Finding Your Birth Family with a DNA Test

By Diahan Southard

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Nearly 3 million US children were placed into adoption between 1945 and 1975, the only years when official government statistics exist. Formal adoptions peaked in 1970 at 175,000. (Neither figure captures informal adoptions that weren’t documented in the courts.)

Approximately 5 million Americans alive today are adopted. They have memories of Christmases and birthdays and baseball games and vacations at the lake. They’ve lived—and are still living—full lives alongside the families who raised them. But many adoptees nonetheless have a longing to know why they have green eyes and high cheekbones, and whether their family histories include diabetes or heart disease.

In increasing numbers, adoptees and the children and grandchildren of adoptees are turning to DNA testing to learn those unknown parts of their personal stories. We’ll outline the process of finding your birth family with DNA.


Step 1: Set Realistic Expectations

I had a client who tested her own DNA in hopes of finding her dad’s biological father. She found a second cousin match who led her to the right family. Genealogical sleuthing helped her form a hypothesis for the identity of her biological grandfather. After I confirmed her findings, she said, “I honestly didn’t think it would be so easy.”

Of course, it isn’t usually that easy. But your chances of finding a second cousin or closer match in autosomal DNA databases are skyrocketing as more and more people test with services like AncestryDNA, Family Tree DNA, 23andMe and MyHeritage DNA.

Before you even take a DNA test, set reasonable expectations about what you may find and how it will affect others. Like any journey of self-discovery, taking a DNA test to try to discover your biological ancestry is fraught with uncertainties. Where do you start? How will you interpret the results? Do you really want to know the real story?


Before you find that match, you must decide how the discovery will affect that person, who likely doesn’t know you exist. You need to balance your right to know with their right to not know. There are no rules on how this should work, but the general consensus among researchers experienced in birth family reunions is that as an adoptee, you have the right to know your heritage, but you don’t have the right to a relationship with your biological family.

Consider turning to loved ones or a professional for help deciding whether to embark on your search or for support along the way. You may find comfort and research guidance in the experiences of others on the same journey; try online groups such as DNAAdoption Community and Search Angels.

You might want to know just your ethnic background. But given the current composition of DNA databases—and the millions of people who have taken tests—it’s futile to think you’ll learn just your ethnicity percentages and that’s as far as it’ll go. If you truly don’t want to find your birth family, your best options are to opt of matching at your company.

Step 2: Take Your Test

To learn about your biological family, you need as large a pool of potential matches as possible. At time of writing, of the four companies providing cousin-matching, you can get into three of them for the price of one. Start by testing with AncestryDNA. When you have your results, log in to your account and use the settings menu at the top right of the DNA home page to download your raw DNA data to your computer. Then upload that data to Family Tree DNA and MyHeritage by following the instructions on their websites (for more help, see here).

If you already know one parent, try to have that known parent, or a half-sibling or cousin on that side, tested. If your DNA match also matches that known relative, you’ll know the match is related on your known side.

An autosomal DNA test isn’t the only test that can aid in your birth family search. The Y-DNA (direct male line) and mitochondrial or mtDNA (direct female line) tests are worth considering because you’ll know resulting cousin matches are related through the direct male or direct female line.

MtDNA testing probably won’t lead to major discoveries about a biological parent. MtDNA keeps a meticulous record of your direct maternal line ancestors. You have the same mtDNA as your mother, who has the same as her mother, who has the same as her mother, and so on back to ancient times. Someone who has the same mtDNA as you shares an ancestor on that maternal line, but the question of when that ancestor lived becomes an issue. An exact mtDNA match could be your mother, your sister, or your 20th cousin. There’s no good way to tell the difference.

If you’re a man searching for your birth family, your Y-DNA is far more valuable. Women, as you know, don’t have Y-DNA and can’t take this test. Y-DNA works similarly to mtDNA, except it reveals origin and match information for your paternal line. The ethnic origin information—called a haplogroup—might tell you if you’re Jewish or African or Native American, but more often than not, it’ll indicate only that your origins lie somewhere in Europe.

But your Y-DNA match list might reveal an important clue: your surname. In most cultures, the surname is passed father to son, just like Y-DNA. If your Y-DNA match list at Family Tree DNA (the only company offering full Y-DNA testing) has a bunch of guys with the surname Butler, that could be your biological father’s surname. It’ll help if you have at least 67 Y-DNA markers (or locations) tested.

Then, pay attention to the Genetic Distance column in your table of matches. The genetic distance between you and a match will be 3 or lower if you share a recent common ancestor. Because Y-DNA mutates slightly more frequently than mtDNA, it’s easier to estimate how far back a common ancestor might’ve lived.

While Y-DNA, and occasionally mtDNA, might provide important clues in your search, they’ll rarely confirm that a match is a close relative. For that, you need autosomal DNA.

Step 3: Examine Autosomal Matches

When you log in to review the results of your autosomal DNA test for the first time, your ethnicity chart may distract you with colors, maps and percentages. These are alluring, especially if you’ve never had any indication where you’re from. With one click of a mouse you go from drifting in a sea of possibilities, to dropping anchor in the Baltic Sea or the English Channel. Keep in mind, though, that these percentages aren’t always accurate and can vary depending on the testing company.

To identify close biological relatives, turn to your list of matches—other test-takers who have some of the same DNA you do. Follow these three steps:

1. Look for a second cousin or closer match.

Matches are ranked starting with the closest, and the website predicts a relationship (such as sibling or third-to-fifth cousin) for each one. You might find a parent or sibling on your match list, making things simple. Otherwise, you want a second cousin or closer match. You can go through the process with more-distant cousins, but it’ll be significantly more complicated and time-intensive.

2. Check your match’s pedigree chart for a common ancestor.

For example, second cousins share great-grandparents, so you’ll know that one of your match’s four sets of great-grandparents also are your great-grandparents.

This can be trickier than it sounds. Your testing company estimates your relationship based on the amount of DNA you share, measured in centimorgans (cM). But due to the random nature of DNA inheritance, a given relationship can have varying amounts of shared DNA. For example, relatives who share 250 cM could be second cousins, first cousins twice removed, or some other genetically equivalent relationship. To determine your actual relationship, compare the number of shared centimorgans to a table like the one here, which shows ranges of shared centimorgans for known relatives who’ve tested their DNA. Our free Relationship Chart also shows the average amount of shared DNA for different types of relatives.

Keep in mind that if you’re much older or younger than your match, you could be a “removed” relative. For example, if you’re 68 and your match is 28 (which you might be able to guess from a picture or from the birth years of her parents or grandparents), then you’re likely once removed. This means you’re a generation closer to your shared ancestors than she is, and you’ll need to look a generation further back in her pedigree chart for the common ancestor.

For example, if you share 500 cM with Amber, and the table indicates you’re first cousins once removed (1C1R), instead of looking at Amber’s two sets of grandparents (as you would for a first cousin), you’d evaluate her four sets of great-grandparents.

You could perform this same process for a third cousin, but instead of having four sets of great-grandparents to evaluate, you’d have eight sets of great-great-grandparents, making the process more difficult. If your match doesn’t have a pedigree chart posted, you may need to message him or her to ask for a tree, which can raise some touchy issues.

3. Narrow your common ancestor candidates to the one connecting you.

A good way to figure out which grandparent or great-grandparent couple you share with your match is through triangulation, using the Shared Matches or “in common with” tool. Your match list might contain just one second cousin, but it likely lists third or fourth cousin matches who are also related to one of the four sets of great-grandparents.

The shared matches tool finds your matches who share DNA with both you and your second cousin match. You can then look through the pedigree charts of those shared matches for evidence of a connection to one of the candidate great-grandparent couples.

For example, say you have a second cousin match JSBrown68. You write down the names of his great-grandparents, and one couple is Mary Ann Waterton and Wesley Hall. When you look at the DNA matches you and JSBrown68 have in common, one has an online tree with Halls in it. Another has Watertons in his tree. This is a clue that Mary and Wesley are your great-grandparents. The July/August 2017 Family Tree Magazine can help you use this type of triangulation analysis to determine how you’re related to your matches.

4. Research forward in time.

Once you’ve identified your ancestral couple, it’s time to research in genealogical records. You want to identify all of Mary and Wesley’s grandchildren and determine where they were about nine months prior to the date you were born.

Step 4: Put it Together

So the process is simple: Find a second cousin or closer match, determine which generation has your connection, use shared matches to identify a possible ancestral couple, then research their descendants. My mom was adopted as an infant, and our search for her birth family shows how you can leverage your DNA match list to find your ancestors.

After having mostly fourth cousins show up on her match page, Mom and I were thrilled when we saw June, a “first-to-second cousin” match at Family Tree DNA. If June (who gave her OK to share this story) were a first cousin, she and my mom would have the same grandparents and mom’s father would be June’s uncle. (Because of other research, we were pretty sure June was on Mom’s paternal side.) If June were a second cousin, she and Mom would share a set of great-grandparents. This was before the Shared cM Project began, or we would’ve been able to see right away in its table that June and my mom were very likely second cousins.

June didn’t have a pedigree online, so we contacted her (see the box on the opposite page). After consulting with her relatives, she sent us some family information. Other members of her family also had tested. By studying the family tree data and comparing the matches Mom and June shared, we determined that my mom and June were second cousins and identified their common great-grandparents. Mom’s father was one of their grandsons.

Next, we researched genealogical records to identify all the couple’s grandchildren and theorize, based on their locations around the time of Mom’s birth, which grandson was the most likely candidate to be my mom’s father. Patience was key: The great-grandparents had 13 children and around 130 grandchildren to track down. We did ultimately identify the right grandson and Mom is in touch with her birth family.

Be prepared for bumps along the way. As you can see, this process is dependent on other people. You need a second cousin to take a DNA test. You need him to link his results to a pedigree chart and/or to communicate with you. Then, if you can locate close relatives, you may need answers your questions about your birth family.

The more I do genealogy, the more I notice the magical power of timing. Just because you looked for that court record today and didn’t find it, doesn’t mean it won’t be there tomorrow. While it might seem like anyone who gets a DNA test must be interested in finding cousins, that’s not the case. People test for different reasons—curiosity about ethnicity, a short-lived interest in genealogy, a gifted test—and sometimes you have to be patient when waiting for a second cousin to show up or for a response to your contact.

Whatever the outcome, your DNA testing experience will change how you see yourself and your family. It may draw you closer to each other or push you apart, depending in part on your attitude and perspective. You might or might not find what you hoped for. The journey is filled with twists and turns, and it’s up to you to decide whether you want to take it.

A version of this article appeared in the December 2017 issue of Family Tree Magazine.