Y DNA: Part 1 – Overview (2024)

This is Part 1 of a series about Y DNA and how to use it successfully for genealogy.

If you’re in need of a brief DNA testing overview, please read 4 Kinds of DNA for Genetic Genealogy.

Y DNA testing has so much to offer. In this overview article, I’m touching briefly on each of the major functions and features of Y DNA testing. Following articles in this series will focus on how to utilize each tool for genealogy and harvesting every snippet of information available.

If you have Y DNA results, you can sign on to your account at Family Tree DNA and follow along. Throughout these articles, we’ll step through every tab and function, how to use them, and what they mean to you.

What is Y DNA and Why Do I Care?

Y DNA is what makes males, well, male.

The 23^rd pair of human chromosomes consists of an X and a Y chromosome.

Female children inherit an X from both parents.

Male children inherit an X chromosome from their mother, but a Y from their father.

Generally, the Y chromosome follows the male surname line, so Estes males pass their Estes Y chromosome to their sons.

When adoptions occur, of course the surname of record does not match the biological surname associated with the Y chromosome – which is exactly why male adoptees take Y DNA tests.

Inheritance Path

In the example below, you can see that the light blue Y chromosome is passed from father to son to son to son to the male child in the current generation.

Click to enlarge

The dark blue maternal great-grandfather in this example also passes his Y chromosome to his son, but it stops there since the next generation in this tree is a female.

The light blue son at the bottom inherits a Y chromosome from his father, from ancestors all the way up that light blue line – along with his surname. The daughter doesn’t receive a Y chromosome nor do any females.

If you’re a male, you can test your own Y DNA of course.

If you’re a female, like the daughter, above, you must find a male in the line you seek to test. In this case, the brother, father, grandfather, paternal uncles and so forth represent her father’s Y DNA.

If you want information from any of the Y chromosome lineages in this chart that you don’t personally carry, you must find a male descended directly patrilineally from that line to test. It’s generally fairly easy to identify those people, because they will also carry the relevant surname. There are several examples in the article, Concepts – Who to Test for Your Father’s DNA.

Every Y DNA line has its own unique story for genealogists to harvest – assuming we can find an appropriate candidate for testing or find someone who has already tested. We’ll talk about how to see if your line may have already tested in the Projects section later in this article.

Why Y DNA Works

Y DNA is inherited from the patrilineal line directly. Unlike autosomal DNA, there is no genetic contribution from any females.

This uniquely male inheritance path allows us to use Y DNA for matching to other males beginning with the first generation, the father, then reaching back many generations providing a way to view our ancestral heritage beyond the line-in-the-sand boundary of surnames.

In other words, because Y DNA is not mixed with any DNA from the mothers, it’s very nearly identical to our patrilineal ancestors’ Y DNA – meaning it matches that of the father, and grandfather, reaching back many generations.

Some people, especially new autosomal testers, believe that Y DNA is ONLY useful for deep ancestry and not for genealogy. That’s ENTIRELY mistaken. Y DNA is extremely important in confirming descent from known ancestors. In fact, without Y DNA, you can’t tell the difference with autosomal testing between a child born to a male and a child born to the female of a couple. I wrote about that here.No one wants to spend years barking up the wrong tree.

Y DNA testing is also the single best way to push the Y DNA genealogy back further in time. It can and does identify the geographic source, overseas, of the DNA lineage, through matches to other testers as well as haplogroup matches. These are things autosomal DNA simply cannot accomplish.

In fact, Y DNA did exactly that for my own Speak(es) line, connecting us genetically to the Speak family from Downham, Lancashire, England which then facilitated discovering the actual baptism document of our immigrant ancestor. Finding our English geographic source had eluded researchers for decades. A year later, a group of 20+ descendants visited Downham and stood in that very church.

There simply is no better success story.

Migration Path Identified

Not only can Y DNA confirm recent ancestors and find ones more distant, by tracing a series of mutations, we can track our ancestor over time beginning with Y Line Adam, born in Africa tens of thousands of years ago to that church in an ancestral country and then to where we are today.

Mutations Happen

If mutations never occurred, the Y DNA of all males would be identical and therefore not useful for us to use for genealogy or to peer back in time beyond the advent of surnames.

Mutations do occur, just not on any schedule. This means that it’s difficult to predict how long ago we shared a common ancestor with someone else based solely on Y DNA mutations – although some types of mutations are better predictors than others.

A mutation might occur between a male and his father, or there might be no mutations for hundreds or even, potentially, thousands of years – depending on the marker type.

For example, in the Estes DNA project, one group of men have no STR (short tandem repeat) mutations in 8 generations. Others have several in the same number of generations.

Part of the success of matching genealogically with Y DNA testing has to do with:

The type of markers tested
The number of markers tested – testing fewer marker locations results in matches that are much less specific and therefore less relevant.
The luck of whether anyone else from your line has tested

The best results are between men who have taken the Big Y-700 test which provides for the largest number of STR markers and all SNPs (single nucleotide polymorphisms) , both previously known and discovered individually during that person’s Big Y test result.

Let’s take a look at the two different kinds of YDNA markers and their mutations.

Two Kinds of Mutations

Y DNA can be tested for two different kinds of mutations, STR (short tandem repeat) markers and SNPs (single nucleotide polymorphisms.)

All DNA is comprised of four different nucleotides, abbreviated by A, C, G and T.

A=adenine
C=cytosine
G=guanine
T=thymine

When mutations take place, they can take the form of three types of mutations:

A deletion occurs when a nucleotide, or multiple nucleotides, fail to copy during reproduction. Therefore, that location or locations are then blank, with no DNA at that location permanently.
A replacement occurs when a nucleotide is replaced or swapped out with a different nucleotide. For example, an A could be replaced with one of the other nucleotides, and so forth.
An insertion occurs when a nucleotide or a group of nucleotides is duplicated and inserted between existing nucleotides.

Let’s look at how this actually works.

Here’s an example segment of DNA.

A deletion would occur if the leading A (or a series of nucleotides) were simply gone.

A replacement would occur if the first A above were to change to T or G or C as in the example below:

A replacement is a SNP mutation.

An insertion would be where DNA is inserted between existing nucleotide locations.

Note the extra red CTs that have been inserted. Specifically, 4 extra CTs, for a total of 5 sets of CT. This is the definition of a STR, a short tandem repeat mutation.

STR markers, known as short tandem repeats, accrue what are similar to copy machine errors. This occurs when a specific segment of Y DNA gets repeated several times in a row. In other words, the copy machine gets stuck.

STR Markers

We purchase STR Y DNA tests from Family Tree DNA grouped into panels that include a specific number of markers.

Example of 37 marker results – click to enlarge

These panels consist of the following number of marker locations:

12 markers (now obsolete)
25 markers (now obsolete)
37 markers
67 markers (replaced by 111)
111 markers
500 markers bundled as part of the now-obsolete Big Y-500
700 markers bundled with the Big Y-700

The more markers purchased, the more data points to be compared, and the more relevant and convincing the results.

What Matches See

The STR matches and SNP matches look different on the tester’s results page.

Click to enlarge

People whom you match on STR panels can see that you do match, if you’ve opted-in to matching, but they can’t see specific differences or mutations. They see the name you’ve entered for yourself, your earliest known ancestor and your match can send e-mail to you. Aside from that, they can’t see your results or mutations unless you’ve joined a public project.

Click to enlarge

Within projects, participant names cannot be listed publicly. In other words, your matches can’t tell that it’s you unless you tell them your kit number or they recognize your earliest known ancestor on the project page and you are the only person with that ancestor.

The Big Y-700 test tests all STR markers in addition to scanning the entire Y chromosome for all SNP (haplogroup defining) mutations. They have the STR matches page like everyone else, but they also have an additional Big Ypage.

People who have taken the Big Y test see a different view of matches on their Big Y matches tab. This is true for either the original Big Y, Big Y-500 which includes a minimum of 500 STR markers or the current Big Y-700 test which includes a minimum of 700 STR markers. (You can always upgrade to the Big Y-700 from earlier tests.)

For SNP markers only, above, Big Y matches can see who they match and the SNPs they do and don’t match with that person in common.

For STR markers available only under the Big Y umbrella, meaning above 111 markers, results are displayed under the Y DNA Matches tab in the Big Y STR Differences column, below.

Click to enlarge

You can easily see that only one man on this match list has also taken the Big Y test, and he had 2 differences out of 440 markers. That’s in addition to 2 differences in the first 111 markers, for a total of 4 differences (mutations) in 551 markers.

Researching Without Testing

The great news is that even if you’ve just ordered your test and are waiting for results, you can research and join projects now.

For that matter, you can research using public projects without testing by going to the main Family Tree DNA webpage, scroll down and simply entering the surname of interest into the search box.

You’ll be directed to surname projects where you can view ancestors and results of anonymized project members.

Give it a try to see what comes up for your surnames of interest.

Project Results

Projects atFamily Tree DNA provide testers with access to volunteer administrators who help users with various types of information. Administrators also cluster users in projects that are meaningful to their research.

Most Y DNA testers immediately join their surname project.

Using the Estes surname project as an example, you can see that I’ve grouped the project members in ways I feel will be helpful to their genealogy.

The Paternal Ancestor Names are particularly helpful to testers as well as people who are interested in testing in order to determine whether or not they are descended from a specific line.

It’s very useful to be able to discern if someone from your line has already tested – because it provides someone for you to match against, or not, as the case may be.

The haplogroup C-P39 Y DNA project is shown above with the Paternal Ancestor Name as provided by testers that reflects Native American and First Nations ancestors.

Another important project feature is the project map function, allowing testers in a specific haplogroup (C-P39 below) to view the locations of the earliest known ancestors of other members of the same haplogroup – whether project members match each other or not. Your Native ancestors traveled with theirs and descended from a common ancestor. Cool, huh!

What’s the story associated with the pin distribution of the C-P39 project, above? I wish we knew, and we may someday as research progresses. Whatever it is, it’s probably important genealogically.

Another type of project to join is a geographical or interest group project.

The Acadian AmerIndian Project welcomes descendants who have tested the Y, autosomal and/or mitochondrial DNA of the various Acadian families which includes French and English settlers along with First Nations indigenous ancestors.

The map below shows the distribution of Y DNA members of the Acadian Amerindian project diaspora before and after Le Grand Dérangement” that scattered their descendants to the winds.

The pins on the Acadian Amerindian project map above are color coded by haplogroup.

Projects such as this facilitate genealogists discovering the haplogroup and related information about their direct line ancestor without personally testing.

For example, if Germain Doucet born about 1641, part of the mustard-colored group above, is my ancestor, by viewing and/or joining this project, I can obtain this information about my ancestor. Project members can see more than casual browsers, because some testers only choose to display results to other project members and some projects are private, with results only displayed to project members. Many surname projects accept descendants who don’t carry the surname itself.

I obviously can’t personally test for Germain Doucet’s Y DNA myself, but thankfully, others who do descend patrilineally from Germain Doucet have been generous enough to test and share by joining this project.

Furthermore, I can contact the tester through the project administrator(s) and gain a great cousin with potentially LOTS of information.

Just think how useful Y DNA would be to genealogists if everyone tested!

Finding Projects to Join

I encourage all testers to join appropriate haplogroup projects. Often, more than one haplogroup project exists for each Y DNA letter, such as C or R. Generally, there are many subgroups for each core haplogroup and you may want to join more than one depending on your results.

I encourage testers to browse the selections and join other interest projects. For example, there are projects such as the Anabaptist Project which focuses on an endogamous religious sect, French-Swiss which is regional, or the American Indian project for people researching Native ancestry, in addition to relevant surname and haplogroup project(s). There are more than 10,000 total (well-organized) projects to choose from.

Your project selections may be a huge benefit to someone else as well as to your own research. Y DNA testing and matching is your best bet for jumping the pond and finding connections overseas.

How to Join Projects

Sign onto your personal page atFamily Tree DNAand click on myProjects at the top, then on “Join A Project.”

Next, you’ll see a list of projects in which your surname appears. These may or may not be relevant for you.

Click to enlarge

You can search by surname.

More importantly, you can browse in any number of sections.

For Y DNA, I would suggest specifically surnames, of course, Y DNA haplogroups along with Y DNA Geographical Projects, and Dual Geographical Projects.

Click to enlarge

When you find a project of interest, click to read the description written by the volunteer administrators to see if it’s a good fit for you, then click through to join.

Next Article in the Series

Of course, you’re probably wondering what all of those numbers in your results and shown in projects mean. The next article in a couple weeks will address the meaning of STR marker results.

Testing

If you haven’t yet Y DNA tested and you want to know what secrets your Y DNA holds, you can order your Y DNA test here.

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