How 23andMe identifies your DNA Relatives

Scientific Details

Learn about your DNA Relatives, the diverse group of 23andMe customers who have DNA in common with you. Only individuals who have chosen to participate in DNA Relatives are the subject of this report.

How 23andMe identifies your DNA Relatives

To identify your DNA Relatives, we use an algorithm that finds segments of your DNA that are identical to DNA segments of other 23andMe customers. When these segments are sufficiently long, we infer that they were inherited from a recent common ancestor. These segments are known as “identical by descent,” or IBD. Our algorithm searches for these matches across virtually your entire genome, so we can identify DNA Relatives on any branch of your family tree.

Note: IBD/Half IBD:

The comparison results in this feature displays shared segments of DNA on separate lines representing each chromosome pair, and labels the shared segments as Half IBD, or identical by descent. Because you inherit one half of your DNA from your mother and the other half from your father, IBD segments typically occur on only a single chromosome. Half IBD refers to the amount of the genome in centiMorgans (cM) that contains an IBD segment on either chromosome. The percent DNA shared in DNA Relatives is based on this number.

Your half IBD and shared segments vary based on the closeness of your relationship with the matches with whom you are comparing. Closer relatives will share thousands of cM and many segments in common; more distant relatives may share only one. For some of your shares, if you connected outside of DNA Relatives, you may not share any segments at all.

Every time DNA is passed from one generation to the next, the two chromosomes in each pair are randomly shuffled with each other in a process called recombination. Then, only half of this new DNA — one set of chromosomes — is passed down to each child. The total amount of DNA passed down from an ancestor is cut approximately in half each generation. Through this process, long inherited segments are broken up generation by generation into multiple shorter ones and sometimes lost altogether.

Despite all of this generational shuffling, DNA Relatives is highly sensitive and can pick up matches ranging from siblings and uncles to distant eighth cousins — individuals that share great-great-great-great-great-great-great grandparents with you. It may not always be obvious how you share a connection with someone, but that’s where our DNA Relatives tool comes in. Visit the tool to find out more about your matches and get in touch to learn about your family history.

See our Customer Care pages for more information:

Shared segments between cousins

Inheritance family tree graphic.

A closer look at the matching segment

An example graphic showing a matching segment between you and your cousin.

Sources of information used in this report

The Your DNA Family report provides aggregated summaries of several attributes of your DNA Relatives. The following information sources are used in the report:

Report Section
Close to distant DNA Relatives

Computed IBD results from the DNA Relatives tool.

Locations of your DNA Relatives

Answers to survey questions by your DNA Relatives.

Ancestries of your DNA Relatives

Computed results from the Ancestry Composition report.

Traits and behaviors in your 23andMe DNA Family

Answers to survey questions by your DNA Relatives.

Traits in Your DNA Family

Discover Your Roots with DNA

Source: DNA Testing Advisor ( Access on May 18, 2017

Discover Your Roots
with an African DNA Test

African Outline

Many African Americans and others are using an African DNA test to get answers about their ethnic ancestry.

Typical questions include the following:

  • How much of my genetic heritage is African?
  • What regions of Africa do my ancestors come from?
  • Where does the remainder of my heritage come from?
  • Is my African ancestry from my father’s lineage or my mother’s?
  • Do my physical features reflect African ancestry or something else?

Fortunately, there are several reasonably-priced African DNA tests that answer these and other questions about one’s ethnic ancestry.

The tests all use home test kits and sample collection is easy and painless. Depending on which company you use, you might wipe some cells from inside your cheek with a little swab or spit some saliva into a tube. No blood is required.

Here are my top seven recommendations for anyone interested in an African DNA test.

1. Ancestry DNA

AncestryDNA recently rose to the top of this list. Both men and women can take the test and it will identify other people in the database who share common ancestors with you. It is an autosomal test similar in technology to Family Finder and 23andMe, discussed below.

The test includes an Ethnicity Estimate that summarizes the percentage contributions of different regions of the world to your overall ancestry. That estimate now breaks African Ancestry into nine regions:

  • Africa North
  • Senegal
  • Ivory Coast / Ghana
  • Benin / Togo
  • Cameroon / Congo
  • Mali
  • Nigeria
  • Africa Southeast Bantu
  • Africa South-Central Hunter-Gatherers

This is the first widely recognized, legitimate DNA test to provide this detailed a breakdown of African ancestry

2. Family Finder, which includes Population Finder

Family Finder is an autosomal DNA test from Family Tree DNA. It’s widely used by genealogists, including those interested in African American genealogy.

The company will compare your DNA against a database of other users to find genetic matches. Most often these genetic matches will be cousins, having a common ancestor with you somewhere in the last five or so generations.

By emailing your matches you can connect with previously unknown relatives and learn much more about your family tree.

As part of the Family Finder test, you receive a myOrigins report, formerly called Population Finder, where the company compares your DNA with over 60 reference populations from around the world. This is a biogeographical analysis of the DNA you received from ALL of your ancestors.

The African part of your DNA may place you in any of four sub continental groups based on similarities to certain scientifically studied populations. The groups and populations are as follows:

  • Central African: Biaka Pygmy, Mbuti Pygmy
  • East African: Bantu (Kenya)
  • Southern African: Bantu (South Africa), San
  • West African: Mandenka, Yoruba

Very few people outside Africa are 100% African. Population Finder will classify the remaining portion of your ancestry using other populations.

3. Y-DNA Test at Family Tree DNA

Family Tree DNA also offers a Y-DNA test, which tracks your paternal line. Since only men have a Y-chromosome, only men can take this test. But women can still test a man from their paternal line, e.g. a brother, a father, a brother of your father, or a son of your father’s brother.

Like Family Finder, this test finds genetic matches who share a common ancestor. But with the Y-DNA test you know the common ancestor has to be a male in the direct paternal line like your father’s father’s father etc.

The Y-DNA test will also predict a man’s Y-DNA haplogroup. And many haplogroups are clearly tied to origins in sub-Saharan Africa. This is the real indicator of your paternal line’s ethnic ancestry.

TIP: If you’re interested in finding genetic matches, you should order the Y-DNA 37 test, which checks 37 markers. But if you’re only interested in determining your haplogroup, you only need 12 markers. I suggest you go to Family Tree DNA and look for the combination package of Family Finder plus Y-DNA 12. The combo price is an excellent buy.

If you later decide that you want to discover your precise position in the Y-DNA tree of life, you can upgrade to more markers or even order a Deep Clade test. That will tell you exactly which subclade of your haplogroup you’re in. In many cases this can tighten the geographic origins of your paternal line.

4. mtDNA Test at Family Tree DNA

Both men and women have mitochondrial DNA (mtDNA) to test. But only women pass it on to their children. So mtDNA is the test to track your maternal line. That’s your mother’s mother’s mother etc.

As with the test described previously, you will probably see matches with other users. But mtDNA mutates so slowly that your common ancestors may have lived thousands of years ago. That makes mtDNA less useful than Y-DNA as a genealogy tool.

Still, mtDNA also has a haplogroup that relates directly to the origins of your maternal line. And some of those are clear indicators of African origin.

5. 23andMe Which Includes Ancestry Composition

23andMe is another autosomal DNA test like Family Finder. This test can also serve as an African DNA test, because it has an Ancestry Composition feature that tells you what parts of the world your ancestors lived a few hundred years ago.

This admixture report is similar to the Population Finder feature of the Family Finder test. It reports on African Ancestry from these three regions:

  • West African
  • East African
  • Central and South African

However, if you also test at least one of your parents on 23andMe, this test can split your ancestral percentages into your paternal and maternal sides.

23andMe also has a DNA Relatives feature that’s similar to Family Finder and it will estimate your Y-DNA and mtDNA haplogroups. So if you want to cover all your bases—then the 23andMe test can be a great value as an African DNA test.

6. Y-DNA and mtDNA Testing at African DNA

Harvard University Professor Henry Louis Gates, Jr. was a pioneer in African DNA testing. He founded African DNA to encourage more African Americans to get their DNA tested.

The company offers a Y-DNA test of 25 markers and an mtDNA test like the mtDNA Plus test at Family Tree DNA. In fact, Family Tree DNA is affiliated with the company and does their DNA testing.

Now they can also offer the Family Finder test that they renamed Ancestry Finder.

Note that African DNA only offers one paternal line Y-DNA test and one maternal line mtDNA test. They do not offer additional Y-DNA markers, the Full Mitochondrial Sequence (FMS) test, or Deep Clade testing. You need to order those tests directly from Family Tree DNA.

The African DNA web site does have more content specific to African DNA testing than any of the more general DNA testing companies. So I encourage anyone looking for an African DNA test to visit the site and learn all you can.

Uniquely, African DNA does offer some higher priced packages that combine DNA testing with genealogy research to build your family tree.

For most African-Americans there are no genealogical records prior to the 1870 census, when last names of former slaves began to be recorded. If you want someone to build a few generations of your family tree, however, this is an option to consider.

MONEY-SAVING TIP: If you’re not ordering a package with genealogy research, be sure to recheck Family Tree DNA to compare prices before placing an order with African DNA. At the time of this writing, you can order the same Y-DNA and mtDNA tests directly through Family Tree DNA for significantly less money.

7. Y-DNA and mtDNA Testing at African Ancestry

African Ancestry is another company that specifically features African DNA tests. Like the companies above, they check your Y-DNA and mtDNA to determine your paternal and maternal lineages. Since their web site does not provide details of either test, I cannot compare them.

Unlike Family Tree DNA, they do not keep a database of customer results, so you will not receive any matches to people with similar DNA. Since the company does not have an autosomal test like Family Finder and 23andMe, it cannot provide any admixture percentages. You won’t learn anything about ancestors outside your narrow paternal and maternal lines.

I found some interesting data on the web site. Even though this site specifically attracts people of African descent, 35% of the paternal line tests show European ancestry. Much of that non-African DNA was introduced into the family tree during the era of slavery. In addition, 8% of their maternal line samples show non-African haplogroups.

An article in the Wall Street Journal was critical of the African DNA test reports provided by this company. Independent experts say that mitochondrial DNA is not sufficient to nail down an ancestor’s origin to a specific country.

Furthermore, the large migrations of Africans over the last 3,000 years means that the typical black American’s DNA will match Africans living today in several countries. Even the founder of African DNA was quoted in the article that the country-specific reports his company provides are largely a “best guess.”

The testing prices at African DNA are higher than those of the companies listed above. Even if you have your African DNA test done elsewhere, the African Ancestry web site includes some interesting information on African heritage and a list of country-by-country resources in Africa for genealogists.

Other African DNA Tests of Uncertain Quality

DNA Tribes uses autosomal markers representing all your ancestors. But unlike AncestryDNA, Family Finder and 23andMe, which check nearly a million autosomal SNPs, DNA Tribes checks a maximum of 27 STRs.

I won’t try to explain the difference between an STR and a SNP here. But autosomal STRs are what police forces around the world have been collecting from criminals for decades.

The company examined 383,000 STR records and claims to have identified major genetic regions around the world. They compare your DNA with their proprietary database and issue reports on your most closely matched regions.

The company does not share its database or reveal its methods. And independent experts are skeptical when such detailed reports arise from so few markers.

Roots for Real offers Y-DNA, mtDNA, and an autosomal test based on 16 STR markers. They position their autosomal admixture test as an African DNA test. But their database is only about one third the size of the already questionable DNA Tribes test. And all of their tests are overpriced compared to market leaders Family Tree DNA, 23andMe, and


The National Genographic Project Genetic Markers



Dr. Spencer Wells, explains how genetic markers can be used to build a family tree for everyone alive today.


Resource: The Nstional Geongraphic “The National Genographic Project, accessed May 1, 2017,


Genetic Genealogy For Beginners – Discovery your Family History Through DNA 101




This course as the first one “Genetic Genealogy For Beginners” is an expansion and goes a little more deeper into the DNA with some additional learning tools. In these lessons rather than chapter we will use Genetic Genealogy, Molecular Genealogy (the field of biology that studies the structure and function at the molecular level and thus employs methods of both molecular biology and genetics. The study of chromosomes and genes expression of an organism.) Sounds intimidating but it will be broken into manageable understandable lessons. There is a test after each lessons to help you gain a solid background before moving to Intermediate and Advance Genetic Genealogy. This will be a four week course and starts May 1 – May 26 2017.

mark you calendar for this course.

Genetic Genealogy for Beginners – Chapter 3



Y-DNA Explained

Almost every article I have read on Genetic Genealogy, there have been comments or reviews from readers stating their frustration and confusion understanding the literature by well intended authors.

This chapter will began to focus on Y-DNA testing, which is the oldest test. Before we get started, lets look at your goals for testing to make sure you are clear. I suggest you write out your goals.

Do you have a general idea or just a curiosity about genetic genealogy or is your focus more specific? Consider the following questions:

  • Are you primarily interested in researching your surname?
  • Are there specific brick walls (you feel you can not  research further) that you wish to target with the use of DNA testing. (African-American getting beyond 1860)
  • How far back in your family tree are these brick walls? (This is a serious question for African-American genealogy researchers.)
  • What is the ancestral pattern back to these walls, i.e. – mother’s mother’s mother’s, mother or father’s mother’s mother’s father’s, father’s father’s father?
  • Are you ready for a long-time project or do you desire quick answers? (Long-time projects are best suited for this type of work. Quick answers tend to create mistake after mistake.)
  • Are there adoptions in your family tree that you would like to explore. (this is another heavy one for African-Americans. A lot of slaves could not read, write or speak English clearly who became free after the Civil War down south and north as well. Many migrated North and West looking for work and places for their families leaving their children with friends, neighbors or just disappearing under unusual circumstances. The people that kept theses children change their names or adopted them unofficially. Example: John Wilson and his family on the plantation may have changed to Amos Myatt and family. The DNA did not change. Understanding this and working through this is a challenge to any African-American researcher. This takes a real slow process of researching and genealogical detective work to find the connection.
  • Is your primary interest receiving a percentage breakdown of your ancestral origins or “Ethnicity”?

Currently there are tests geared at isolating types of DNA that can address these questions and others. They are the Y-chromosome DNA (Y-DNA), mitochondrial DNA (mtDNA) and the autosomal DNA (atDNA). Y-DNA has been in use the longest and has the best track record for helping genealogists demolish those proverbial brick walls.

Y-DNA refers to the DNA found on the Y chromosome. Only males inherit the Y chromosome, so this test can only be used to trace the direct paternal line. A father inherits his Y chromosome from his father who inherits it from his father who inherits it from his father and on and on. Ancient origins of a person’s direct paternal line.

Example from DNA test results my line. Johns’ family paternal line.

Unlike all other chromosomes, the Y chromosome does not undergo extensive recombination before it is passed down to the next generation. There can be some recombination between the two tips of the Y and X chromosomes, but those regions are not used for genetic genealogy.


The unique inheritance pattern of Y-DNA offers both advantages and limitations when applying test results to a genealogical problem. The lack of recombination means that the same Y-DNA footprint is passed down for many generations, allowing a line to be traced many generations back in time. The fact that the same Y-DNA footprint is passed down for many generations is a major advantage when trying to determine if a patrillineal line was a specific biogeographical origin, such as African or Native American. The origin-identifying markers will not be diluted by recombination and will persist through all generations.

Types of Y-DNA Testing

There are two main types of Y-DNA testing for genetic genealogy: Short Tandem Repeat (STRand Single Nucleotide Polymorphism (SNP).  

These test look at different kinds a markers, provide different information, and have different uses and limitations. I will take up more on this subject in the intermediate and advanced chapters at  later time.





Genetic Genealogy for Beginners – Introduction



Genetic Genealogy for beginners was created to describe Genetic Genealogy in a simpler manner. Rather than a scientific approach to explaining genetic genealogy and the method and processes used in DNA testing, a clear and understandable nonscientific educational tool is offered to you in several chapter modules. Right now millions of people worldwide have purchased DNA test kits to explore their family ancestors and people have used perhaps several testing companies with different results and matches. The goal is to clear the fog and provide the tools required to understand genetic genealogy DNA testing. (Going forward I will be using the term DNA interchangeably with genetic genealogy).

There is a real need to educate and to continuously educate and help genealogists (anyone researching their family ancestry), to grasp and understand the beneficial attributes and limitations of DNA testing and methodologies. In this introduction and other chapters to follow, you will develop the tools to understand genetic genealogy (DNA).

After studying the chapters, you will be able to apply DNA specific vernacular and genetic genealogy evidence to explain genealogical questions. I will  introduce types of DNA testing and how the test can be used for genealogy.

Genealogy (jene-ole-je) is a record or table of the descent of a person, family, or group from ancestor or ancestors; a family tree. It is the study or investigation of ancestry and family histories. (   Genetic Genealogy is the use of DNA testing in combination with traditional genealogical and historical records to infer relationships between individuals.  (https://en.wikipedia/wiki/international_Society_of_Genetic_Genealogy) Both type requires meeting the genealogical and genetic genealogical standards if conclusions and evidence can be considered creditable and can be followed by others to reach the same conclusion and or expand upon to work presented. This is how genetic genealogy as any other science evolves over time. It becomes better and better.

Over time this material will change and the chapter modules will be adjusted overtime as new research and methods are introduced.  I would recommend you subscribe to  in order to receive updates to your chapter module materials.

Genetic Genealogy for Beginners Contents

  • Introduction
  • Chapter 1: Basic Genetics
  • Chapter Module 2: Genetic Genealogy Standards
  • Chapter Module 3. Y-DNA Explained
  • Chapter Module 4. MtDNA Explained
  • Chapter Module 5. atDNA Explained
  • Chapter Module 6: BGA (Admixture) Explained


  • Appendix A     Glossary
  • Appendix B    Exercise’s (each chapter module includes and exercise to bring forward your learning experience)
  • Appendix C.    Suggestive Reading List (Offered also at

See chapter 1, next

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