It holds all the instructions in your body for making YOU! It is a polymer. (Poly = many) Think of a polymer as a beaded necklace. Each bead is a monomer (Mono = one). In this case, the monomers are four nucleotides (A, G, C, T). When your DNA is "sequenced," the order of the nucleotides is determined.

Chromosomes are made from two strands of DNA polymers twined around each other in the double helix shape.

Humans have 46 chromosomes. That means 23 pairs of chromosomes. (Hence, the name in 23andMe). Segments of a chromosome are called "genes." Of your 23 pairs of chromosomes: you have 22 pairs of autosomal chromosomes and 1 pair of sex chromosomes. Sex chromosomes determine your sex: XX for females and XY for males. 

What is an Automsomal vs. Non-Autosomal vs. SNP DNA Test?

When you get an autosomal DNA test (23andMe is an autosomal DNA test), you are able to determine relationships like mom, dad, cousins, aunts, uncles, and siblings. This is because your entire DNA is sequenced.

If you do NOT do an autosomal DNA test, then you will only be able to find your mom or dad or children...a first cousin, sibling, or aunt match will simply not be possible. This is why taking an autosomal DNA test is so important: matching with a sister, for instance, would help you find your birthparents. (At the moment, My TapRoot uses an Allele Test, which is NOT an autosomal DNA test.)

Beware of SNP-only testing as these usually give false positive results. SNP stands for "single nucleotide polymorphisms." Instead of sequencing the entire DNA, they look for certain markers. Using an algorithm (fancy math), they can make their best guess as to whether you are really related to someone else or not...but it is NOT as accurate as an autosomal DNA test, where every chromosome is sequenced. By doing an SNP test, you run a high risk of "matching" with siblings who have absolutely no relation to you. In other words, a false match.

What percentage of DNA is inherited from your birthfamily?

YOU have DNA that is inherited from your parents. Your birthmom gave you 50% and your birthdad gave you 50%. The same is true of them. Your birthmom inherited 50% from your grandmother and 50% from your grandfather.

In this way, math can figure out your relationship with your DNA relatives. It isn't perfect though and more variables are introduced the further out you go. For instance, half-siblings or removed cousins (different generations) can introduce some uncertainty in what the percent DNA shared really means. That's why you will typically see a range: "3rd to distant cousin."

Where should Chinese adoptees put their DNA? 23andMe and GEDmatch.

The best way to find blood relatives is to pool all our resources and use a single database. By far, 23andMe is the unofficial database of Chinese adoptees. You have the best shot at finding other blood relatives, such as other adopted siblings, on 23andMe.

Why should you use GEDmatch? Because GEDmatch is a mega DNA database that is free to use. If you did your DNA through 23andMe, Ancestry, or any other service, you will be able to upload it to GEDmatch. 

For Chinese adoptees, it is crucial for you to upload your DNA to GEDmatch because DNAConnect.Org puts all the DNA from birthfamilies into this database. So far, 69 adoptees have found their birthfamilies thanks to DNAConnect. 

Be extremely cautious of services that seem to target (not serve) the Chinese adoptee community or things that seem "too good to be true." For instance, Zuyuan is NOT a safe option for adoptees to put their DNA into. While it may sound good that a certain organization has "ties" to a Chinese database, it is well known that all Chinese DNA organizations are government-sanctioned. Be wary. Do your research. It is ultimately your decision--so make an informed decision. Hint: Facebook Search Groups are rife with misinformation. Be careful.

GEDmatch Tutorial Begins

Part 1: Setting Up the GEDmatch Account from 23andMe

First, you need to do a DNA test with a company, like 23andMe.

Then, you have to download your raw DNA data file. On 23andMe, simply go to the search box and type in "download." The feature to "Download Your Raw Data" should pop up. Click it. After this you will need to download your raw data file. It will be in a zip folder when you download it. KEEP it in the zipfolder.

screenshot from 23andMe

Go to GEDmatch and create an account. You need to upload your raw DNA in the zip folder still! Save your login information, including your kit number. This is very important!

Now you're in. So I guess you want to find out if you have any relatives, huh?

Part 2: Using GEDmatch to Find Relatives

There are two ways to access the "one-to-many DNA Comparison Result" feature. One is by clicking on that feature in the right-hand menu, but then it prompts you to type in your kit number and that's a pain in the ass to look up all the time. The easier way is to simply click your kit number in the box as shown in the screenshot below:

Ta-da! Now, you've reached the gigantic spreadsheet of your "relatives." Because many DNA researchers use GEDmatch, there are features here that are not as relevant to you and are more complicated to use. For your purposes, mainly pay attention to the seventh "Gen" column.

Here are the column titles:

1. Kit is their GEDmatch kit number. If you click this, you see their spreadsheet.
2. 1:1 is very complicated. I never use it.
3. Name typically, people use an alias in the name entry, but if they actually indicated an alias name as a fake name, there will be a star * in front of their alias
4. Email emails that end in qq.com, 163.com, or sina.com (typically) originate from China. Before you get your hopes up though, recognize that many false matches occur with Chinese DNA testing companies that typically do non-autosomal DNA tests. DNAConnect.org@gmail.com means it is a birthfamily looking for their child. ONLY contact them IF your gen number is under 3. (read below)
5. Largest Segment the length in centimorgans (cM) of the largest DNA segment your kit shares with their kit. Closer relatives have larger numbers.
6. Total cM if you added up the lengths in centimorgans of all shared DNA segments. Closer relatives have larger numbers.
7. Gen this is important!
   Key:
   Twins and Parents = 1.0
   Aunts/Uncles/Grandparents = 1.5
   First cousins = 2.0
   If Gen is <3 and is a DNAConnect.org kit, you may contact them for help
   If Gen = 4.0 to 4.5 it becomes less accurate, can translate as "distant cousins"
   Some numbers are in-between the numbers listed, which means that there are a few possibilities and the algorithm isn't sure. Smaller numbers are closer relatives!
8. Overlap Basically, more overlap means a closer relative. Very low overlap will not be shown. Low overlap will be indicated with a red background. More overlap will appear with a whiter background.
9. Date Compared just tells you when their kit was determined to match to yours, so you could keep track of more recent vs. older discoveries.
10. Testing Company This is a self-reported column, so it may not be incredibly accurate. This is the DNA testing company they claim to have used. WeGene, 23Mofang (MF), and GeseDNA (GESE) are Chinese DNA companies. There was a PSA sent out in the past about false matches occurring with Chinese DNA kits, so be careful. If you end up emailing someone and it seems like a scam, it probably is. If it says "migration" that just means the kit was around when GEDmatch was younger. As GEDmatch goes through updates, kits need to be moved to the newer versions. DNAConnect puts "DNAConnect" in the testing column.

How do you contact people?

Again, be cautious and respectful. People do not want to be spammed, so if you do write an email, make sure to put 1) their kit number (column 1) and 2) YOUR kit number, and let them know your relation to them: how closely are you related? What does your gen column say?

Many people manage multiple DNA kits so it is important to put the kit information for them to easily look you up. Be prepared for people to not respond or simply not be as open as you believe. But sometimes, you might find someone cool. I found Vietnamese relatives this way and got to Skype them!

Further reading on my blog: The Emotional Toll of Searching (and why I support DNA Connect)

Post from Research China Org: Is Zuyuan a Viable Option for DNA Birthparent Searching? TLDR: No.