Concepts: Inheritance

Inheritance.

What is it?

How does it work?

I’m not talking about possessions – but about the DNA that you receive from your parents, and their parents.

The reason that genetic genealogy works is because of inheritance. You inherit DNA from your parents in a known and predictable fashion.

Fortunately, we have more than one kind of DNA to use for genealogy.

Types of DNA

Females have 3 types of DNA and males have 4. These different types of DNA are inherited in various ways and serve different genealogical purposes.

Males Females
Y DNA Yes No
Mitochondrial DNA Yes Yes
Autosomal DNA Yes Yes
X Chromosome Yes, their mother’s only Yes, from both parents

Different Inheritance Paths

Different types of DNA are inherited from different ancestors, down different ancestral paths.

Inheritance Paths

The inheritance path for Y DNA is father to son and is inherited by the brother, in this example, from his direct male ancestors shown by the blue arrow. The sister does not have a Y chromosome.

The inheritance path for the red mitochondrial DNA for both the brother and sister is from the direct matrilineal ancestors, only, shown by the red arrow.

Autosomal DNA is inherited from all ancestral lines on both the father’s and mother’s side of your tree, as illustrated by the broken green arrow.

The X chromosome has a slightly different inheritance path, depending on whether you are a male or female.

Let’s take a look at each type of inheritance, how it works, along with when and where it’s useful for genealogy.

Autosomal DNA

Autosomal DNA testing is the most common. It’s the DNA that you inherit from both of your parents through all ancestral lines back in time several generations. Autosomal DNA results in matches at the major testing companies such as FamilyTreeDNA, MyHeritage, Ancestry, and 23andMe where testers view trees or other hints, hoping to determine a common ancestor.

How does autosomal DNA work?

22 autosomes

Every person has two each of 22 chromosomes, shown above, meaning one copy is contributed by your mother and one copy by your father. Paired together, they form the two-sided shape we are familiar with.

For each pair of chromosomes, you receive one from your father, shown with a blue arrow under chromosome 1, and one from your mother, shown in red. In you, these are randomly combined, so you can’t readily tell which piece comes from which parent. Therein lies the challenge for genealogy.

This inheritance pattern is the same for all chromosomes, except for the 23rd pair of chromosomes, at bottom right, which determined the sex of the child.

The 23rd chromosome pair is inherited differently for males and females. One copy is the Y chromosome, shown in blue, and one copy is the X, shown in red. If you receive a Y chromosome from your father, you’re a male. If you receive an X from your father, you’re a female.

Autosomal Inheritance

First, let’s talk about how chromosomes 1-22 are inherited, omitting chromosome 23, beginning with grandparents.

Inheritance son daughter

Every person inherits precisely half of each of their parents’ autosomal DNA. For example, you will receive one copy of your mother’s chromosome 1. Your mother’s chromosome 1 is a combination of her mother’s and father’s chromosome 1. Therefore, you’ll receive ABOUT 25% of each of your grandparents’ chromosome 1.

Inheritance son daughter difference

In reality, you will probably receive a different amount of your grandparent’s DNA, not exactly 25%, because your mother or father will probably contribute slightly more (or less) of the DNA of one of their parents than the other to their offspring.

Which pieces of DNA you inherit from your parents is random, and we don’t know how the human body selects which portions are and are not inherited, other than we know that large pieces are inherited together.

Therefore, the son and daughter won’t inherit the exact same segments of the grandparents’ DNA. They will likely share some of the same segments, but not all the same segments.

Inheritance maternal autosomalYou’ll notice that each parent carries more of each color DNA than they pass on to their own children, so different children receive different pieces of their parents’ DNA, and varying percentages of their grandparents’ DNA.

I wrote about a 4 Generation Inheritance Study, here.

Perspective

Keep in mind that you will only inherit half of the DNA that each of your parents carries.

Looking at a chromosome browser, you match your parents on all of YOUR chromosomes.

Inheritance parental autosomal

For example, this is me compared to my father. I match my father on either his mother’s side, or his father’s side, on every single location on MY chromosomes. But I don’t match ALL of my father’s DNA, because I only received half of what he has.

From your parents’ perspective, you only have half of their DNA.

Let’s look at an illustration.

Inheritance mom dad

Here is an example of one of your father’s pairs of chromosomes 1-22. It doesn’t matter which chromosome, the concepts are the same.

He inherited the blue chromosome from his father and the pink chromosome from his mother.

Your father contributed half of his DNA to you, but that half is comprised of part of his father’s chromosome, and part of his mother’s chromosome, randomly selected in chunks referred to as segments.

Inheritance mom dad segments

Your father’s chromosomes are shown in the upper portion of the graphic, and your chromosome that you inherited from you father is shown below.

On your copy of your father’s chromosome, I’ve darkened the dark blue and dark pink segments that you inherited from him. You did not receive the light blue and light pink segments. Those segments of DNA are lost to your line, but one of your siblings might have inherited some of those pieces.

Inheritance mom dad both segments

Now, I’ve added the DNA that you inherited from your Mom into the mixture. You can see that you inherited the dark green from your Mom’s father and the dark peach from your Mom’s mother.

Inheritance grandparents dna

These colored segments reflect the DNA that you inherited from your 4 grandparents on this chromosome.

I often see questions from people wondering how they match someone from their mother’s side and someone else from their father’s side – on the same segment.

Understanding that you have a copy of the same chromosome from your mother and one from your father clearly shows how this happens.

Inheritance match 1 2

You carry a chromosome from each parent, so you will match different people on the same segment. One match is to the chromosome copy from Mom, and one match is to Dad’s DNA.

Inheritance 4 gen

Here is the full 4 generation inheritance showing Match 1 matching a segment from your Dad’s father and Match 2 matching a segment from your Mom’s father.

Your Parents Will Have More Matches Than You Do

From your parents’ perspective, you will only match (roughly) half of the DNA with other people that they will match. On your Dad’s side, on segment 1, you won’t match anyone pink because you didn’t inherit your paternal grandmother’s copy of segment 1, nor did you inherit your maternal grandmother’s segment 1 either. However, your parents will each have matches on those segments of DNA that you didn’t inherit from them.

From your perspective, one or the other of your parents will match ALL of the people you match – just like we see in Match 1 and Match 2.

Matching you plus either of your parents, on the same segment, is exactly how we determine whether a match is valid, meaning identical by descent, or invalid, meaning identical by chance. I wrote about that in the article, Concepts: Identical by…Descent, State, Population and Chance.

Inheritance on chromosomes 1-22 works in this fashion. So does the X chromosome, fundamentally, but the X chromosome has a unique inheritance pattern.

X Chromosome

The X chromosome is inherited differently for males as compared to females. This is because the 23rd pair of chromosomes determines a child’s sex.

If the child is a female, the child inherits an X from both parents. Inheritance works the same way as chromosomes 1-22, conceptually, but the inheritance path on her father’s side is different.

If the child is a male, the father contributes a Y chromosome, but no X, so the only X chromosome a male has is his mother’s X chromosome.

Males inherit X chromosomes differently than females, so a valid X match can only descend from certain ancestors on your tree.

inheritance x fan

This is my fan chart showing the X chromosome inheritance path, generated by using Charting Companion. My father’s paternal side of his chart is entirely blank – because he only received his X chromosome from his mother.

You’ll notice that the X chromosome can only descend from any male though his mother – the effect being a sort of checkerboard inheritance pattern. Only the pink and blue people potentially contributed all or portions of X chromosomes to me.

This can actually be very useful for genealogy, because several potential ancestors are immediately eliminated. I cannot have any X chromosome segment from the white boxes with no color.

The X Chromsome in Action

Here’s an X example of how inheritance works.

Inheritance X

The son inherits his entire X chromosome from his mother. She may give him all of her father’s or mother’s X, or parts of both. It’s not uncommon to find an entire X chromosome inherited. The son inherits no X from his father, because he inherits the Y chromosome instead.

Inheritance X daughter

The daughter inherits her father’s X chromosome, which is the identical X chromosome that her father inherited from his mother. The father doesn’t have any other X to contribute to his daughter, so like her father, she inherits no portion of an X chromosome from her paternal grandfather.

The daughter also received segments of her mother’s X that her mother inherited maternally and paternally. As with the son, the daughter can receive an entire X chromosome from either her maternal grandmother or maternal grandfather.

This next illustration ONLY pertains to chromosome 23, the X and Y chromosomes.

Inheritance x y

You can see in this combined graphic that the Y is only inherited by sons from one direct line, and the father’s X is only inherited by his daughter.

X chromosome results are included with autosomal results at both Family Tree DNA and 23andMe, but are not provided at MyHeritage. Ancestry, unfortunately, does not provide segment information of any kind, for the X or chromosomes 1-22. You can, however, transfer the DNA files to Family Tree DNA where you can view your X matches.

Note that X matches need to be larger than regular autosomal matches to be equally as useful due to lower SNP density. I use 10-15 cM as a minimum threshold for consideration, equivalent to about 7 cM for autosomal matches. In other words, roughly double the rule of thumb for segment size matching validity.

Autosomal Education

My blog is full of autosomal educational articles and is fully keyword searchable, but here are two introductory articles that include information from the four major vendors:

When to Purchase Autosomal DNA Tests

Literally, anytime you want to work on genealogy to connect with cousins, prove ancestors or break through brick walls.

  • Purchase tests for yourself and your siblings if both parents aren’t living
  • Purchase tests for both parents
  • Purchase tests for all grandparents
  • Purchase tests for siblings of your parents or your grandparents – they have DNA your parents (and you) didn’t inherit
  • Test all older generation family members
  • If the family member is deceased, test their offspring
  • Purchase tests for estimates of your ethnicity or ancestral origins

Y DNA

Y DNA is only inherited by males from males. The Y chromosome is what makes a male, male. Men inherit the Y chromosome intact from their father, with no contribution from the mother or any female, which is why men’s Y DNA matches that of their father and is not diluted in each generation.

Inheritance y mtdna

If there are no adoptions in the line, known or otherwise, the Y DNA will match men from the same Y DNA line with only small differences for many generations. Eventually, small changes known as mutations accrue. After many accumulated mutations taking several hundred years, men no longer match on special markers called Short Tandem Repeats (STR). STR markers generally match within the past 500-800 years, but further back in time, they accrue too many mutations to be considered a genealogical-era match.

Family Tree DNA sells this test in 67 and 111 marker panels, along with a product called the Big Y-700.

The Big Y-700 is the best-of-class of Y DNA tests and includes at least 700 STR markers along with SNPs which are also useful genealogically plus reach further back in time to create a more complete picture.

The Big Y-700 test scans the entire useful portion of the Y chromosome, about 15 million base pairs, as compared to 67 or 111 STR locations.

67 and 111 Marker Panel Customers Receive:

  • STR marker matches
  • Haplogroup estimate
  • Ancestral Origins
  • Matches Map showing locations of the earliest known ancestors of matches
  • Haplogroup Origins
  • Migration Maps
  • STR marker results
  • Haplotree and SNPs
  • SNP map

Y, mitochondrial and autosomal DNA customers all receive options for Advanced Matching.

Big Y-700 customers receive, in addition to the above:

  • All of the SNP markers in the known phylotree shown publicly, here
  • A refined, definitive haplogroup
  • Their place on the Block Tree, along with their matches
  • New or unknown private SNPs that might lead to a new haplogroup, or genetic clan, assignment
  • 700+ STR markers
  • Matching on both the STR markers and SNP markers, separately

Y DNA Education

I wrote several articles about understanding and using Y DNA:

When to Purchase Y DNA Tests

The Y DNA test is for males who wish to learn more about their paternal line and match against other men to determine or verify their genealogical lineage.

Women cannot test directly, but they can purchase the Y DNA test for men such as fathers, brothers, and uncles.

If you are purchasing for someone else, I recommend purchasing the Big Y-700 initially.

Why purchase the Big Y-700, when you can purchase a lower level test for less money? Because if you ever want to upgrade, and you likely will, you have to contact the tester and obtain their permission to upgrade their test. They may be ill, disinterested, or deceased, and you may not be able to upgrade their test at that time, so strike while the iron is hot.

The Big Y-700 provides testers, by far, the most Y DNA data to work (and fish) with.

Mitochondrial DNA

Inheritance mito

Mitochondrial DNA is passed from mothers to both sexes of their children, but only females pass it on.

In your tree, you and your siblings all inherit your mother’s mitochondrial DNA. She inherited it from her mother, and your grandmother from her mother, and so forth.

Mitochondrial DNA testers at FamilyTreeDNA receive:

  • A definitive haplogroup, thought of as a genetic clan
  • Matching
  • Matches Map showing locations of the earliest know ancestors of matches
  • Personalized mtDNA Journey video
  • Mutations
  • Haplogroup origins
  • Ancestral origins
  • Migration maps
  • Advanced matching

Of course, Y, mitochondrial and autosomal DNA testers can join various projects.

Mitochondrial DNA Education

I created a Mitochondrial DNA page with a comprehensive list of educational articles and resources.

When to Purchase Mitochondrial DNA Tests

Mitochondrial DNA can be valuable in terms of matching as well as breaking down brick walls for women ancestors with no surnames. You can also use targeted testing to prove, or disprove, relationship theories.

Furthermore, your mitochondrial DNA haplogroup, like Y DNA haplogroups, provides information about where your ancestors came from by identifying the part of the world where they have the most matches.

You’ll want to purchase the mtFull sequence test provided by Family Tree DNA. Earlier tests, such as the mtPlus, can be upgraded. The full sequence test tests all 16,569 locations on the mitochondria and provides testers with the highest level matching as well as their most refined haplogroup.

The full sequence test is only sold by Family Tree DNA and provides matching along with various tools. You’ll also be contributing to science by building the mitochondrial haplotree of womankind through the Million Mito Project.

Combined Resources for Genealogists

You may need to reach out to family members to obtain Y and mitochondrial DNA for your various genealogical lines.

For example, the daughter in the tree below, a genealogist, can personally take an autosomal test along with a mitochondrial test for her matrilineal line, but she cannot test for Y DNA, nor can she obtain her paternal grandmother’s mitochondrial DNA directly by testing herself.

Hearts represent mitochondrial DNA, and stars, Y DNA.

Inheritance combined

However, our genealogist’s brother, father or grandfather can test for her father’s (blue star) Y DNA.

Her father or any of his siblings can test for her paternal grandmother’s (hot pink heart) mitochondrial DNA, which provides information not available from any other tester in this tree, except for the paternal grandmother herself.

Our genealogist’s paternal grandfather, and his siblings, can test for his mother’s (yellow heart) mitochondrial DNA.

Our genealogist’s maternal grandfather can test for his (green star) Y DNA and (red heart) mitochondrial DNA.

And of course, it goes without saying that every single generation upstream of the daughter, our genealogist, should all take autosomal DNA tests.

So, with several candidates, who can and should test for what?

Person Y DNA Mitochondrial Autosomal
Daughter No Y – can’t test Yes, her pink mother’s Yes – Test
Son Yes – blue Y Yes, his pink mother’s Yes – Test
Father Yes – blue Y Yes – his magenta mother’s Yes – Test
Paternal Grandfather Yes – blue Y – Best to Test Yes, his yellow mother’s – Test Yes – Test
Mother No Y – can’t test Yes, her pink mother’s Yes – Test
Maternal Grandmother No Y – can’t test Yes, her pink mother’s – Best to Test Yes – Test
Maternal Grandfather Yes – green Y – Test Yes, his red mother’s – Test Yes – Test

The best person/people to test for each of the various lines and types of DNA is shown bolded above…assuming that all people are living. Of course, if they aren’t, then test anyone else in the tree who carries that particular DNA – and don’t forget to consider aunts and uncles, or their children, as candidates.

If one person takes the Y and/or mitochondrial DNA test to represent a specific line, you don’t need another person to take the same test for that line. The only possible exception would be to confirm a specific Y DNA result matches a lineage as expected.

Looking at our three-generation example, you’ll be able to obtain a total of two Y DNA lines, three mitochondrial DNA lines, and 8 autosomal results, helping you to understand and piece together your family line.

You might ask, given that the parents and grandparents have all autosomally tested in this example, if our genealogist really needs to test her brother, and the answer is probably not – at least not today.

However, in cases like this, I do test the sibling, simply because I can learn and it may encourage their interest or preserve their DNA for their children who might someday be interested. We also don’t know what kind of advances the future holds.

If the parents aren’t both available, then you’ll want to test as many of your (and their) siblings as possible to attempt to recover as much of the parents’ DNA, (and matches) as possible.

Your family members’ DNA is just as valuable to your research as your own.

Increase Your Odds

Don’t let any of your inherited DNA go unused.

You can increase your odds of having autosomal matches by making sure you are in all 4 major vendor databases.

Both FamilyTreeDNA and MyHeritage accept transfers from 23andMe and Ancestry, who don’t accept transfers. Transferring and matching is free, and their unlock fees, $19 at FamilyTreeDNA, and $29 at MyHeritage, respectively, to unlock their advanced tools are both less expensive than retesting.

You’ll find easy-to-follow step-by-step transfer instructions to and from the vendors in the article DNA File Upload-Download and Transfer Instructions to and from DNA Testing Companies.

Order

You can order any of the tests mentioned above by clicking on these links:

Autosomal:

Transfers

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Disclosure

I receive a small contribution when you click on some of the links to vendors in my articles. This does NOT increase the price you pay but helps me to keep the lights on and this informational blog free for everyone. Please click on the links in the articles or to the vendors below if you are purchasing products or DNA testing.

Thank you so much.

DNA Purchases and Free Transfers

Genealogy Products and Services

Genealogy Research

Y DNA: Step-by-Step Big Y Analysis

Many males take the Big Y-700 test offered by FamilyTreeDNA, so named because testers receive the most granular haplogroup SNP results in addition to 700+ included STR marker results. If you’re not familiar with those terms, you might enjoy the article, STRs vs SNPs, Multiple DNA Personalities.

The Big Y test gives testers the best of both, along with contributing to the building of the Y phylotree. You can read about the additions to the Y tree via the Big Y, plus how it helped my own Estes project, here.

Some men order this test of their own volition, some at the request of a family member, and some in response to project administrators who are studying a specific topic – like a particular surname.

The Big Y-700 test is the most complete Y DNA test offered, testing millions of locations on the Y chromosome to reveal mutations, some unique and never before discovered, many of which are useful to genealogists. The Big Y-700 includes the traditional Y DNA STR marker testing along with SNP results that define haplogroups. Translated, both types of test results are compared to other men for genealogy, which is the primary goal of DNA testing.

Being a female, I often recruit males in my family surname lines and sponsor testing. My McNiel line, historic haplogroup R-M222, has been particularly frustrating both genealogically as well as genetically after hitting a brick wall in the 1700s. My McNeill cousin agreed to take a Big Y test, and this analysis walks through the process of understanding what those results are revealing.

After my McNeill cousin’s Big Y results came back from the lab, I spent a significant amount of time turning over every leaf to extract as much information as possible, both from the Big Y-700 DNA test itself and as part of a broader set of intertwined genetic information and genealogical evidence.

I invite you along on this journey as I explain the questions we hoped to answer and then evaluate Big Y DNA results along with other information to shed light on those quandaries.

I will warn you, this article is long because it’s a step-by-step instruction manual for you to follow when interpreting your own Big Y results. I’d suggest you simply read this article the first time to get a feel for the landscape, before working through the process with your own results. There’s so much available that most people leave laying on the table because they don’t understand how to extract the full potential of these test results.

If you’d like to read more about the Big Y-700 test, the FamilyTreeDNA white paper is here, and I wrote about the Big Y-700 when it was introduced, here.

You can read an overview of Y DNA, here, and Y DNA: The Dictionary of DNA, here.

Ok, get yourself a cuppa joe, settle in, and let’s go!

George and Thomas McNiel – Who Were They?

George and Thomas McNiel appear together in Spotsylvania County, Virginia records. Y DNA results, in combination with early records, suggest that these two men were brothers.

I wrote about discovering that Thomas McNeil’s descendant had taken a Y DNA test and matched George’s descendants, here, and about my ancestor George McNiel, here.

McNiel family history in Wilkes County, NC, recorded in a letter written in 1898 by George McNiel’s grandson tells us that George McNiel, born about 1720, came from Scotland with his two brothers, John and Thomas. Elsewhere, it was reported that the McNiel brothers sailed from Glasgow, Scotland and that George had been educated at the University of Edinburgh for the Presbyterian ministry but had a change of religious conviction during the voyage. As a result, a theological tiff developed that split the brothers.

George, eventually, if not immediately, became a Baptist preacher. His origins remain uncertain.

The brothers reportedly arrived about 1750 in Maryland, although I have no confirmation. By 1754, Thomas McNeil appeared in the Spotsylvania County, VA records with a male being apprenticed to him as a tailor. In 1757, in Spotsylvania County, the first record of George McNeil showed James Pey being apprenticed to learn the occupation of tailor.

If George and Thomas were indeed tailors, that’s not generally a country occupation and would imply that they both apprenticed as such when they were growing up, wherever that was.

Thomas McNeil is recorded in one Spotsylvania deed as being from King and Queen County, VA. If this is the case, and George and Thomas McNiel lived in King and Queen, at least for a time, this would explain the lack of early records, as King and Queen is a thrice-burned county. If there was a third brother, John, I find no record of him.

My now-deceased cousin, George McNiel, initially tested for the McNiel Y DNA and also functioned for decades as the family historian. George, along with his wife, inventoried the many cemeteries of Wilkes County, NC.

George believed through oral history that the family descended from the McNiel’s of Barra.

McNiel Big Y Kisumul

George had this lovely framed print of Kisimul Castle, seat of the McNiel Clan on the Isle of Barra, proudly displayed on his wall.

That myth was dispelled with the initial DNA testing when our line did not match the Barra line, as can be seen in the MacNeil DNA project, much to George’s disappointment. As George himself said, the McNiel history is both mysterious and contradictory. Amen to that, George!

McNiel Big Y Niall 9 Hostages

However, in place of that history, we were instead awarded the Niall of the 9 Hostages badge, created many years ago based on a 12 marker STR result profile. Additionally, the McNiel DNA was assigned to haplogroup R-M222. Of course, today’s that’s a far upstream haplogroup, but 15+ years ago, we had only a fraction of the testing or knowledge that we do today.

The name McNeil, McNiel, or however you spell it, resembles Niall, so on the surface, this made at least some sense. George was encouraged by the new information, even though he still grieved the loss of Kisimul Castle.

Of course, this also caused us to wonder about the story stating our line had originated in Scotland because Niall of the 9 Hostages lived in Ireland.

Niall of the 9 Hostages

Niall of the 9 Hostages was reportedly a High King of Ireland sometime between the 6th and 10th centuries. However, actual historical records place him living someplace in the mid-late 300s to early 400s, with his death reported in different sources as occurring before 382 and alternatively about 411. The Annals of the Four Masters dates his reign to 379-405, and Foras Feasa ar Eirinn says from 368-395. Activities of his sons are reported between 379 and 405.

In other words, Niall lived in Ireland about 1500-1600 years ago, give or take.

Migration

Generally, migration was primarily from Scotland to Ireland, not the reverse, at least as far as we know in recorded history. Many Scottish families settled in the Ulster Plantation beginning in 1606 in what is now Northern Ireland. The Scots-Irish immigration to the states had begun by 1718. Many Protestant Scottish families immigrated from Ireland carrying the traditional “Mc” names and Presbyterian religion, clearly indicating their Scottish heritage. The Irish were traditionally Catholic. George could have been one of these immigrants.

We have unresolved conflicts between the following pieces of McNeil history:

  • Descended from McNeil’s of Barra – disproved through original Y DNA testing.
  • Immigrated from Glasgow, Scotland, and schooled in the Presbyterian religion in Edinburgh.
  • Descended from the Ui Neill dynasty, an Irish royal family dominating the northern half of Ireland from the 6th to 10th centuries.

Of course, it’s possible that our McNiel/McNeil line could have been descended from the Ui Neill dynasty AND also lived in Scotland before immigrating.

It’s also possible that they immigrated from Ireland, not Scotland.

And finally, it’s possible that the McNeil surname and M222 descent are not related and those two things are independent and happenstance.

A New Y DNA Tester

Since cousin George is, sadly, deceased, we needed a new male Y DNA tester to represent our McNiel line. Fortunately, one such cousin graciously agreed to take the Big Y-700 test so that we might, hopefully, answer numerous questions:

  • Does the McNiel line have a unique haplogroup, and if so, what does it tell us?
  • Does our McNiel line descend from Ireland or Scotland?
  • Where are our closest geographic clusters?
  • What can we tell by tracing our haplogroup back in time?
  • Do any other men match the McNiel haplogroup, and what do we know about their history?
  • Does the Y DNA align with any specific clans, clan history, or prehistory contributing to clans?

With DNA, you don’t know what you don’t know until you test.

Welcome – New Haplogroup

I was excited to see my McNeill cousin’s results arrive. He had graciously allowed me access, so I eagerly took a look.

He had been assigned to haplogroup R-BY18350.

McNiel Big Y branch

Initially, I saw that indeed, six men matched my McNeill cousin, assigned to the same haplogroup. Those surnames were:

  • Scott
  • McCollum
  • Glass
  • McMichael
  • Murphy
  • Campbell

Notice that I said, “were.” That’s right, because shortly after the results were returned, based on markers called private variants, Family Tree DNA assigned a new haplogroup to my McNeill cousin.

Drum roll please!!!

Haplogroup R-BY18332

McNiel Big Y BY18332

Additionally, my cousin’s Big Y test resulted in several branches being split, shown on the Block Tree below.

McNIel Big Y block tree

How cool is this!

This Block Tree graphic shows, visually, that our McNiel line is closest to McCollum and Campbell testers, and is a brother clade to those branches showing to the left and right of our new R-BY18332. It’s worth noting that BY25938 is an equivalent SNP to BY18332, at least today. In the future, perhaps another tester will test, allowing those two branches to be further subdivided.

Furthermore, after the new branches were added, Cousin McNeill has no more Private Variants, which are unnamed SNPs. There were all utilized in naming additional tree branches!

I wrote about the Big Y Block Tree here.

Niall (Or Whoever) Was Prolific

The first thing that became immediately obvious was how successful our progenitor was.

McNiel Big Y M222 project

click to enlarge

In the MacNeil DNA project, 38 men with various surname spellings descend from M222. There are more in the database who haven’t joined the MacNeil project.

Whoever originally carried SNP R-M222, someplace between 2400 and 5900 years ago, according to the block tree, either had many sons who had sons, or his descendants did. One thing is for sure, his line certainly is in no jeopardy of dying out today.

The Haplogroup R-M222 DNA Project, which studies this particular haplogroup, reads like a who’s who of Irish surnames.

Big Y Match Results

Big Y matches must have no more than 30 SNP differences total, including private variants and named SNPs combined. Named SNPs function as haplogroup names. In other words, Cousin McNeill’s terminal SNP, meaning the SNP furthest down on the tree, R-BY18332, is also his haplogroup name.

Private variants are mutations that have occurred in the line being tested, but not yet in other lines. Occurrences of private variants in multiple testers allow the Private Variant to be named and placed on the haplotree.

Of course, Family Tree DNA offers two types of Y DNA testing, STR testing which is the traditional 12, 25, 37, 67 and 111 marker testing panels, and the Big Y-700 test which provides testers with:

  • All 111 STR markers used for matching and comparison
  • Another 589+ STR markers only available through the Big Y test increasing the total STR markers tested from 111 to minimally 700
  • A scan of the Y chromosome, looking for new and known SNPs and STR mutations

Of course, these tests keep on giving, both with matching and in the case of the Big Y – continued haplogroup discovery and refinement in the future as more testers test. The Big Y is an investment as a test that keeps on giving, not just a one-time purchase.

I wrote about the Big Y-700 when it was introduced here and a bit later here.

Let’s see what the results tell us. We’ll start by taking a look at the matches, the first place that most testers begin.

Mcniel Big Y STR menu

Regular Y DNA STR matching shows the results for the STR results through 111 markers. The Big Y section, below, provides results for the Big Y SNPs, Big Y matches and additional STR results above 111 markers.

McNiel Big Y menu

Let’s take a look.

STR and SNP Testing

Of Cousin McNeil’s matches, 2 Big Y testers and several STR testers carry some variant of the Neal, Neel, McNiel, McNeil, O’Neil, etc. surnames by many spellings.

While STR matching is focused primarily on a genealogical timeframe, meaning current to roughly 500-800 years in the past, SNP testing reaches much further back in time.

  • STR matching reaches approximately 500-800 years.
  • Big Y matching reaches approximately 1500 years.
  • SNPs and haplogroups reach back infinitely, and can be tracked historically beyond the genealogical timeframe, shedding light on our ancestors’ migration paths, helping to answer the age-old question of “where did we come from.”

These STR and Big Y time estimates are based on a maximum number of mutations for testers to be considered matches paired with known genealogy.

Big Y results consider two men a match if they have 30 or fewer total SNP differences. Using NGS (next generation sequencing) scan technology, the targeted regions of the Y chromosome are scanned multiple times, although not all regions are equally useful.

Individually tested SNPs are still occasionally available in some cases, but individual SNP testing has generally been eclipsed by the greatly more efficient enriched technology utilized with Big Y testing.

Think of SNP testing as walking up to a specific location and taking a look, while NGS scan technology is a drone flying over the entire region 30-50 times looking multiple times to be sure they see the more distant target accurately.

Multiple scans acquiring the same read in the same location, shown below in the Big Y browser tool by the pink mutations at the red arrow, confirm that NGS sequencing is quite reliable.

McNiel Big Y browser

These two types of tests, STR panels 12-111 and the SNP-based Big Y, are meant to be utilized in combination with each other.

STR markers tend to mutate faster and are less reliable, experiencing frustrating back mutations. SNPs very rarely experience this level of instability. Some regions of the Y chromosome are messier or more complicated than others, causing problems with interpreting reads reliably.

For purposes of clarity, the string of pink A reads above is “not messy,” and “A” is very clearly a mutation because all ~39 scanned reads report the same value of “A,” and according to the legend, all of those scans are high quality. Multiple combined reads of A and G, for example, in the same location, would be tough to call accurately and would be considered unreliable.

You can see examples of a few scattered pink misreads, above.

The two different kinds of tests produce results for overlapping timeframes – with STR mutations generally sifting through closer relationships and SNPs reaching back further in time.

Many more men have taken the Y DNA STR tests over the last 20 years. The Big Y tests have only been available for the past handful of years.

STR testing produces the following matches for my McNiel cousin:

STR Level STR Matches STR Matches Who Took the Big Y % STR Who Took Big Y STR Matches Who Also Match on the Big Y
12 5988 796 13 52
25 6660 725 11 57
37 878 94 11 12
67 1225 252 21 23
111 4 2 50 1

Typically, one would expect that all STR matches that took the Big Y would match on the Big Y, since STR results suggest relationships closer in time, but that’s not the case.

  • Many STR testers who have taken the Big Y seem to be just slightly too distant to be considered a Big Y match using SNPs, which flies in the face of conventional wisdom.
  • However, this could easily be a function of the fact that STRs mutate both backward and forwards and may have simply “happened” to have mutated to a common value – which suggests a closer relationship than actually exists.
  • It could also be that the SNP matching threshold needs to be raised since the enhanced and enriched Big Y-700 technology now finds more mutations than the older Big Y-500. I would like to see SNP matching expanded to 40 from 30 because it seems that clan connections may be being missed. Thirty may have been a great threshold before the more sensitive Big Y-700 test revealed more mutations, which means that people hit that 30 threshold before they did with previous tests.
  • Between the combination of STRs and SNPs mutating at the same time, some Big Y matches are pushed just out of range.

In a nutshell, the correlation I expected to find in terms of matching between STR and Big Y testing is not what I found. Let’s take a look at what we discovered.

It’s worth noting that the analysis is easier if you are working together with at least your closest matches or have access via projects to at least some of their results. You can see common STR values to 111 in projects, such as surname projects. Project administrators can view more if project members have allowed access.

Unexpected Discoveries and Gotchas

While I did expect STR matches to also match on the Big Y, I don’t expect the Big Y matches to necessarily match on the STR tests. After all, the Big Y is testing for more deep-rooted history.

Only one of the McNiel Big Y matches also matches at all levels of STR testing. That’s not surprising since Big Y matching reaches further back in time than STR testing, and indeed, not all STR testers have taken a Big Y test.

Of my McNeill cousin’s closest Big Y matches, we find the following relative to STR matching.

Surname Ancestral Location Big Y Variant/SNP Difference STR Match Level
Scott 1565 in Buccleuch, Selkirkshire, Scotland 20 12, 25, 37, 67
McCollum Not listed 21 67 only
Glass 1618 in Banbridge, County Down, Ireland 23 12, 25, 67
McMichael 1720 County Antrim, Ireland 28 67 only
Murphy Not listed 29 12, 25, 37, 67
Campbell Scotland 30 12, 25, 37, 67, 111

It’s ironic that the man who matches on all STR levels has the most variants, 30 – so many that with 1 more, he would not have been considered a Big Y match at all.

Only the Campbell man matches on all STR panels. Unfortunately, this Campbell male does not match the Clan Campbell line, so that momentary clan connection theory is immediately put to rest.

Block Tree Matches – What They Do, and Don’t, Mean

Note that a Carnes male, the other person who matches my McNeill cousin at 111 STR markers and has taken a Big Y test does not match at the Big Y level. His haplogroup BY69003 is located several branches up the tree, with our common ancestor, R-S588, having lived about 2000 years ago. Interestingly, we do match other R-S588 men.

This is an example where the total number of SNP mutations is greater than 30 for these 2 men (McNeill and Carnes), but not for my McNeill cousin compared with other men on the same S588 branch.

McNiel Big Y BY69003

By searching for Carnes on the block tree, I can view my cousin’s match to Mr. Carnes, even though they don’t match on the Big Y. STR matches who have taken the Big Y test, even if they don’t match at the Big Y level, are shown on the Block Tree on their branch.

By clicking on the haplogroup name, R-BY69003, above, I can then see three categories of information about the matches at that haplogroup level, below.

McNiel Big Y STR differences

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By selecting “Matches,” I can see results under the column, “Big Y.” This does NOT mean that the tester matches either Mr. Carnes or Mr. Riker on the Big Y, but is telling me that there are 14 differences out of 615 STR markers above 111 markers for Mr. Carnes, and 8 of 389 for Mr. Riker.

In other words, this Big Y column is providing STR information, not indicating a Big Y match. You can’t tell one way or another if someone shown on the Block Tree is shown there because they are a Big Y match or because they are an STR match that shares the same haplogroup.

As a cautionary note, your STR matches that have taken the Big Y ARE shown on the block tree, which is a good thing. Just don’t assume that means they are Big Y matches.

The 30 SNP threshold precludes some matches.

My research indicates that the people who match on STRs and carry the same haplogroup, but don’t match at the Big Y level, are every bit as relevant as those who do match on the Big Y.

McNIel Big Y block tree menu

If you’re not vigilant when viewing the block tree, you’ll make the assumption that you match all of the people showing on the Block Tree on the Big Y test since Block Tree appears under the Big Y tools. You have to check Big Y matches specifically to see if you match people shown on the Block Tree. You don’t necessarily match all of them on the Big Y test, and vice versa, of course.

You match Block Tree inhabitants either:

  • On the Big Y, but not the STR panels
  • On the Big Y AND at least one level of STRs between 12 and 111, inclusive
  • On STRs to someone who has taken the Big Y test, but whom you do not match on the Big Y test

Big Y-500 or Big Y-700?

McNiel Big Y STR differences

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Looking at the number of STR markers on the matches page of the Block Tree for BY69003, above, or on the STR Matches page is the only way to determine whether or not your match took the Big Y-700 or the Big Y-500 test.

If you add 111 to the Big Y SNP number of 615 for Mr. Carnes, the total equals 726, which is more than 700, so you know he took the Big Y-700.

If you add 111 to 389 for Mr. Riker, you get 500, which is less than 700, so you know that he took the Big Y-500 and not the Big Y-700.

There are still a very small number of men in the database who did not upgrade to 111 when they ordered their original Big Y test, but generally, this calculation methodology will work. Today, all Big Y tests are upgraded to 111 markers if they have not already tested at that level.

Why does Big Y-500 vs Big Y-700 matter? The enriched chemistry behind the testing technology improved significantly with the Big Y-700 test, enhancing Y-DNA results. I was an avowed skeptic until I saw the results myself after upgrading men in the Estes DNA project. In other words, if Big Y-500 testers upgrade, they will probably have more SNPs in common.

You may want to contact your closest Big Y-500 matches and ask if they will consider upgrading to the Big Y-700 test. For example, if we had close McNiel or similar surname matches, I would do exactly that.

Matching Both the Big Y and STRs – No Single Source

There is no single place or option to view whether or not you match someone BOTH on the Big Y AND STR markers. You can see both match categories individually, of course, but not together.

You can determine if your STR matches took the Big Y, below, and their haplogroup, which is quite useful, but you can’t tell if you match them at the Big Y level on this page.

McNiel Big Y STR match Big Y

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Selecting “Display Only Matches With Big Y” means displaying matches to men who took the Big Y test, not necessarily men you match on the Big Y. Mr. Conley, in the example above, does not match my McNeill cousin on the Big Y but does match him at 12 and 25 STR markers.

I hope FTDNA will add three display options:

  • Select only men that match on the Big Y in the STR panel
  • Add an option for Big Y on the advanced matches page
  • Indicate men who also match on STRs on the Big Y match page

It was cumbersome and frustrating to have to view all of the matches multiple times to compile various pieces of information in a separate spreadsheet.

No Big Y Match Download

There is also no option to download your Big Y matches. With a few matches, this doesn’t matter, but with 119 matches, or more, it does. As more people test, everyone will have more matches. That’s what we all want!

What you can do, however, is to download your STR matches from your match page at levels 12-111 individually, then combine them into one spreadsheet. (It would be nice to be able to download them all at once.)

McNiel Big Y csv

You can then add your Big Y matches manually to the STR spreadsheet, or you can simply create a separate Big Y spreadsheet. That’s what I chose to do after downloading my cousin’s 14,737 rows of STR matches. I told you that R-M222 was prolific! I wasn’t kidding.

This high number of STR matches also perfectly illustrates why the Big Y SNP results were so critical in establishing the backbone relationship structure. Using the two tools together is indispensable.

An additional benefit to downloading STR results is that you can sort the STR spreadsheet columns in surname order. This facilitates easily spotting all spelling variations of McNiel, including words like Niel, Neal and such that might be relevant but that you might not notice otherwise.

Creating a Big Y Spreadsheet

My McNiel cousin has 119 Big Y-700 matches.

I built a spreadsheet with the following columns facilitating sorting in a number of ways, with definitions as follows:

McNiel Big Y spreadsheet

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  • First Name
  • Last Name – You will want to search matches on your personal page at Family Tree DNA by this surname later, so be sure if there is a hyphenated name to enter it completely.
  • Haplogroup – You’ll want to sort by this field.
  • Convergent – A field you’ll complete when doing your analysis. Convergence is the common haplogroup in the tree shared by you and your match. In the case of the green matches above, which are color-coded on my spreadsheet to indicate the closest matches with my McNiel cousin, the convergent haplogroup is BY18350.
  • Common Tree Gen – This column is the generations on the Block Tree shown to this common haplogroup. In the example above, it’s between 9 and 14 SNP generations. I’ll show you where to gather this information.
  • Geographic Location – Can be garnered from 4 sources. No color in that cell indicates that this information came from the Earliest Known Ancestor (EKA) field in the STR matches. Blue indicates that I opened the tree and pulled the location information from that source. Orange means that someone else by the same surname whom the tester also Y DNA matches shows this location. I am very cautious when assigning orange, and it’s risky because it may not be accurate. A fourth source is to use Ancestry, MyHeritage, or another genealogical resource to identify a location if an individual provides genealogical information but no location in the EKA field. Utilizing genealogy databases is only possible if enough information is provided to make a unique identification. John Smith 1700-1750 won’t do it, but Seamus McDougal (1750-1810) married to Nelly Anderson might just work.
  • STR Match – Tells me if the Big Y match also matches on STR markers, and if so, which ones. Only the first 111 markers are used for matching. No STR match generally means the match is further back in time, but there are no hard and fast rules.
  • Big Y Match – My original goal was to combine this information with the STR match spreadsheet. If you don’t wish to combine the two, then you don’t need this column.
  • Tree – An easy way for me to keep track of which matches do and do not have a tree. Please upload or create a tree.

You can also add a spreadsheet column for comments or contact information.

McNiel Big Y profile

You will also want to click your match’s name to display their profile card, paying particular attention to the “About Me” information where people sometimes enter genealogical information. Also, scan the Ancestral Surnames where the match may enter a location for a specific surname.

Private Variants

I added additional spreadsheet columns, not shown above, for Private Variant analysis. That level of analysis is beyond what most people are interested in doing, so I’m only briefly discussing this aspect. You may want to read along, so you at least understand what you are looking at.

Clicking on Private Variants in your Big Y Results shows your variants, or mutations, that are unnamed as SNPs. When they are named, they become SNPs and are placed on the haplotree.

The reference or “normal” state for the DNA allele at that location is shown as the “Reference,” and “Genotype” is the result of the tester. Reference results are not shown for each tester, because the majority are the same. Only mutations are shown.

McNiel Big Y private variants

There are 5 Private Variants, total, for my cousin. I’ve obscured the actual variant numbers and instead typed in 111111 and 222222 for the first two as examples.

McNiel Big Y nonmatching variants

In our example, there are 6 Big Y matches, with matches one and five having the non-matching variants shown above.

Non-matching variants mean that the match, Mr. Scott, in example 1, does NOT match the tester (my cousin) on those variants.

  • If the tester (you) has no mutation, you won’t have a Private Variant shown on your Private Variant page.
  • If the tester does have a Private Variant shown, and that variant shows ON their matches list of non-matching variants, it means the match does NOT match the tester, and either has the normal reference value or a different mutation. Explained another way, if you have a mutation, and that variant is listed on your match list of Non-Matching Variants, your match does NOT match you and does NOT have the same mutation.
  • If the match does NOT have the Private Variant on their list, that means the match DOES match the tester, and they both have the same mutation, making this Private Variant a candidate to be named as a new SNP.
  • If you don’t have a Private Variant listed, but it shows in the Non-Matching Variants of your match, that means you have the reference or normal value, and they have a mutation.

In example #1, above, the tester has a mutation at variant 111111, and 111111 is shown as a Non-Matching Variant to Mr. Scott, so Mr. Scott does NOT match the tester. Mr. Scott also does NOT match the tester at locations 222222 and 444444.

In example #5, 111111 is NOT shown on the Non-Matching Variant list, so Mr. Treacy DOES match the tester.

I have a terrible time wrapping my head around the double negatives, so it’s critical that I make charts.

On the chart below, I’ve listed the tester’s private variants in an individual column each, so 111111, 222222, etc.

For each match, I’ve copy and pasted their Non-Matching Variants in a column to the right of the tester’s variants, in the lavender region. In this example, I’ve typed the example variants into separate columns for each tester so you can see the difference. Remember, a non-matching variant means they do NOT match the tester’s mutation.

McNiel private variants spreadsheet

On my normal spreadsheet where the non-matching variants don’t have individuals columns, I then search for the first variant, 111111. If the variant does appear in the list, it means that match #1 does NOT have the mutation, so I DON’T put an X in the box for match #1 under 111111.

In the example above, the only match that does NOT have 111111 on their list of Non-Matching Variants is #5, so an X IS placed in that corresponding cell. I’ve highlighted that column in yellow to indicate this is a candidate for a new SNP.

You can see that no one else has the variant, 222222, so it truly is totally private. It’s not highlighted in yellow because it’s not a candidate to be a new SNP.

Everyone shares mutation 333333, so it’s a great candidate to become a new SNP, as is 555555.

Match #6 shares the mutation at 444444, but no one else does.

This is a manual illustration of an automated process that occurs at Family Tree DNA. After Big Y matches are returned, automated software creates private variant lists of potential new haplogroups that are then reviewed internally where SNPs are evaluated, named, and placed on the tree if appropriate.

If you follow this process and discover matches, you probably don’t need to do anything, as the automated review process will likely catch up within a few days to weeks.

Big Y Matches

In the case of the McNiel line, it was exciting to discover several private variants, mutations that were not yet named SNPs, found in several matches that were candidates to be named as SNPs and placed on the Y haplotree.

Sure enough, a few days later, my McNeill cousin had a new haplogroup assignment.

Most people have at least one Private Variant, locations in which they do NOT match another tester. When several people have these same mutations, and they are high-quality reads, the Private Variant qualifies to be added to the haplotree as a SNP, a task performed at FamilyTreeDNA by Michael Sager.

If you ever have the opportunity to hear Michael speak, please do so. You can watch Michael’s presentation at Genetic Genealogy Ireland (GGI) titled “The Tree of Mankind,” on YouTube, here, compliments of Maurice Gleeson who coordinates GGI. Maurice has also written about the Gleeson Y DNA project analysis, here.

As a result of Cousin McNeill’s test, six new SNPs have been added to the Y haplotree, the tree of mankind. You can see our new haplogroup for our branch, BY18332, with an equivalent SNP, BY25938, along with three sibling branches to the left and right on the tree.

McNiel Big Y block tree 4 branch

Big Y testing not only answers genealogical questions, it advances science by building out the tree of mankind too.

The surname of the men who share the same haplogroup, R-BY18332, meaning the named SNP furthest down the tree, are McCollum and Campbell. Not what I expected. I expected to find a McNeil who does match on at least some STR markers. This is exactly why the Big Y is so critical to define the tree structure, then use STR matches to flesh it out.

Taking the Big Y-700 test provided granularity between 6 matches, shown above, who were all initially assigned to the same branch of the tree, BY18350, but were subsequently divided into 4 separate branches. My McNiel cousin is no longer equally as distant from all 6 men. We now know that our McNiel line is genetically closer on the Y chromosome to Campbell and McCollum and further distant from Murphy, Scott, McMichael, and Glass.

Not All SNP Matches are STR Matches

Not all SNP matches are also STR matches. Some relationships are too far back in time. However, in this case, while each person on the BY18350 branches matches at some STR level, only the Campbell individual matches at all STR levels.

Remember that variants (mutations) are accumulating down both respective branches of the tree at the same time, meaning one per roughly every 100 years (if 100 is the average number we want to use) for both testers. A total of 30 variants or mutations difference, an average of 15 on each branch of the tree (McNiel and their match) would suggest a common ancestor about 1500 years ago, so each Big Y match should have a common ancestor 1500 years ago or closer. At least on average, in theory.

The Big Y test match threshold is 30 variants, so if there were any more mismatches with the Campbell male, they would not have been a Big Y match, even though they have the exact same haplogroup.

Having the same haplogroup means that their terminal SNP is identical, the SNP furthest down the tree today, at least until someone matches one of them on their Private Variants (if any remain unnamed) and a new terminal SNP is assigned to one or both of them.

Mutations, and when they happen, are truly a roll of the dice. This is why viewing all of your Big Y Block Tree matches is critical, even if they don’t show on your Big Y match list. One more variant and Campbell would have not been shown as a match, yet he is actually quite close, on the same branch, and matches on all STR panels as well.

SNPs Establish the Backbone Structure

I always view the block tree first to provide a branching tree structure, then incorporate STR matches into the equation. Both can equally as important to genealogy, but haplogroup assignment is the most accurate tool, regardless of whether the two individuals match on the Big Y test, especially if the haplogroups are relatively close.

Let’s work with the Block Tree.

The Block Tree

McNIel Big Y block tree menu

Clicking on the link to the Block Tree in the Big Y results immediately displays the tester’s branch on the tree, below.

McNiel Big Y block tree descent

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On the left side are SNP generation markers. Keep in mind that approximate SNP generations are marked every 5 generations. The most recent generations are based on the number of private variants that have not yet been assigned as branches on the tree. It’s possible that when they are assigned that they will be placed upstream someplace, meaning that placement will reduce the number of early branches and perhaps increase the number of older branches.

The common haplogroup of all of the branches shown here with the upper red arrow is R-BY3344, about 15 SNP generations ago. If you’re using 100 years per SNP generation, that’s about 1500 years. If you’re using 80 years, then 1200 years ago. Some people use even fewer years for calculations.

If some of the private variants in the closer branches disappear, then the common ancestral branch may shift to closer in time.

This tree will always be approximate because some branches can never be detected. They have disappeared entirely over time when no males exist to reproduce.

Conversely, subclades have been born since a common ancestor clade whose descendants haven’t yet tested. As more people test, more clades will be discovered.

Therefore, most recent common ancestor (MRCA) haplogroup ages can only be estimated, based on who has tested and what we know today. The tree branches also vary depending on whether testers have taken the Big Y-500 or the more sensitive Big Y-700, which detects more variants. The Y haplotree is a combination of both.

Big Y-500 results will not be as granular and potentially do not position test-takers as far down the tree as Big Y-700 results would if they upgraded. You’ll need to factor that into your analysis if you’re drawing genealogical conclusions based on these results, especially close results.

You’ll note that the direct path of descent is shown above with arrows from BY3344 through the first blue box with 5 equivalent SNPS, to the next white box, our branch, with two equivalent SNPs. Our McNeil ancestor, the McCollum tester, and the Campell tester have no unresolved private variants between them, which suggests they are probably closer in time than 10 generations back. You can see that the SNP generations are pushed “up” by the neighbor variants.

Because of the fact that private variants don’t occur on a clock cycle and occur in individual lines at an unsteady rate, we must use averages.

That means that when we look further “up” the tree, clicking generation by generation on the up arrow above BY3344, the SNP generations on the left side “adjust” based on what is beneath, and unseen at that level.

The Block Tree Adjusts

Note, in the example above, BY3344 is at SNP generation 15.

Next, I clicked one generation upstream, to R-S668.

McNiel Big Y block tree S668

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You can see that S668 is about 21 SNP generations upstream, and now BY3344 is listed as 20 generations, not 15. You can see our branch, BY3344, but you can no longer see subclades or our matches below that branch in this view.

You can, however, see two matches that descend through S668, brother branches to BY3344, red arrows at far right.

Clicking on the up arrow one more time shows us haplogroup S673, below, and the child branches. The three child branches on which the tester has matches are shown with red arrows.

McNiel Big Y S673

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You’ll immediately notice that now S668 is shown at 19 SNP generations, not 20, and S673 is shown at 20. This SNP generation difference between views is a function of dealing with aggregated and averaged private variants on combined lines and causes the SNP generations to shift. This is also why I always say “about.”

As you continue to click up the tree, the shifting SNP generations continue, reminding us that we can’t truly see back in time. We can only achieve approximations, but those approximations improve as more people test, and more SNPs are named and placed in their proper places on the phylotree.

I love the Block Tree, although I wish I could see further side-to-side, allowing me to view all of the matches on one expanded tree so I can easily see their relationships to the tester, and each other.

Countries and Origins

In addition to displaying shared averaged autosomal origins of testers on a particular branch, if they have taken the Family Finder test and opted-in to sharing origins (ethnicity) results, you can also view the countries indicated by testers on that branch along with downstream branches of the tree.

McNiel Big Y countries

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For example, the Countries tab for S673 is shown above. I can see matches on this branch with no downstream haplogroup currently assigned, as well as cumulative results from downstream branches.

Still, I need to be able to view this information in a more linear format.

The Block Tree and spreadsheet information beautifully augment the haplotree, so let’s take a look.

The Haplotree

On your Y DNA results page, click on the “Haplotree and SNPs” link.

McNIel Big Y haplotree menu

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The Y haplotree will be displayed in pedigree style, quite familiar to genealogists. The SNP legend will be shown at the top of the display. In some cases, “presumed positive” results occur where coverage is lacking, back mutations or read errors are encountered. Presumed positive is based on positive SNPs further down the tree. In other words, that yellow SNP below must read positive or downstream ones wouldn’t.

McNIel Big Y pedigree descent

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The tester’s branch is shown with the grey bar. To the right of the haplogroup-defining SNP are listed the branch and equivalent SNP names. At far right, we see the total equivalent SNPs along with three dots that display the Country Report. I wish the haplotree also showed my matches, or at least my matching surnames, allowing me to click through. It doesn’t, so I have to return to the Big Y page or STR Matches page, or both.

I’ve starred each branch through which my McNiell cousin descends. Sibling branches are shown in grey. As you’ll recall from the Block Tree, we do have matches on those sibling branches, shown side by side with our branch.

The small numbers to the right of the haplogroup names indicate the number of downstream branches. BY18350 has three, all displayed. But looking upstream a bit, we see that DF97 has 135 downstream branches. We also have matches on several of those branches. To show those branches, simply click on the haplogroup.

The challenge for me, with 119 McNeill matches, is that I want to see a combination of the block tree, my spreadsheet information, and the haplotree. The block tree shows the names, my spreadsheet tells me on which branches to look for those matches. Many aren’t easily visible on the block tree because they are downstream on sibling branches.

Here’s where you can find and view different pieces of information.

Data and Sources STR Matches Page Big Y Matches Page Block Tree Haplogroups & SNPs Page
STR matches Yes No, but would like to see who matches at which STR levels If they have taken Big Y test, but doesn’t mean they match on Big Y matching No
SNP matches *1 Shows if STR match has common haplogroup, but not if tester matches on Big Y No, but would like to see who matches at which STR level Big Y matches and STR matches that aren’t Big Y matches are both shown No, but need this feature – see combined haplotree/ block tree
Other Haplogroup Branch Residents Yes, both estimated and tested No, use block tree or click through to profile card, would like to see haplogroup listed for Big Y matches Yes, both Big Y and STR tested, not estimated. Cannot tell if person is Big Y match or STR match, or both. No individuals, but would like that as part of countries report, see combined haplotree/block tree
Fully Expanded Phylotree No No Would like ability to see all branches with whom any Big Y or STR match resides at one time, even if it requires scrolling Yes, but no match information. Matches report could be added like on Block Tree.
Averaged Ethnicities if Have FF Test No No Yes, by haplogroup branch No
Countries Matches map STR only No, need Big Y matches map Yes Yes
Earliest Known Ancestor Yes No, but can click through to profile card No No
Customer Trees Yes No, need this link No No
Profile Card Yes, click through Yes, click through Yes, click through No match info on this page
Downloadable data By STR panel only, would like complete download with 1 click, also if Big Y or FF match Not available at all No No
Path to common haplogroup No No, but would like to see matches haplogroup and convergent haplogroup displayed No, would like the path to convergent haplogroup displayed as an option No, see combined match-block -haplotree in next section

*1 – the best way to see the haplogroup of a Big Y match is to click on their name to view their profile card since haplogroup is not displayed on the Big Y match page. If you happen to also match on STRs, their haplogroup is shown there as well. You can also search for their name using the block tree search function to view their haplogroup.

Necessity being the mother of invention, I created a combined match/block tree/haplotree.

And I really, REALLY hope Family Tree DNA implements something like this because, trust me, this was NOT fun! However, now that it’s done, it is extremely useful. With fewer matches, it should be a breeze.

Here are the steps to create the combined reference tree.

Combo Match/Block/Haplotree

I used Snagit to grab screenshots of the various portions of the haplotree and typed the surnames of the matches in the location of our common convergent haplogroup, taken from the spreadsheet. I also added the SNP generations in red for that haplogroup, at far left, to get some idea of when that common ancestor occurred.

McNIel Big Y combo tree

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This is, in essence, the end-goal of this exercise. There are a few steps to gather data.

Following the path of two matches (the tester and a specific match) you can find their common haplogroup. If your match is shown on the block tree in the same view with your branch, it’s easy to see your common convergent parent haplogroup. If you can’t see the common haplogroup, it’s takes a few extra steps by clicking up the block tree, as illustrated in an earlier section.

We need the ability to click on a match and have a tree display showing both paths to the common haplogroup.

McNiel Big Y convergent

I simulated this functionality in a spreadsheet with my McNiel cousin, a Riley match, and an Ocain match whose terminal SNP is the convergent SNP (M222) between Riley and McNiel. Of course, I’d also like to be able to click to see everyone on one chart on their appropriate branches.

Combining this information onto the haplotree, in the first image, below, M222, 4 men match my McNeill cousin – 2 who show M222 as their terminal SNP, and 2 downstream of M222 on a divergent branch that isn’t our direct branch. In other words, M222 is the convergence point for all 4 men plus my McNeill cousin.

McNiel Big Y M222 haplotree

click to enlarge

In the graphic below, you can see that M222 has a very large number of equivalent SNPs, which will likely become downstream haplogroups at some point in the future. However, today, these equivalent SNPs push M222 from 25 generations to 59. We’ll discuss how this meshes with known history in a minute.

McNiel Big Y M222 block tree

click to enlarge

Two men, Ocain and Ransom, who have both taken the Big Y, whose terminal SNP is M222, match my McNiel cousin. If their common ancestor was actually 59 generations in the past, it’s very, very unlikely that they would match at all given the 30 mutation threshold.

On my reconstructed Match/Block/Haplotree, I included the estimated SNP generations as well. We are starting with the most distant haplogroups and working our way forward in time with the graphics, below.

Make no mistake, there are thousands more men who descend from M222 that have tested, but all of those men except 4 have more than 30 mutations total, so they are not shown as Big Y matches, and they are not shown individually on the Block Tree because they neither match on the Big Y or STR tests. However, there is a way to view information for non-matching men who test positive for M222.

McNiel Big Y M222 countries

click to enlarge

Looking at the Block Tree for M222, many STR match men took a SNP test only to confirm M222, so they would be shown positive for the M222 SNP on STR results and, therefore, in the detailed view of M222 on the Block tree.

Haplogroup information about men who took the M222 test and whom the tester doesn’t match at all are shown here as well in the country and branch totals for R-M222. Their names aren’t displayed because they don’t match the tester on either type of Y DNA test.

Back to constructing my combined tree, I’ve left S658 in both images, above and below, as an overlap placeholder, as we move further down, or towards current, on the haplotree.

McNiel Big Y combo tree center

click to enlarge

Note that BY18350, above, is also an overlap connecting below.

You’ll recall that as a result of the Big Y test, BY18350 was split and now has three child branches plus one person whose terminal SNP is BY18350. All of the men shown below were on one branch until Big Y results revealed that BY18350 needed to be split, with multiple new haplogroups added to the tree.

McNiel Big Y combo tree current

click to enlarge

Using this combination of tools, it’s straightforward for me to see now that our McNiel line is closest to the Campbell tester from Scotland according to the Big Y test + STRs.

Equal according to the Big Y test, but slightly more distant, according to STR matching, is McCollum. The next closest would be sibling branches. Then in the parent group of the other three, BY18350, we find Glass from Scotland.

In BY18350 and subgroups, we find several Scotland locations and one Northern Ireland, which was likely from Scotland initially, given the surname and Ulster Plantation era.

The next upstream parent haplogroup is BY3344, which looks to be weighted towards ancestors from Scotland, shown on the country card, below.

McNiel Big Y BY3344

click to enlarge

This suggests that the origins of the McNiel line was, perhaps, in Scotland, but it doesn’t tell us whether or not George and presumably, Thomas, immigrated from Ireland or Scotland.

This combined tree, with SNPs, surnames from Big Y matches, along with Country information, allows me to see who is really more closely related and who is further away.

What I didn’t do, and probably should, is to add in all of the STR matches who have taken the Big Y test, shown on their convergent branch – but that’s just beyond the scope of time I’m willing to invest, at least for now, given that hundreds of STR matches have taken the Big Y test, and the work of building the combined tree is all manual today.

For those reading this article without access to the Y phylogenetic tree, there’s a public version of the Y and mitochondrial phylotrees available, here.

What About Those McNiels?

No other known McNiel descendants from either Thomas or George have taken the Big Y test, so I didn’t expect any to match, but I am interested in other men by similar surnames. Does ANY other McNiel have a Big Y match?

As it turns out, there are two, plus one STR match who took a Big Y test, but is not a Big Y match.

However, as you can see on the combined match/block/haplotree, above, the closest other Big Y-matching McNeil male is found at about 19 SNP generations, or roughly 1900 years ago. Even if you remove some of the variants in the lower generations that are based on an average number of individual variants, you’re still about 1200 years in the past. It’s extremely doubtful that any surname would survive in both lines from the year 800 or so.

That McNeil tester’s ancestor was born in 1747 in Tranent, Scotland.

The second Big Y-matching person is an O’Neil, a few branches further up in the tree.

The convergent SNP of the two branches, meaning O’Neil and McNeill are at approximately the 21 generation level. The O’Neil man’s Neill ancestor is found in 1843 in Cookestown, County Tyrone, Ireland.

McNiel Big Y convergent McNeil lines

I created a spreadsheet showing convergent lines:

  • The McNeill man with haplogroup A4697 (ancestor Tranent, Scotland) is clearly closest genetically.
  • O’Neill BY91591, who is brother clades with Neel and Neal, all Irish, is another Big Y match.
  • The McNeill man with haplogroup FT91182 is an STR match, but not a Big Y match.

The convergent haplogroup of all of these men is DF105 at about the 22 SNP generation marker.

STRs

Let’s turn back to STR tests, with results that produce matches closer in time.

Searching my STR download spreadsheet for similar surnames, I discovered several surname matches, mining the Earliest Known Ancestor information, profiles and trees produced data as follows:

Ancestor STR Match Level Location
George Charles Neil 12, 25, match on Big Y A4697 1747-1814 Tranent, Scotland
Hugh McNeil 25 (tested at 67) Born 1800 Country Antrim, Northern Ireland
Duncan McNeill 12 (tested at 111) Married 1789, Argyllshire, Scotland
William McNeill 12, 25 (tested at 37) Blackbraes, Stirlingshire, Scotland
William McNiel 25 (tested at 67) Born 1832 Scotland
Patrick McNiel 25 (tested at 111) Trien East, County Roscommon, Ireland
Daniel McNeill 25 (tested at 67) Born 1764 Londonderry, Northern Ireland
McNeil 12 (tested at 67) 1800 Ireland
McNeill (2 matches) 25 (tested Big Y-  SNP FT91182) 1810, Antrim, Northern Ireland
Neal 25 – (tested Big Y, SNP BY146184) Antrim, Northern Ireland
Neel (2 matches) 67 (tested at 111, and Big Y) 1750 Ireland, Northern Ireland

Our best clue that includes a Big Y and STR match is a descendant of George Charles Neil born in Tranent, Scotland, in 1747.

Perhaps our second-best clue comes in the form of a 111 marker match to a descendant of one Thomas McNeil who appears in records as early as 1753 and died in 1761 In Rombout Precinct, Dutchess County, NY where his son John was born. This line and another match at a lower level both reportedly track back to early New Hampshire in the 1600s.

The MacNeil DNA Project tells us the following:

Participant 106370 descends from Isaiah McNeil b. 14 May 1786 Schaghticoke, Rensselaer Co. NY and d. 28 Aug 1855 Poughkeepsie, Dutchess Co., NY, who married Alida VanSchoonhoven.

Isaiah’s parents were John McNeal, baptized 21 Jun 1761 Rombout, Dutchess Co., NY, d. 15 Feb 1820 Stillwater, Saratoga Co., NY and Helena Van De Bogart.

John’s parents were Thomas McNeal, b.c. 1725, d. 14 Aug 1761 NY and Rachel Haff.

Thomas’s parents were John McNeal Jr., b. around 1700, d. 1762 Wallkill, Orange Co., NY (now Ulster Co. formed 1683) and Martha Borland.

John’s parents were John McNeal Sr. and ? From. It appears that John Sr. and his family were this participant’s first generation of Americans.

Searching this line on Ancestry, I discovered additional information that, if accurate, may be relevant. This lineage, if correct, and it may not be, possibly reaching back to Edinburgh, Scotland. While the information gathered from Ancestry trees is certainly not compelling in and of itself, it provides a place to begin research.

Unfortunately, based on matches shown on the MacNeil DNA Project public page, STR marker mutations for kits 30279, B78471 and 417040 when compared to others don’t aid in clustering or indicating which men might be related to this group more closely than others using line-marker mutations.

Matches Map

Let’s take a look at what the STR Matches Map tells us.

McNiel Big Y matches map menu

This 67 marker Matches Map shows the locations of the earliest known ancestors of STR matches who have entered location information.

McNiel Big Y matches mapMcNiel Big Y matches map legend

My McNeill cousin’s closest matches are scattered with no clear cluster pattern.

Unfortunately, there is no corresponding map for Big Y matches.

SNP Map

The SNP map provided under the Y DNA results allows testers to view the locations where specific haplogroups are found.

McNiel Big Y SNP map

The SNP map marks an area where at least two or more people have claimed their most distant known ancestor to be. The cluster size is the maximum amount of miles between people that is allowed in order for a marker indicating a cluster at a location to appear. So for example, the sample size is at least 2 people who have tested, and listed their most distant known ancestor, the cluster is the radius those two people can be found in. So, if you have 10 red dots, that means in 1000 miles there are 10 clusters of at least two people for that particular SNP. Note that these locations do NOT include people who have tested positive for downstream locations, although it does include people who have taken individual SNP tests.

Working my way from the McNiel haplogroup backward in time on the SNP map, neither BY18332 nor BY18350 have enough people who’ve tested, or they didn’t provide a location.

Moving to the next haplogroup up the tree, two clusters are formed for BY3344, shown below.

McNIel Big Y BY3344 map

S668, below.

McNiel Big Y S668 map

It’s interesting that one cluster includes Glasgow.

S673, below.

McNiel Big Y S673 map

DF85, below:

McNiel Big Y DF85 map

DF105 below:

McNiel BIg Y DF105 map

M222, below:

McNiel Big Y M222 map

For R-M222, I’ve cropped the locations beyond Ireland and Scotland. Clearly, RM222 is the most prevalent in Ireland, followed by Scotland. Wherever M222 originated, it has saturated Ireland and spread widely in Scotland as well.

R-M222

R-M222, the SNP initially thought to indicate Niall of the 9 Hostages, occurred roughly 25-59 SNP generations in the past. If this age is even remotely accurate, averaging by 80 years per generation often utilized for Big Y results, produces an age of 2000 – 4720 years. I find it extremely difficult to believe any semblance of a surname survived that long. Even if you reduce the time in the past to the historical narrative, roughly the year 400, 1600 years, I still have a difficult time believing the McNiel surname is a result of being a descendant of Niall of the 9 Hostages directly, although oral history does have staying power, especially in a clan setting where clan membership confers an advantage.

Surname or not, clearly, our line along with the others whom we match on the Big Y do descend from a prolific common ancestor. It’s very unlikely that the mutation occurred in Niall’s generation, and much more likely that other men carried M222 and shared a common ancestor with Niall at some point in the distant past.

McNiel Conclusion – Is There One?

If I had two McNiel wishes, they would be:

  • Finding records someplace in Virginia that connect George and presumably brothers Thomas and John to their parents.
  • A McNiel male from wherever our McNiel line originated becoming inspired to Y DNA test. Finding a male from the homeland might point the way to records in which I could potentially find baptismal records for George about 1720 and Thomas about 1724, along with possibly John, if he existed.

I remain hopeful for a McNiel from Edinburgh, or perhaps Glasgow.

I feel reasonably confident that our line originated genetically in Scotland. That likely precludes Niall of the 9 Hostages as a direct ancestor, but perhaps not. Certainly, one of his descendants could have crossed the channel to Scotland. Or, perhaps, our common ancestor is further back in time. Based on the maps, it’s clear that M222 saturates Ireland and is found widely in Scotland as well.

A great deal depends on the actual age of M222 and where it originated. Certainly, Niall had ancestors too, and the Ui Neill dynasty reaches further back, genetically, than their recorded history in Ireland. Given the density of M222 and spread, it’s very likely that M222 did, in fact, originate in Ireland or, alternatively, very early in Scotland and proliferated in Ireland.

If the Ui Neill dynasty was represented in the persona of the High King, Niall of the 9 Hostages, 1600 years ago, his M222 ancestors were clearly inhabiting Ireland earlier.

We may not be descended from Niall personally, but we are assuredly related to him, sharing a common ancestor sometime back in the prehistory of Ireland and Scotland. That man would sire most of the Irish men today and clearly, many Scots as well.

Our ancestors, whoever they were, were indeed in Ireland millennia ago. R-M222, our ancestor, was the ancestor of the Ui Neill dynasty and of our own Reverend George McNiel.

Our ancestors may have been at Knowth and New Grange, and yes, perhaps even at Tara.

Tara Niall mound in sun

Someplace in the mists of history, one man made a different choice, perhaps paddling across the channel, never to return, resulting in M222 descendants being found in Scotland. His descendants include our McNeil ancestors, who still slumber someplace, awaiting discovery.

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Concepts: Chromosome Browser – What Is It, How Do I Use It, and Why Do I Care?

The goal of genetic genealogy is to utilize DNA matches to verify known ancestors and identify unknown ancestors.

A chromosome browser is a tool that allows testers to visualize and compare their DNA on each chromosome with that of their genetic matches. How to utilize and interpret that information becomes a little more tricky.

I’ve had requests for one article with all the information in one place about chromosome browsers:

  • What they are
  • How and when to use them
  • Why you’d want to

I’ve included a feature comparison chart and educational resource list at the end.

I would suggest just reading through this article the first time, then following along with your own DNA results after you understand the basic landscape. Using your own results is the best way to learn anything.

What Does a Chromosome Browser Look Like?

Here’s an example of a match to my DNA at FamilyTreeDNA viewed on their chromosome browser.

browser example.png

On my first 16 chromosomes, shown above, my 1C1R (first cousin once removed,) Cheryl, matches me where the chromosomes are painted blue. My chromosome is represented by the grey background, and her matching portion by the blue overlay.

Cheryl matches me on some portion of all chromosomes except 2, 6, and 13, where we don’t match at all.

You can select any one person, like Cheryl, from your match list to view on a chromosome browser to see where they match you on your chromosomes, or you can choose multiple matches, as shown below.

browser multiple example.png

I selected my 7 closest matches that are not my immediate family, meaning not my parents or children. I’m the background grey chromosome, and each person’s match is painted on top of “my chromosome” in the location where they match me. You see 7 images of my grey chromosome 1, for example, because each of the 7 people being compared to me are shown stacked below one another.

Everyplace that Cheryl matches me is shown on the top image of each chromosome, and our matching segment is shown in blue. The same for the second red copy of the chromosome, representing Don’s match to me. Each person I’ve selected to match against is shown by their own respective color.

You’ll note that in some cases, two people match me in the same location. Those are the essential hints we are looking for. We’ll be discussing how to unravel, interpret, and use matches in the rest of this article.

browser MyHeritage example.png

The chromosome browser at MyHeritage looks quite similar. However, I have a different “top 7” matches because each vendor has people who test on their platform who don’t test or transfer elsewhere.

Each vendor that supports chromosome browsers (FamilyTreeDNA, MyHeritage, 23andMe, and GedMatch) provides their own implementation, of course, but the fundamentals of chromosome browsers, how they work and what they are telling us is universal.

Why Do I Need a Chromosome Browser?

“But,” you might say, “I don’t need to compare my DNA with my matches because the vendors already tell me that I match someone, which confirms that we are related and share a common ancestor.”

Well, not exactly. It’s not quite that straightforward.

Let’s take a look at:

  • How and why people match
  • What matches do and don’t tell you
  • Both with and without a chromosome browser

In part, whether you utilize a chromosome browser or not depends on which of the following you seek:

  • A broad-brush general answer; yes or no, I match someone, but either I don’t know how are related, or have to assume why. There’s that assume word again.
  • To actually confirm and prove your ancestry, getting every ounce of value out of your DNA test.

Not everyone’s goals are the same. Fortunately, we have an entire toolbox with a wide range of tools. Different tools are better suited for different tasks.

People seeking unknown parents should read the article, Identifying Unknown Parents and Individuals Using DNA Matching because the methodology for identifying unknown parents is somewhat different than working with genealogy. This article focuses on genealogy, although the foundation genetic principles are the same.

If you’re just opening your DNA results for the first time, the article, First Steps When Your DNA Results are Ready – Sticking Your Toe in the Genealogy Water would be a great place to start.

Before we discuss chromosome browsers further, we need to talk about DNA inheritance.

Your Parents

Every person has 2 copies of each of their 22 chromosomes – one copy contributed by their mother and one copy contributed by their father. A child receives exactly half of the autosomal DNA of each parent. The DNA of each parent combines somewhat randomly so that you receive one chromosome’s worth of DNA from each of your parents, which is half of each parent’s total.

On each chromosome, you receive some portion of the DNA that each parent received from their ancestors, but not exactly half of the DNA from each individual ancestor. In other words, it’s not sliced precisely in half, but served up in chunks called segments.

Sometimes you receive an entire segment of an ancestor’s DNA, sometimes none, and sometimes a portion that isn’t equal to half of your parent’s segment.

browser inheritance.png

This means that you don’t receive exactly half of the DNA of each of your grandparents, which would be 25% each. You might receive more like 22% from one maternal grandparent and 28% from the other maternal grandparent for a total of 50% of the DNA you inherit from your parents. The other 50% of your DNA comes from the other parent, of course. I wrote about that here.

There’s one tiny confounding detail. The DNA of your Mom and Dad is scrambled in you, meaning that the lab can’t discern scientifically which side is which and can’t tell which pieces of DNA came from Mom and which from Dad. Think of a genetic blender.

Our job, using genetic genealogy, is to figure out which side of our family people who match us descend from – which leads us to our common ancestor(s).

Parallel Roads

For the purposes of this discussion, you’ll need to understand that the two copies you receive of each chromosome, one from each parent, have the exact same “addresses.” Think of these as parallel streets or roads with identical addresses on each road.

browser street.png

In the example above, you can see Dad’s blue chromosome and Mom’s red chromosome as compared to me. Of course, children and parents match on the full length of each chromosome.

I’ve divided this chromosome into 6 blocks, for purposes of illustration, plus the centromere where we generally find no addresses used for genetic genealogy.

In the 500 block, we see that the address of 510 Main (red bar) could occur on either Dad’s chromosome, or Mom’s. With only an address and nothing more, you have no way to know whether your match with someone at 510 Main is on Mom’s or Dad’s side, because both streets have exactly the same addresses.

Therefore, if two people match you, at the same address on that chromosome, like 510 Main Street, they could be:

  • Both maternal matches, meaning both descended from your mother’s ancestors, and those two people will also match each other
  • Both paternal matches, meaning both descended from your father’s ancestors, and those two people will also match each other
  • One maternal and one paternal match, and those two people will not match each other

Well then, how do we know which side of the family a match descends from, and how do we know if we share a common ancestor?

Good question!

Identical by Descent

If you and another person match on a reasonably sized DNA segment, generally about 7 cM or above, your match is probably “identical by descent,” meaning not “identical by chance.” In this case, then yes, a match does confirm that you share a common ancestor.

Identical by descent (IBD) means you inherited the piece of DNA from a common ancestor, inherited through the relevant parent.

Identical by chance (IBC) means that your mom’s and dad’s DNA just happens to have been inherited by you randomly in a way that creates a sequence of DNA that matches that other person. I wrote about both IBD and IBC here.

MMB stats by cM 2

This chart, courtesy of statistician Philip Gammon, from the article Introducing the Match-Maker-Breaker Tool for Parental Phasing shows the percentage of time we expect matches of specific segment sizes to be valid, or identical by descent.

Identical by Chance

How does this work?

How is a match NOT identical by descent, meaning that it is identical by chance and therefore not a “real” or valid match, a situation also known as a false positive?

browser inheritance grid.png

The answer involves how DNA is inherited.

You receive a chromosome with a piece of DNA at every address from both parents. Of course, this means you have two pieces of DNA at each address. Therefore people will match you on either piece of DNA. People from your Dad’s side will match you on the pieces you inherited from him, and people from your Mom’s side will match you on the pieces you inherited from her.

However, both of those matches have the same address on their parallel streets as shown in the illustration, above. Your matches from your mom’s side will have all As, and those from your dad’s side will have all Ts.

The problem is that you have no way to know which pieces you inherited from Mom and from Dad – at least not without additional information.

You can see that for 10 contiguous locations (addresses), which create an example “segment” of your DNA, you inherited all As from your Mom and all Ts from your Dad. In order to match you, someone would either need to have an A or a T in one of their two inherited locations, because you have an A and a T, both. If the other person has a C or a G, there’s no match.

Your match inherited a specific sequence from their mother and father, just like you did. As you can see, even though they do match you because they have either an A or a T in all 10 locations – the As and Ts did not all descend from either their mother or father. Their random inheritance of Ts and As just happens to match you.

If your match’s parents have tested, you won’t match either of their parents nor will they match either of your parents, which tells you immediately that this match is by chance (IBC) and not by descent (IBD), meaning this segment did not come from a common ancestor. It’s identical by chance and, therefore, a false positive.

If We Match Someone Else In Common, Doesn’t That Prove Identical by Descent?

Nope, but I sure wish it did!

The vendors show you who else you and your match both match in common, which provides a SUGGESTION as to your common ancestor – assuming you know which common ancestor any of these people share with you.

browser icw.png

However, shared matches are absolutely NOT a guarantee that you, your match, and your common matches all share the same ancestor, unless you’re close family. Your shared match could match you or your match through different ancestors – or could be identical by chance.

How can we be more confident of what matching is actually telling us?

How can we sort this out?

Uncertainties and Remedies

Here’s are 9 things you DON’T know, based on matching alone, along with tips and techniques to learn more.

  1. If your match to Person A is below about 20cM, you’ll need to verify that it’s a legitimate IBD match (not IBC). You can achieve this by determining if Person A also matches one of your parents and if you match one of Person A’s parents, if parents have tested.

Not enough parents have tested? An alternative method is by determining if you and Person A both match known descendants of the candidate ancestors ON THE SAME SEGMENT. This is where the chromosome browser enters the picture.

In other words, at least three people who are confirmed to descend from your presumptive common ancestor, preferably through at least two different children, must match on a significant portion of the same segment.

Why is that? Because every segment has its own unique genealogical history. Each segment can and often does lead to different ancestors as you move further back in time.

In this example, I’m viewing Buster, David, and E., three cousins descended from the same ancestral couple, compared to me on my chromosome browser. I’m the background grey, and they show in color. You can see that all three of them match me on at least some significant portion of the same segment of chromosome 15.

browser 3 cousins.png

If those people also match each other, that’s called triangulation. Triangulation confirms descent from a common ancestral source.

In this case, I already know that these people are related on my paternal side. The fact that they all match my father’s DNA and are therefore all automatically assigned to my paternal matching tab at Family Tree DNA confirms my paper-trail genealogy.

I wrote detailed steps for triangulation at Family Tree DNA, here. In a nutshell, matching on the same segment to people who are bucketed to the same parent is an automated method of triangulation.

Of course, not everyone has the luxury of having their parents tested, so testing other family members, finding common segments, and assigning people to their proper location in your tree facilitates confirmation of your genealogy (and automating triangulation.)

The ONLY way you can determine if people match you on the same segment, and match each other, is having segment information available to you and utilizing a chromosome browser.

browser MyHeritage triangulation.png

In the example above, the MyHeritage triangulation tool brackets matches that match you (the background grey) and who are all triangulated, meaning they all also match each other. In this case, the portion where all three people match me AND each other is bracketed. I wrote about triangulation at MyHeritage here.

  1. If you match several people who descend from the same ancestor, John Doe, for example, on paper, you CANNOT presume that your match to all of those people is due to a segment of DNA descended from John Doe or his wife. You may not match any of those people BECAUSE OF or through segments inherited from John Doe or his wife. You need segment information and a chromosome browser to view the location of those matches.

Assuming these are legitimate IBD matches, you may share another common line, known or unknown, with some or all of those matches.

It’s easy to assume that because you match and share matches in common with other people who believe they are descended from that same ancestor:

  • That you’re all matching because of that ancestor.
  • Even on the same segments.

Neither of those presumptions can be made without additional information.

Trust me, you’ll get yourself in a heap o’ trouble if you assume. Been there, done that. T-shirt was ugly.

Let’s look at how this works.

browser venn.png

Here’s a Venn diagram showing me, in the middle, surrounded by three of my matches:

  • Match 1 – Periwinkle, descends from Lazarus Estes and Elizabeth Vannoy
  • Match 2 – Teal, descends from Joseph Bolton and Margaret Claxton
  • Match 3 – Mustard, descends from John Y. Estes and Rutha Dodson

Utilizing a chromosome browser, autocluster software, and other tools, we can determine if those matches also match each other on a common segment, which means they triangulate and confirm common ancestral descent.

Of course, those people could match each other due to a different ancestor, not necessarily the one I share with them nor the ancestors I think we match through.

If they/we do all match because they descend from a common ancestor, they can still match each other on different segments that don’t match me.

I’m in the center. All three people match me, and they also match each other, shown in the overlap intersections.

Note that the intersection between the periwinkle (Match 1) and teal (Match 2) people, who match each other, is due to the wives of the children of two of my ancestors. In other words, their match to each other has absolutely nothing to do with their match to me. This was an “aha’ moment for me when I first realized this was a possibility and happens far more than I ever suspected.

The intersection of the periwinkle (Match 1) and mustard (Match 3) matches is due to the Dodson line, but on a different segment than they both share with me. If they had matched each other and me on the same segment, we would be all triangulated, but we aren’t.

The source of the teal (Match 2) to mustard (Match 3) is unknown, but then again, Match 3’s tree is relatively incomplete.

Let’s take a look at autocluster software which assists greatly with automating the process of determining who matches each other, in addition to who matches you.

  1. Clustering technology, meaning the Leeds method as automated by Genetic Affairs and DNAGedcom help, but don’t, by themselves, resolve the quandary of HOW people match you and each other.

People in a colored cluster all match you and each other – but not necessarily on the same segment, AND, they can match each other because they are related through different ancestors not related to your ancestor. The benefit of autocluster software is that this process is automated. However, not all of your matches will qualify to be placed in clusters.

browser autocluster.png

My mustard cluster above includes the three people shown in the chromosome browser examples – and 12 more matches that can be now be researched because we know that they are all part of a group of people who all match me, and several of whom match each other too.

My matches may not match each other for a variety of reasons, including:

  • They are too far removed in time/generations and didn’t inherit any common ancestral DNA.
  • This cluster is comprised of some people matching me on different (perhaps intermarried) lines.
  • Some may be IBC matches.

Darker grey boxes indicate that those people should be in both clusters, meaning the red and mustard clusters, because they match people in two clusters. That’s another hint. Because of the grid nature of clusters, one person cannot be associated with more than 2 clusters, maximum. Therefore, people like first cousins who are closely related to the tester and could potentially be in many clusters are not as useful in clusters as they are when utilizing other tools.

  1. Clusters and chromosome browsers are much less complex than pedigree charts, especially when dealing with many people. I charted out the relationships of the three example matches from the Venn diagram. You can see that this gets messy quickly, and it’s much more challenging to visualize and understand than either the chromosome browser or autoclusters.

Having said that, the ultimate GOAL is to identify how each person is related to you and place them in their proper place in your tree. This, cumulatively with your matches, is what identifies and confirms ancestors – the overarching purpose of genealogy and genetic genealogy.

Let’s take a look at this particular colorized pedigree chart.

Browser pedigree.png

click to enlarge

The pedigree chart above shows the genetic relationship between me and the three matches shown in the Venn diagram.

Four descendants of 2 ancestral couples are shown, above; Joseph Bolton and Margaret Claxton, and John Y. Estes and Rutha Dodson. DNA tells me that all 3 people match me and also match each other.

The color of the square (above) is the color of DNA that represents the DNA segment that I received and match with these particular testers. This chart is NOT illustrating how much DNA is passed in each generation – we already know that every child inherits half of the DNA of each parent. This chart shows match/inheritance coloring for ONE MATCHING SEGMENT with each match, ONLY.

Let’s look at Joseph Bolton (blue) and Margaret Claxton (pink). I descend through their daughter, Ollie Bolton, who married William George Estes, my grandfather. The DNA segment that I share with blue Match 2 (bottom left) is a segment that I inherited from Joseph Bolton (blue). I also carry inherited DNA from Margaret Claxton too, but that’s not the segment that I share with Match 2, which is why the path from Joseph Bolton to me, in this case, is blue – and why Match 2 is blue. (Just so you are aware, I know this segment descends from Joseph Bolton, because I also match descendants of Joseph’s father on this segment – but that generation/mtach is not shown on this pedigree chart.)

If I were comparing to someone else who I match through Margaret Claxton, I would color the DNA from Margaret Claxton to me pink in that illustration. You don’t have to DO this with your pedigree chart, so don’t worry. I created this example to help you understand.

The colored dots shown on the squares indicate that various ancestors and living people do indeed carry DNA from specific ancestors, even though that’s not the segment that matches a particular person. In other words, the daughter, Ollie, of Joseph Bolton and Margaret Claxton carries 50% pink DNA, represented by the pink dot on blue Ollie Bolton, married to purple William George Estes.

Ollie Bolton and William George Estes had my father, who I’ve shown as half purple (Estes) and half blue (Bolton) because I share Bolton DNA with Match 2, and Estes DNA with Match 1. Obviously, everyone receives half of each parent’s DNA, but in this case, I’m showing the path DNA descended for a specific segment shared with a particular match.

I’ve represented myself with the 5 colors of DNA that I carry from these particular ancestors shown on the pedigree chart. I assuredly will match other people with DNA that we’ve both inherited from these ancestors. I may match these same matches shown with DNA that we both inherited from other ancestors – for example, I might match Match 2 on a different segment that we both inherited from Margaret Claxton. Match 2 is my second cousin, so it’s quite likely that we do indeed share multiple segments of DNA.

Looking at Match 3, who knows very little about their genealogy, I can tell, based on other matches, that we share Dodson DNA inherited through Rutha Dodson.

I need to check every person in my cluster, and that I share DNA with on these same segment addresses to see if they match on my paternal side and if they match each other.

  1. At Family Tree DNA, I will be able to garner more information about whether or not my matches match each other by using the Matrix tool as well as by utilizing Phased Family Matching.

At Family Tree DNA, I determined that these people all match in common with me and Match 1 by using the “In Common With” tool. You can read more about how to use “In Common With” matching, here.

browser paternal.png

Family Matching phases the matches, assigning or bucketed them maternally or paternally (blue and red icons above), indicating, when possible, if these matches occur on the same side of your family. I wrote about the concept of phasing, here, and Phased Family Matching here and here.

Please note that there is no longer a limit on how distantly related a match can be in order to be utilized in Phased Family Matching, so long as it’s over the phase-matching threshold and connected correctly in your tree.

browser family tree dna link tree.png

Bottom line, if you can figure out how you’re related to someone, just add them into your tree by creating a profile card and link their DNA match to them by simply dragging and dropping, as illustrated above.

Linking your matches allows Family Matching to maternally or paternally assign other matches that match both you and your tree-linked matches.

If your matches match you on the same segment on the same parental side, that’s segment triangulation, assuming the matches are IBD. Phased Family Matching does this automatically for you, where possible, based on who you have linked in your tree.

For matches that aren’t automatically bucketed, there’s another tool, the Matrix.

browser matrix.png

In situations where your matches aren’t “bucketed” either maternally or paternally, the Matrix tool allows you to select matches to determine whether your matches also match each other. It’s another way of clustering where you can select specific people to compare. Note that because they also match each other (blue square) does NOT mean it’s on the same segment(s) where they match you. Remember our Venn diagram.

browser matrix grid.png

  1. Just because you and your matches all match each other doesn’t mean that they are matching each other because of the same ancestor. In other words, your matches may match each other due to another or unknown ancestor. In our pedigree example, you can see that the three matches match each other in various ways.
browser pedigree match.png

click to enlarge

  • Match 1 and Match 2 match each other because they are related through the green Jones family, who is not related to me.
  • Match 2 and Match 3 don’t know why they match. They both match me, but not on the same segment they share with each other.
  • Match 1 and Match 3 match through the mustard Dodson line, but not on the same segment that matches me. If we all did match on the same segment, we would be triangulated, but we wouldn’t know why Match 3 was in this triangulation group.
  1. Looking at a downloaded segment file of your matches, available at all testing vendors who support segment information and a chromosome browser, you can’t determine without additional information whether your matches also match each other.

browser chr 15.png

Here’s a group of people, above, that we’ve been working with on chromosome 15.

My entire match-list shows many more matches on that segment of chromosome 15. Below are just a few.

browser chr 15 all

Looking at seven of these people in the chromosome browser, we can see visually that they all overlap on part of a segment on chromosome 15. It’s a lot easier to see the amount of overlap using a browser as opposed to the list. But you can only view 7 at a time in the browser, so the combination of both tools is quite useful. The downloaded spreadsheet shows you who to select to view for any particular segment.

browser chr 15 compare.png

The critical thing to remember is that some matches will be from tyour mother’s side and some from your father’s side.

Without additional information and advanced tools, there’s no way to tell the difference – unless they are bucketed using Phased Family Matching at Family Tree DNA or bracketed with a triangulation bracket at MyHeritage.

At MyHeritage, this assumes you know the shared ancestor of at least one person in the triangulation group which effectively assigns the match to the maternal or paternal side.

Looking at known relatives on either side, and seeing who they also match, is how to determine whether these people match paternally or maternally. In this example below, the blue people are bucketed paternally through Phased Family Matching, the pink maternally, and the white rows aren’t bucketed and therefore require additional evaluation.

browser chr 15 maternal paternal.png

Additional research shows that Jonathan is a maternal match, but Robert and Adam are identical by chance because they don’t match either of my parents on this segment. They might be valid matches on other segments, but not this one.

browser chr 15 compare maternal paternal.png

  1. Utilizing relatives who have tested is a huge benefit, and why we suggest that everyone test their closest upstream relatives (meaning not children or grandchildren.) Testing all siblings is recommended if both parents aren’t available to test, because every child received different parts of their parents’ DNA, so they will match different relatives.

After deleting segments under 7 cM, I combine the segment match download files of multiple family members (who agree to allow me to aggregate their matches into one file for analysis) so that I can create a master match file for a particular family group. Sorting by match name, I can identify people that several of my cousins’ match.

browser 4 groups.png

This example is from a spreadsheet where I’ve combined the results of about 10 collaborating cousins to determine if we can break through a collective brick wall. Sorted by match name, this table shows the first 4 common matches that appear on multiple cousin’s match lists. Remember that how these people match may have nothing to do with our brick wall – or it might.

Note that while the 4 matches, AB, AG, ag, and A. Wayne, appear in different cousins’ match lists, only one shares a common segment of DNA: AB triangulates with Buster and Iona. This is precisely WHY you need segment information, and a chromosome browser, to visualize these matches, and to confirm that they do share a common DNA segment descended from a specific ancestor.

These same people will probably appear in autocluster groups together as well. It’s worth noting, as illustrated in the download example, that it’s much more typical for “in common with” matches to match on different segments than on the same segment. 

  1. Keep in mind that you will match both your mother and father on every single chromosome for the entire length of each chromosome.

browser parent matching.png

Here’s my kit matching with my father, in blue, and mother, in red on chromosomes 1 and 2.

Given that I match both of my parents on the full chromosome, inheriting one copy of my chromosome from each parent, it’s impossible to tell by adding any person at random to the chromosome browser whether they match me maternally or paternally. Furthermore, many people aren’t fortunate enough to have parents available for testing.

To overcome that obstacle, you can compare to known or close relatives. In fact, your close relatives are genetic genealogy gold and serve as your match anchor. A match that matches you and your close relatives can be assigned either maternally or paternally. I wrote about that here.

browser parent plus buster.png

You can see that my cousin Buster matches me on chromosome 15, as do both of my parents, of course. At this point, I can’t tell from this information alone whether Buster matches on my mother’s or father’s side.

I can tell you that indeed, Buster does match my father on this same segment, but what if I don’t have the benefit of my father’s DNA test?

Genealogy tells me that Buster matches me on my paternal side, through Lazarus Estes and Elizabeth Vannoy. Given that Buster is a relatively close family member, I already know how Buster and I are related and that our DNA matches. That knowledge will help me identify and place other relatives in my tree who match us both on the same segment of DNA.

To trigger Phased Family Matching, I placed Buster in the proper place in my tree at Family Tree DNA and linked his DNA. His Y DNA also matches the Estes males, so no adoptions or misattributed parental events have occurred in the direct Estes patrilineal line.

browser family tree dna tree.png

I can confirm this relationship by checking to see if Buster matches known relatives on my father’s side of the family, including my father using the “in common with” tool.

Buster matches my father as well as several other known family members on that side of the family on the same segments of DNA.

browser paternal bucket.png

Note that I have a total of 397 matches in common with Buster, 140 of which have been paternally bucketed, 4 of which are both (my children and grandchildren), and 7 of which are maternal.

Those maternal matches represent an issue. It’s possible that those people are either identical by chance or that we share both a maternal and paternal ancestor. All 7 are relatively low matches, with longest blocks from 9 to 14 cM.

Clearly, with a total of 397 shared matches with Buster, not everyone that I match in common with Buster is assigned to a bucket. In fact, 246 are not. I will need to take a look at this group of people and evaluate them individually, their genealogy, clusters, the matrix, and through the chromosome browser to confirm individual matching segments.

There is no single perfect tool.

Every Segment Tells a Unique History

I need to check each of the 14 segments that I match with Buster because each segment has its own inheritance path and may well track back to different ancestors.

browser buster segments.png

It’s also possible that we have unknown common ancestors due to either adoptions, NPEs, or incorrect genealogy, not in the direct Estes patrilineal line, but someplace in our trees.

browser buster paint.png

The best way to investigate the history and genesis of each segment is by painting matching segments at DNAPainter. My matching segments with Buster are shown painted at DNAPainter, above. I wrote about DNAPainter, here.

browser overlap.png

By expanding each segment to show overlapping segments with other matches that I’ve painted and viewing who we match, we can visually see which ancestors that segment descends from and through.

browser dnapainter walk back.png

These roughly 30 individuals all descend from either Lazarus Estes and Elizabeth Vannoy (grey), Elizabeth’s parents (dark blue), or her grandparents (burgundy) on chromosome 15.

As more people match me (and Buster) on this segment, on my father’s side, perhaps we’ll push this segment back further in time to more distant ancestors. Eventually, we may well be able to break through our end-of-line brick wall using these same segments by looking for common upstream ancestors in our matches’ trees.

Arsenal of Tools

This combined arsenal of tools is incredibly exciting, but they all depend on having segment information available and understanding how to use and interpret segment and chromosome browser match information.

One of mine and Buster’s common segments tracks back to end-of-line James Moore, born about 1720, probably in Virginia, and another to Charles Hickerson born about 1724. It’s rewarding and exciting to be able to confirm these DNA segments to specific ancestors. These discoveries may lead to breaking through those brick walls eventually as more people match who share common ancestors with each other that aren’t in my tree.

This is exactly why we need and utilize segment information in a chromosome browser.

We can infer common ancestors from matches, but we can’t confirm segment descent without specific segment information and a chromosome browser. The best we can do, otherwise, is to presume that a preponderance of evidence and numerous matches equates to confirmation. True or not, we can’t push further back in time without knowing who else matches us on those same segments, and the identity of their common ancestors.

The more evidence we can amass for each ancestor and ancestral couple, the better, including:

  • Matches
  • Shared “In Common With” Matches, available at all vendors.
  • Phased Family Matching at Family Tree DNA assigns matches to maternal or paternal sides based on shared, linked DNA from known relatives.
  • The Matrix, a Family Tree DNA tool to determine if matches also match each other. Tester can select who to compare.
  • ThruLines from Ancestry is based on a DNA match and shared ancestors in trees, but no specific segment information or chromosome browser. I wrote about ThruLines here and here.
  • Theories of Family Relativity, aka TOFR, at MyHeritage, based on shared DNA matches, shared ancestors in trees and trees constructed between matches from various genealogical records and sources. MyHeritage includes a chromosome browser and triangulation tool. I wrote about TOFR here and here.
  • Triangulation available through Phased Family Matching at Family Tree DNA and the integrated triangulation tool at MyHeritage. Triangulation between only 3 people at a time is available at 23andMe, although 23andMe does not support trees. See triangulation article links in the Resource Articles section below.
  • AutoClusters at MyHeritage (cluster functionality included), at Genetic Affairs (autoclusters plus tree reconstruction) and at DNAGedcom (including triangulation).
  • Genealogical information. Please upload your trees to every vendor site.
  • Y DNA and mitochondrial DNA confirmation, when available, through Family Tree DNA. I wrote about the 4 Kinds of DNA for Genetic Genealogy, here and the importance of Y DNA confirmation here, and how not having that information can trip you up.
  • Compiled segment information at DNAPainter allows you to combine segment information from various vendors, paint your maternal and paternal chromosomes, and visually walk segments back in time. Article with DNAPainter instructions is found here.

Autosomal Tool Summary Table

In order to help you determine which tool you need to use, and when, I’ve compiled a summary table of the types of tools and when they are most advantageous. Of course, you’ll need to read and understand about each tool in the sections above. This table serves as a reminder checklist to be sure you’ve actually utilized each relevant tool where and how it’s appropriate.

Family Tree DNA MyHeritage Ancestry 23andMe GedMatch
DNA Matches Yes Yes Yes Yes, but only highest 2000 minus whoever does not opt -in Yes, limited matches for free, more with subscription (Tier 1)
Download DNA Segment Match Spreadsheet Yes Yes No, must use DNAGedcom for any download, and no chromosome segment information Yes Tier 1 required, can only download 1000 through visualization options
Segment Spreadsheet Benefits View all matches and sort by segment, target all people who match on specific segments for chromosome browser View all matches and sort by segment, target all people who match on specific segments for chromosome browser No segment information but matches might transfer elsewhere where segment information is available View up to 2000 matches if matches have opted in. If you have initiated contact with a match, they will not drop off match list. Can download highest 1000 matches, target people who match on specific segments
Spreadsheet Challenges Includes small segments, I delete less than 7cM segments before using No X chromosome included No spreadsheet and no segment information Maximum of 2000 matches, minus those not opted in Download limited to 1000 with Tier 1, download not available without subscription
Chromosome Segment Information Yes Yes No, only total and longest segment, no segment address Yes Yes
Chromosome Browser Yes, requires $19 unlock if transfer Yes, requires $29 unlock or subscription if transfer No Yes Yes, some features require Tier 1 subscription
X Chromosome Included Yes No No Yes Yes, separate
Chromosome Browser Benefit Visual view of 7 or fewer matches Visual view of 7 or fewer matches, triangulation included if ALL people match on same portion of common segment No browser Visual view of 5 or fewer matches Unlimited view of matches, multiple options through comparison tools
Chromosome Browser Challenges Can’t tell whether maternal or paternal matches without additional info if don’t select bucketed matches Can’t tell whether maternal or paternal without additional info if don’t triangulate or you don’t know your common ancestor with at least one person in triangulation group No browser Can’t tell whether maternal or paternal without other information Can’t tell whether maternal or paternal without other information
Shared “In Common With” Matches Yes Yes Yes Yes, if everyone opts in Yes
Triangulation Yes, Phased Family Matching, plus chromosome browser Yes, included in chromosome browser if all people being compared match on that segment No, and no browser Yes, but only for 3 people if “Shared DNA” = Yes on Relatives in Common Yes, through multiple comparison tools
Ability to Know if Matches Match Each Other (also see autoclusters) Yes, through Matrix tool or if match on common bucketed segment through Family Matching Yes, through triangulation tool if all match on common segment No Yes, can compare any person to any other person on your match list Yes, through comparison tool selections
Autoclusters Can select up to 10 people for Matrix grid, also available for entire match list through Genetic Affairs and DNAGedcom which work well Genetic Affairs clustering included free, DNAGedcom has difficulty due to timeouts No, but Genetic Affairs and DNAGedcom work well No, but Genetic Affairs and DNAGedcom work well Yes, Genetic Affairs included in Tier 1 for selected kits, DNAGedcom is in beta
Trees Can upload or create tree. Linking you and relatives who match to tree triggers Phased Family Matching Can upload or create tree. Link yourself and kits you manage assists Theories of Family Relativity Can upload or create tree. Link your DNA to your tree to generate ThruLines. Recent new feature allows linking of DNA matches to tree. No tree support but can provide a link to a tree elsewhere Upload your tree so your matches can view
Matching and Automated Tree Construction of DNA Matches who Share Common Ancestors with You Genetic Affairs for matches with common ancestors with you Not available Genetic Affairs for matches with common ancestors with you No tree support Not available
Matching and Automated Tree Construction for DNA Matches with Common Ancestors with Each Other, But Not With You Genetic Affairs for matches with common ancestors with each other, but not with you Not available Genetic Affairs for matches with common ancestors with each other, but not with you No tree support Not available
DNAPainter Segment Compilation and Painting Yes, bucketed Family Match file can be uploaded which benefits tester immensely. Will be able to paint ethnicity segments soon. Yes No segment info available, encourage your matches to upload elsewhere Yes, and can paint ethnicity segments from 23andMe, Yes, but only for individually copied matches or highest 1000.
Y DNA and Mitochondrial Matching Yes, both, includes multiple tools, deep testing and detailed matching No No No, base haplogroup only, no matching No, haplogroup only if field manually completed by tester when uploading autosomal DNA file

Transfer Your DNA

Transferring your DNA results to each vendor who supports segment information and accepts transfers is not only important, it’s also a great way to extend your testing collar. Every vendor has strengths along with people who are found there and in no other database.

Ancestry does not provide segment information nor a chromosome browser, nor accept uploads, but you have several options to transfer your DNA file for free to other vendors who offer tools.

23andMe does provide a chromosome browser but does not accept uploads. You can download your DNA file and transfer free to other vendors.

I wrote detailed upload/download and transfer instructions for each vendor, here.

Two vendors and one third party support transfers into their systems. The transfers include matching. Basic tools are free, but all vendors charge a minimal fee for unlocking advanced tools, which is significantly less expensive than retesting:

Third-party tools that work with your DNA results include:

All vendors provide different tools and have unique strengths. Be sure that your DNA is working as hard as possible for you by fishing in every pond and utilizing third party tools to their highest potential.

Resource Articles

Explanations and step by step explanations of what you will see and what to do, when you open your DNA results for the first time.

Original article about chromosomes having 2 sides and how they affect genetic genealogy.

This article explains what triangulation is for autosomal DNA.

Why some matches may not be valid, and how to tell the difference.

This article explains the difference between a match group, meaning a group of people who match you, and triangulation, where that group also matches each other. The concepts are sound, but this article relies heavily on spreadsheets, before autocluster tools were available.

Parental phasing means assigning segment matches to either your paternal or maternal side.

Updated, introductory article about triangulation, providing the foundation for a series of articles about how to utilize triangulation at each vendor (FamilyTreeDNA, MyHeritage, 23andMe, GEDmatch, DNAPainter) that supports triangulation.

These articles step you through triangulation at each vendor.

DNAPainter facilitates painting maternally and paternally phased, bucketed matches from FamilyTreeDNA, a method of triangulation.

Compiled articles with instructions and ideas for using DNAPainter.

Autoclustering tool instructions.

How and why The Leeds Method works.

Step by step instructions for when and how to use FamilyTreeDNA’s chromosome browser.

Close family members are the key to verifying matches and identifying common ancestors.

This article details how much DNA specific relationships between people can expect to share.

Overview of transfer information and links to instruction articles for each vendor, below.

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Disclosure

I receive a small contribution when you click on some of the links to vendors in my articles. This does NOT increase the price you pay but helps me to keep the lights on and this informational blog free for everyone. Please click on the links in the articles or to the vendors below if you are purchasing products or DNA testing.

Thank you so much.

DNA Purchases and Free Transfers

Genealogy Products and Services

Genealogy Research

Fun DNA Stuff

  • Celebrate DNA – customized DNA themed t-shirts, bags, and other items

Are You DNA Testing the Right People?

We often want to purchase DNA kits for relatives, especially during the holidays when there are so many sales. (There are links for free shipping on tests in addition to sale prices at the end of this article. If you already know who to test, pop on down to the Sales section, now.)

Everyone is on a budget, so who should we test to obtain results that are relevant to our genealogy?

We tell people to test as many family members as possible – but what does that really mean?

Testing everyone may not be financially viable, nor necessary for genealogy, so let’s take a look at how to decide where to spend YOUR testing dollars to derive the most benefit.

It’s All Relative😊

When your ancestors had children, those children inherited different pieces of your ancestors’ DNA.

Therefore, it’s in your best interest to test all of the direct descendants generationally closest to the ancestor that you can find.

It’s especially useful to test descendants of your own close ancestors – great-great-grandparents or closer – where there is a significant possibility that you will match your cousins.

All second cousins match, and roughly 90% (or more) of third cousins match.

Percent of cousins match.png

This nifty chart compiled by ISOGG shows the probability statistics produced by the major testing companies regarding cousin matching relationships.

My policy is to test 4th cousins or closer. The more, the merrier.

Identifying Cousins

  • First cousins share grandparents.
  • Second cousins share great-grandparents.
  • Third cousins share great-great-grandparents.

The easiest way for me to see who these cousins might be is to open my genealogy software on my computer, select my great-great-grandparent, and click on descendants. Pretty much all software has a similar function.

The resulting list shows all of the descendants of that ancestor that I’ve entered in my software. Most genealogists already have or could construct this information with relative ease. These are the cousins you need to be talking to anyway, because they will have photos and stories that you don’t. If you don’t know them, there’s never been a better time to reach out and introduce yourself.

Who to test descendants software

Click to enlarge

People You Already Know

Sometimes it’s easier to start with the family you already know and may see from time to time. Those are the people who will likely be the most beneficial to your genealogy.

Who to test 1C.png

Checking my tree at FamilyTreeDNA, Hiram Ferverda and Evaline MIller are my great-grandparents. All of their children are deceased, but I have a relationship with the children born to their son, Roscoe. Both Cheryl and her brother carry parts of Hiram and Eva’s DNA their son John Ferverda (my grandfather) didn’t inherit, and therefore that I can’t carry.

Therefore, it’s in my best interest to gift my cousin, Cheryl and her brother, both, with DNA kits. Turns out that I already have and my common matches with both Cheryl and her brother are invaluable because I know that people who match me plus either one of them descend from the Ferverda or Miller lines. This relationship and linking them on my tree, shown above, allows Family Tree DNA to perform phased Family Matching which is their form of triangulation.

It’s important to test both siblings, because some people will match me plus one but not the other sibling.

Who’s Relevant?

Trying to convey the concept of who to test and not to test, and why, is sometimes confusing.

Many family members may want to test, but you may only be willing to pay for those tests that can help your own genealogy. We need to know who can best benefit our genealogy in order to make informed decisions.

Let’s look at example scenarios – two focused on grandparents and two on parents.

In our example family, a now-deceased grandmother and grandfather have 3 children and multiple grandchildren. Let’s look at when we test which people, and why.

Example 1: Grandparents – 2 children deceased, 1 living

In our first example, Jane and Barbara, my mother, are deceased, but their sibling Harold is living. Jane has a living daughter and my mother had 3 children, 2 of which are living. Who should we test to discover the most about my maternal grandparents?

Please note that before making this type of a decision, it’s important to state the goal, because the answer will be different depending on your goal at hand. If I wanted to learn about my father’s family, for example, instead of my maternal grandparents, this would be an entirely different question, answer, and tree.

Descendant test

Click to enlarge

The people who are “married in” but irrelevant to the analysis are greyed out. In this case, all of the spouses of Jane, Barbara and Harold are irrelevant to the grandmother and grandfather shown. We are not seeking information about those spouses or their families.

The people I’ve designated with the red stars should be tested. This is the “oldest” generation available. Harold can be tested, so his son, my first cousin, does not need to test because the only part of the grandparent’s DNA that Harold’s son can inherit is a portion of what his father, Harold, carries and gave to him.

Unfortunately, Jane is deceased but her daughter, Liz, is available to test, so Liz’s son does not need to.

I need to test, as does my living brother and the children of my deceased brother in order to recover as much as possible of my mother’s DNA. They will all carry pieces of her DNA that I don’t.

The children of anyone who has a red star do NOT need to test for our stated genealogical purpose because they only carry a portion of thier parent’s DNA, and that parent is already testing.

Those children may want to test for their own genealogy given that they also have a parent who is not relevant to the grandfather and grandmother shown. In my case, I’m perfectly happy to facilitate those tests, but not willing to pay for the children’s tests if the relevant parent is living. I’m only willing to pay for tests that are relevant to my genealogical goals – in this case, my grandparents’ heritage.

In this scenario, I’m providing 5 tests.

Of course, you may have other family factors in play that influence your decision about how many tests to purchase for whom. Family dynamics might include things like hurt feelings and living people who are unwilling or unable to test. I’ve been known to purchase kits for non-biologically related family members so that people could learn how DNA works.

Example 2: Grandparents – 2 children living, one deceased

For our second example, let’s change this scenario slightly.

Descendant test 2

Click to enlarge

From the perspective of only my grandparents’ genealogy, if my mother is alive, there’s no reason to test her children.

Barbara and Harold can test. Since Jane is deceased, and she had only one child, Liz is the closest generationally and can test to represent Jane’s line. Liz’s son does not need to test since his mother, the closest relative generationally to the grandparents is available to test.

In this scenario, I’m providing 3 tests.

Example 3: My Immediate Family – both parents living

In this third example, I’m looking from strictly MY perspective viewing my maternal grandparents (as shown above) AND my immediate family meaning the genealogical lines of both of my parents. In other words, I’ve combined two goals. This makes sense, especially if I’m going to be seeing a group of people at a family gathering. We can have a swab party!

Descendants - parents alive

Click to enlarge

In the situation where my parents are both living, I’m going to test them in addition to Harold and Liz.

I’m testing myself because I want to work using my own DNA, but that’s not really necessary. My parents will both have twice as many matches to other people as I do – because I only inherited half of each parent’s DNA.

In this scenario, I’m providing 5 tests.

Example 4: My Immediate Family – one parent living, one deceased

Descendants - father deceased

Click to enlarge

In our last example, my mother is living but my father is deceased. In addition to Harold and Liz who reflect the DNA of my maternal grandparents, I will test myself, my mother my living brother and my deceased brother’s child.

Because my father is deceased, testing as many of my father’s descendants as possible, in addition to myself, is the only way for me to obtain some portion of his DNA. My siblings will have pieces of my parent’s DNA that I don’t.

I’m not showing my father’s tree in this view, but looking at his tree and who is available to test to provide information about his side of the family would be the next logical step. He may have siblings and cousins that are every bit as valuable as the people on my mother’s side.

Applying this methodology to your own family, who is available to test?

Multiple Databases

Now that you know WHO to test, the next step is to make sure your close family members test at each of the major providers where your DNA is as well.

I test everyone at Family Tree DNA because I have been testing family members there for 19 years and many of the original testers are deceased now. The only way new people can compare to those people is to be in the FamilyTreeDNA data base.

Then, with permission of course, I transfer all kits, for free, to MyHeritage. Matching is free, but if you don’t have a subscription, there’s an unlock fee of $29 to access advanced tools. I have a full subscription, so all tools are entirely free for the kits I transfer and manage in my account.

Transferring to Family Tree DNA and matching there is free too. There’s an unlock fee of $19 for advanced tools, but that’s a good deal because it’s substantially less than a new test.

Neither 23andMe nor Ancestry accept transfers, so you have to test at each of those companies.

The great news is that both Ancestry and 23andMe tests can be transferred to  MyHeritage and FamilyTreeDNA.

Before purchasing tests, check first by asking your relatives or testing there yourself to be sure they aren’t already in those databases. If they took a “spit in a vial” test, they are either at 23andMe or Ancestry. If they took a swab test, it’s MyHeritage or FamilyTreeDNA.

I wrote about creating a testing and transfer strategy in the article, DNA Testing and Transfers – What’s Your Strategy? That article includes a handy dandy chart about who accepts which versions of whose files.

Sales

Of course, everything is on sale since it’s the holidays.

Who are you planning to test?

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I receive a small contribution when you click on some of the links to vendors in my articles. This does NOT increase the price you pay but helps me to keep the lights on and this informational blog free for everyone. Please click on the links in the articles or to the vendors below if you are purchasing products or DNA testing.

Thank you so much.

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Hit a Genetic Genealogy Home Run Using Your Double-Sided Two-Faced Chromosomes While Avoiding Imposters

Do you want to hit a home run with your DNA test, but find yourself a mite bewildered?

Yep, those matches can be somewhat confusing – especially if you don’t understand what’s going on. Do you have a nagging feeling that you might be missing something?

I’m going to explain chromosome matching, and its big sister, triangulation, step by step to remove any confusion, to help you sort through your matches and avoid imposters.

This article is one of the most challenging I’ve ever written – in part because it’s a concept that I’m so familiar with but can be, and is, misinterpreted so easily. I see mistakes and confusion daily, which means that resulting conclusions stand a good chance of being wrong.

I’ve tried to simplify these concepts by giving you easy-to-use memory tools.

There are three key phrases to remember, as memory-joggers when you work through your matches using a chromosome browser: double-sided, two faces and imposter. While these are “cute,” they are also quite useful.

When you’re having a confusing moment, think back to these memory-jogging key words and walk yourself through your matches using these steps.

These three concepts are the foundation of understanding your matches, accurately, as they pertain to your genealogy. Please feel free to share, link or forward this article to your friends and especially your family members (including distant cousins) who work with genetic genealogy. 

Now, it’s time to enjoy your double-sided, two-faced chromosomes and avoid those imposters:)

Are you ready? Grab a nice cup of coffee or tea and learn how to hit home runs!

Double-Sided – Yes, Really

Your chromosomes really are double sided, and two-faced too – and that’s a good thing!

However, it’s initially confusing because when we view our matches in a chromosome browser, it looks like we only have one “bar” or chromosome and our matches from both our maternal and paternal sides are both shown on our one single bar.

How can this be? We all have two copies of chromosome 1, one from each parent.

Chromosome 1 match.png

This is my chromosome 1, with my match showing in blue when compared to my chromosome, in gray, as the background.

However, I don’t know if this blue person matches me on my mother’s or father’s chromosome 1, both of which I inherited. It could be either. Or neither – meaning the dreaded imposter – especially that small blue piece at left.

What you’re seeing above is in essence both “sides” of my chromosome number 1, blended together, in one bar. That’s what I mean by double-sided.

There’s no way to tell which side or match is maternal and which is paternal without additional information – and misunderstanding leads to misinterpreting results.

Let’s straighten this out and talk about what matches do and don’t mean – and why they can be perplexing. Oh, and how to discover those imposters!

Your Three Matches

Let’s say you have three matches.

At Family Tree DNA, the example chromosome browser I’m using, or at any vendor with a chromosome browser, you select your matches which are viewed against your chromosomes. Your chromosomes are always the background, meaning in this case, the grey background.

Chromosome 1-4.png

  • This is NOT three copies each of your chromosomes 1, 2, 3 and 4.
  • This is NOT displaying your maternal and paternal copies of each chromosome pictured.
  • We CANNOT tell anything from this image alone relative to maternal and paternal side matches.
  • This IS showing three individual people matching you on your chromosome 1 and the same three people matching you in the same order on every chromosome in the picture.

Let’s look at what this means and why we want to utilize a chromosome browser.

I selected three matches that I know are not all related through the same parent so I can demonstrate how confusing matches can be sorted out. Throughout this article, I’ve tried to explain each concept in at least two ways.

Please note that I’m using only chromsomes 1-4 as examples, not because they are any more, or less, important than the other chromosomes, but because showing all 22 would not add any benefit to the discussion. The X chromosome has a separate inheritance path and I wrote about that here.

Let’s start with a basic question.

Why Would I Want to Use a Chromosome Browser?

Genealogists view matches on chromosome browsers because:

  • We want to see where our matches match us on our chromosomes
  • We’d like to identify our common ancestor with our match
  • We want to assign a matching segment to a specific ancestor or ancestral line, which confirmed those ancestors as ours
  • When multiple people match us on the same location on the chromosome browser, that’s a hint telling us that we need to scrutinize those matches more closely to determine if those people match us on our maternal or paternal side which is the first step in assigning that segment to an ancestor

Once we accurately assign a segment to an ancestor, when anyone else matches us (and those other people) on that same segment, we know which ancestral line they match through – which is a great head start in terms of identifying our common ancestor with our new match.

That’s a genetic genealogy home run!

Home Runs 

There are four bases in a genetic genealogy home run.

  1. Determine whether you actually match someone on the same segment
  2. Which is the first step in determining that you match a group of people on the same segment
  3. And that you descend from a common ancestor
  4. The fourth step, or the home run, is to determine which ancestor you have in common, assigning that segment to that ancestor

If you can’t see segment information, you can’t use a chromosome browser and you can’t confirm the match on that segment, nor can you assign that segment to a particular ancestor, or ancestral couple.

The entire purpose of genealogy is to identify and confirm ancestors. Genetic genealogy confirms the paper trail and breaks down even more brick walls.

But before you can do that, you have to understand what matches mean and how to use them.

The first step is to understand that our chromosomes are double-sided and you can’ t see both of your chromosomes at once!

Double Sided – You Can’t See Both of Your Chromosomes at Once

The confusing part of the chromosome browser is that it can only “see” your two chromosomes blended as one. They are both there, but you just can’t see them separately.

Here’s the important concept:

You have 2 copies of chromosomes 1 through 22 – one copy that you received from your mother and one from your father, but you can’t “see” them separately.

When your DNA is sequenced, your DNA from your parents’ chromosomes emerges as if it has been through a blender. Your mother’s chromosome 1 and your father’s chromosome 1 are blended together. That means that without additional information, the vendor can’t tell which matches are from your father’s side and which are from your mother’s side – and neither can you.

All the vendor can tell is that someone matches you on the blended version of your parents. This isn’t a negative reflection on the vendors, it’s just how the science works.

Chromosome 1.png

Applying this to chromosome 1, above, means that each segment from each person, the blue person, the red person and the teal person might match you on either one of your chromosomes – the paternal chromosome or the maternal chromosome – but because the DNA of your mother and father are blended – there’s no way without additional information to sort your chromosome 1 into a maternal and paternal “side.”

Hence, you’re viewing “one” copy of your combined chromosomes above, but it’s actually “two-sided” with both maternal and paternal matches displayed in the chromosome browser.

Parent-Child Matches

Let’s explain this another way.

Chromosome parent.png

The example above shows one of my parents matching me. Don’t be deceived by the color blue which is selected randomly. It could be either parent. We don’t know.

You can see that I match my parent on the entire length of chromosome 1, but there is no way for me to tell if I’m looking at my mother’s match or my father’s match, because both of my parents (and my children) will match me on exactly the same locations (all of them) on my chromosome 1.

Chromosome parent child.png

In fact, here is a combination of my children and my parents matching me on my chromosome 1.

To sort out who is matching on paternal and maternal chromosomes, or the double sides, I need more information. Let’s look at how inheritance works.

Stay with me!

Inheritance Example

Let’s take a look at how inheritance works visually, using an example segment on chromosome 1.

Chromosome inheritance.png

In the example above:

  • The first column shows addresses 1-10 on chromosome 1. In this illustration, we are only looking at positions, chromosome locations or addresses 1-10, but real chromosomes have tens of thousands of addresses. Think of your chromosome as a street with the same house numbers on both sides. One side is Mom’s and one side is Dad’s, but you can’t tell which is which by looking at the house numbers because the house numbers are identical on both sides of the street.
  • The DNA pieces, or nucleotides (T, A, C or G,) that you received from your Mom are shown in the column labeled Mom #1, meaning we’re looking at your mother’s pink chromosome #1 at addresses 1-10. In our example she has all As that live on her side of the street at addresses 1-10.
  • The DNA pieces that you received from your Dad are shown in the blue column and are all Cs living on his side of the street in locations 1-10.

In other words, the values that live in the Mom and Dad locations on your chromosome streets are different. Two different faces.

However, all that the laboratory equipment can see is that there are two values at address 1, A and C, in no particular order. The lab can’t tell which nucleotide came from which parent or which side of the street they live on.

The DNA sequencer knows that it found two values at each address, meaning that there are two DNA strands, but the output is jumbled, as shown in the First and Second read columns. The machine knows that you have an A and C at the first address, and a C and A at the second address, but it can’t put the sequence of all As together and the sequence of all Cs together. What the sequencer sees is entirely unordered.

This happens because your maternal and paternal DNA is mixed together during the extraction process.

Chromosome actual

Click to enlarge image.

Looking at the portion of chromosome 1 where the blue and teal people both match you – your actual blended values are shown overlayed on that segment, above. We don’t know why the blue and the teal people are matching you. They could be matching because they have all As (maternal), all Cs (paternal) or some combination of As and Cs (a false positive match that is identical by chance.)

There are only two ways to reassemble your nucleotides (T, A, C, and G) in order and then to identify the sides as maternal and paternal – phasing and matching.

As you read this next section, it does NOT mean that you must have a parent for a chromosome browser to be useful – but it does mean you need to understand these concepts.

There are two types of phasing.

Parental Phasing

  • Parental Phasing is when your DNA is compared against that of one or both parents and sorted based on that comparison.

Chromosome inheritance actual.png

Parental phasing requires that at least one parent’s DNA is available, has been sequenced and is available for matching.

In our example, Dad’s first 10 locations (that you inherited) on chromosome 1 are shown, at left, with your two values shown as the first and second reads. One of your read values came from your father and the other one came from your mother. In this case, the Cs came from your father. (I’m using A and C as examples, but the values could just as easily be T or G or any combination.)

When parental phasing occurs, the DNA of one of your parents is compared to yours. In this case, your Dad gave you a C in locations 1-10.

Now, the vendor can look at your DNA and assign your DNA to one parent or the other. There can be some complicating factors, like if both your parents have the same nucleotides, but let’s keep our example simple.

In our example above, you can see that I’ve colored portions of the first and second strands blue to represent that the C value at that address can be assigned through parental phasing to your father.

Conversely, because your mother’s DNA is NOT available in our example, we can’t compare your DNA to hers, but all is not lost. Because we know which nucleotides came from your father, the remaining nucleotides had to come from your mother. Hence, the As remain after the Cs are assigned to your father and belong to your mother. These remaining nucleotides can logically be recombined into your mother’s DNA – because we’ve subtracted Dad’s DNA.

I’ve reassembled Mom, in pink, at right.

Statistical/Academic Phasing

  • A second type of phasing uses something referred to as statistical or academic phasing.

Statistical phasing is less successful because it uses statistical calculations based on reference populations. In other words, it uses a “most likely” scenario.

By studying reference populations, we know scientifically that, generally, for our example addresses 1-10, we either see all As or all Cs grouped together.

Based on this knowledge, the Cs can then logically be grouped together on one “side” and As grouped together on the other “side,” but we still have no way to know which side is maternal or paternal for you. We only know that normally, in a specific population, we see all As or all Cs. After assigning strings or groups of nucleotides together, the algorithm then attempts to see which groups are found together, thereby assigning genetic “sides.” Assigning the wrong groups to the wrong side sometimes happens using statistical phasing and is called strand swap.

Once the DNA is assigned to physical “sides” without a parent or matching, we still can’t identify which side is paternal and which is maternal for you.

Statistical or academic phasing isn’t always accurate, in part because of the differences found in various reference populations and resulting admixture. Sometimes segments don’t match well with any population. As more people test and more reference populations become available, statistical/academic phasing improves. 23andMe uses academic phasing for ethnicity, resulting in a strand swap error for me. Ancestry uses academic phasing before matching.

By comparison to statistical or academic phasing, parental phasing with either or both parents is highly accurate which is why we test our parents and grandparents whenever possible. Even if the vendor doesn’t use our parents’ results, we certainly can!

If someone matches you and your parent too, you know that match is from that parent’s side of your tree.

Matching

The second methodology to sort your DNA into maternal and paternal sides is matching, either with or without your parents.

Matching to multiple known relatives on specific segments assigns those segments of your DNA to the common ancestor of those individuals.

In other words, when I match my first cousin, and our genealogy indicates that we share grandparents – assuming we match on the appropriate amount of DNA for the expected relationship – that match goes a long way to confirming our common ancestor(s).

The closer the relationship, the more comfortable we can be with the confirmation. For example, if you match someone at a parental level, they must be either your biological mother, father or child.

While parent, sibling and close relationships are relatively obvious, more distant relationships are not and can occur though unknown or multiple ancestors. In those cases, we need multiple matches through different children of that ancestor to reasonably confirm ancestral descent.

Ok, but how do we do that? Let’s start with some basics that can be confusing.

What are we really seeing when we look at a chromosome browser?

The Grey/Opaque Background is Your Chromosome

It’s important to realize that you will see as many images of your chromosome(s) as people you have selected to match against.

This means that if you’ve selected 3 people to match against your chromosomes, then you’ll see three images of your chromosome 1, three images of your chromosome 2, three images of your chromosome 3, three images of your chromosome 4, and so forth.

Remember, chromosomes are double-sided, so you don’t know whether these are maternal or paternal matches (or imposters.)

In the illustration below, I’ve selected three people to match against my chromosomes in the chromosome browser. One person is shown as a blue match, one as a red match, and one as a teal match. Where these three people match me on each chromosome is shown by the colored segments on the three separate images.

Chromosome 1.png

My chromosome 1 is shown above. These images are simply three people matching to my chromosome 1, stacked on top of each other, like cordwood.

The first image is for the blue person. The second image is for the red person. The third image is for the teal person.

If I selected another person, they would be assigned a different color (by the system) and a fourth stacked image would occur.

These stacked images of your chromosomes are NOT inherently maternal or paternal.

In other words, the blue person could match me maternally and the red person paternally, or any combination of maternal and paternal. Colors are not relevant – in other words colors are system assigned randomly.

Notice that portions of the blue and teal matches overlap at some of the same locations/addresses, which is immediately visible when using a chromosome browser. These areas of common matching are of particular interest.

Let’s look closer at how chromosome browser matching works.

What about those colorful bars?

Chromosome Browser Matching

When you look at your chromosome browser matches, you may see colored bars on several chromosomes. In the display for each chromosome, the same color will always be shown in the same order. Most people, unless very close relatives, won’t match you on every chromosome.

Below, we’re looking at three individuals matching on my chromosomes 1, 2, 3 and 4.

Chromosome browser.png

The blue person will be shown in location A on every chromosome at the top. You can see that the blue person does not match me on chromosome 2 but does match me on chromosomes 1, 3 and 4.

The red person will always be shown in the second position, B, on each chromosome. The red person does not match me on chromosomes 2 or 4.

The aqua person will always be shown in position C on each chromosome. The aqua person matches me on at least a small segment of chromosomes 1-4.

When you close the browser and select different people to match, the colors will change and the stacking order perhaps, but each person selected will always be consistently displayed in the same position on all of your chromosomes each time you view.

The Same Address – Stacked Matches

In the example above, we can see that several locations show stacked segments in the same location on the browser.

Chromosome browser locations.png

This means that on chromosome 1, the blue and green person both match me on at least part of the same addresses – the areas that overlap fully. Remember, we don’t know if that means the maternal side or the paternal side of the street. Each match could match on the same or different sides.

Said another way, blue could be maternal and teal could be paternal (or vice versa,) or both could be maternal or paternal. One or the other or both could be imposters, although with large segments that’s very unlikely.

On chromosome 4, blue and teal both match me on two common locations, but the teal person extends beyond the length of the matching blue segments.

Chromosome 3 is different because all three people match me at the same address. Even though the red and teal matching segments are longer, the shared portion of the segment between all three people, the length of the blue segment, is significant.

The fact that the stacked matches are in the same places on the chromosomes, directly above/below each other, DOES NOT mean the matches also match each other.

The only way to know whether these matches are both on one side of my tree is whether or not they match each other. Do they look the same or different? One face or two? We can’t tell from this view alone.

We need to evaluate!

Two Faces – Matching Can be Deceptive!

What do these matches mean? Let’s ask and answer a few questions.

  • Does a stacked match mean that one of these people match on my mother’s side and one on my father’s side?

They might, but stacked matches don’t MEAN that.

If one match is maternal, and one is paternal, they still appear at the same location on your chromosome browser because Mom and Dad each have a side of the street, meaning a chromosome that you inherited.

Remember in our example that even though they have the same street address, Dad has blue Cs and Mom has pink As living at that location. In other words, their faces look different. So unless Mom and Dad have the same DNA on that entire segment of addresses, 1-10, Mom and Dad won’t match each other.

Therefore, my maternal and paternal matches won’t match each other either on that segment either, unless:

  1. They are related to me through both of my parents and on that specific location.
  2. My mother and father are related to each other and their DNA is the same on that segment.
  3. There is significant endogamy that causes my parents to share DNA segments from their more distant ancestors, even though they are not related in the past few generations.
  4. The segments are small (segments less than 7cM are false matches roughly 50% of the time) and therefore the match is simply identical by chance. I wrote about that here. The chart showing valid cM match percentages is shown here, but to summarize, 7-8 cMs are valid roughly 46% of the time, 8-9 cM roughly 66%, 9-10 cM roughly 91%, 10-11 cM roughly 95, but 100 is not reached until about 20 cM and I have seen a few exceptions above that, especially when imputation is involved.

Chromosome inheritance match.png

In this inheritance example, we see that pink Match #1 is from Mom’s side and matches the DNA I inherited from pink Mom. Blue Match #2 is from Dad’s side and matches the DNA I inherited from blue Dad. But as you can see, Match #1 and Match #2 do not match each other.

Therefore, the address is only half the story (double-sided.)

What lives at the address is the other half. Mom and Dad have two separate faces!

Chromosome actual overlay

Click to enlarge image

Looking at our example of what our DNA in parental order really looks like on chromosome 1, we see that the blue person actually matches on my maternal side with all As, and the teal person on the paternal side with all Cs.

  • Does a stacked match on the chromosome browser mean that two people match each other?

Sometimes it happens, but not necessarily, as shown in our example above. The blue and teal person would not match each other. Remember, addresses (the street is double-sided) but the nucleotides that live at that address tell the real story. Think two different looking faces, Mom’s and Dad’s, peering out those windows.

If stacked matches match each other too – then they match me on the same parental side. If they don’t match each other, don’t be deceived just because they live at the same address. Remember – Mom’s and Dad’s two faces look different.

For example, if both the blue and teal person match me maternally, with all As, they would also match each other. The addresses match and the values that live at the address match too. They look exactly the same – so they both match me on either my maternal or paternal side – but it’s up to me to figure out which is which using genealogy.

Chromosome actual maternal.png

Click to enlarge image

When my matches do match each other on this segment, plus match me of course, it’s called triangulation.

Triangulation – Think of 3

If my two matches match each other on this segment, in addition to me, it’s called triangulation which is genealogically significant, assuming:

  1. That the triangulated people are not closely related. Triangulation with two siblings, for example, isn’t terribly significant because the common ancestor is only their parents. Same situation with a child and a parent.
  2. The triangulated segments are not small. Triangulation, like matching, on small segments can happen by chance.
  3. Enough people triangulate on the same segment that descends from a common ancestor to confirm the validity of the common ancestor’s identity, also confirming that the match is identical by descent, not identical by chance.

Chromosome inheritance triangulation.png

The key to determining whether my two matches both match me on my maternal side (above) or paternal side is whether they also match each other.

If so, assuming all three of the conditions above are true, we triangulate.

Next, let’s look at a three-person match on the same segment and how to determine if they triangulate.

Three Way Matching and Identifying Imposters

Chromosome 3 in our example is slightly different, because all three people match me on at least a portion of that segment, meaning at the same address. The red and teal segments line up directly under the blue segment – so the portion that I can potentially match identically to all 3 people is the length of the blue segment. It’s easy to get excited, but don’t get excited quite yet.

Chromosome 3 way match.png

Given that three people match me on the same street address/location, one of the following three situations must be true:

  • Situation 1- All three people match each other in addition to me, on that same segment, which means that all three of them match me on either the maternal or paternal side. This confirms that we are related on the same side, but not how or which side.

Chromosome paternal.png

In order to determine which side, maternal or paternal, I need to look at their and my genealogy. The blue arrows in these examples mean that I’ve determined these matches to all be on my father’s side utilizing a combination of genealogy plus DNA matching. If your parent is alive, this part is easy. If not, you’ll need to utilize common matching and/or triangulation with known relatives.

  • Situation 2 – Of these three people, Cheryl, the blue bar on top, matches me but does not match the other two. Charlene and David, the red and teal, match each other, plus me, but not Cheryl.

Chromosome maternal paternal.png

This means that at least either my maternal or paternal side is represented, given that Charlene and David also match each other. Until I can look at the identity of who matches, or their genealogy, I can’t tell which person or people descend from which side.

In this case, I’ve determined that Cheryl, my first cousin, with the pink arrow matches me on Mom’s side and Charlene and David, with the blue arrows, match me on Dad’s side. So both my maternal and paternal sides are represented – my maternal side with the pink arrow as well as my father’s side with the blue arrows.

If Cheryl was a more distant match, I would need additional triangulated matches to family members to confirm her match as legitimate and not a false positive or identical by chance.

  • Situation 3 – Of the three people, all three match me at the same addresses, but none of the three people match each other. How is this even possible?

Chromosome identical by chance.png

This situation seems very counter-intuitive since I have only 2 chromosomes, one from Mom and one from Dad – 2 sidesof the street. It is confusing until you realize that one match (Cheryl and me, pink arrow) would be maternal, one would be paternal (Charlene and me, blue arrow) and the third (David and me, red arrows) would have DNA that bounces back and forth between my maternal and paternal sides, meaning the match with David is identical by chance (IBC.)

This means the third person, David, would match me, but not the people that are actually maternal and paternal matches. Let’s take a look at how this works

Chromosome maternal paternal IBC.png

The addresses are the same, but the values that live at the addresses are not in this third scenario.

Maternal pink Match #1 is Cheryl, paternal blue Match #2 is Charlene.

In this example, Match #3, David, matches me because he has pink and blue at the same addresses that Mom and Dad have pink and blue, but he doesn’t have all pink (Mom) nor all blue (Dad), so he does NOT match either Cheryl or Charlene. This means that he is not a valid genealogical match – but is instead what is known as a false positive – identical by chance, not by descent. In essence, a wily genetic imposter waiting to fool unwary genealogists!

In his case, David is literally “two-faced” with parts of both values that live in the maternal house and the paternal house at those addresses. He is a “two-faced imposter” because he has elements of both but isn’t either maternal or paternal.

This is the perfect example of why matching and triangulating to known and confirmed family members is critical.

All three people, Cheryl, Charlene and David match me (double sided chromosomes), but none of them match each other (two legitimate faces – one from each parent’s side plus one imposter that doesn’t match either the legitimate maternal or paternal relatives on that segment.)

Remember Three Things

  1. Double-Sided – Mom and Dad both have the same addresses on both sides of each chromosome street.
  2. Two Legitimate Faces – The DNA values, nucleotides, will have a unique pattern for both your Mom and Dad (unless they are endogamous or related) and therefore, there are two legitimate matching patterns on each chromsome – one for Mom and one for Dad. Two legitimate and different faces peering out of the houses on Mom’s side and Dad’s side of the street.
  3. Two-Faced Imposters – those identical by chance matches which zig-zag back and forth between Mom and Dad’s DNA at any given address (segment), don’t match confirmed maternal and paternal relatives on the same segment, and are confusing imposters.

Are you ready to hit your home run?

What’s Next?

Now that we understand how matching and triangulation works and why, let’s put this to work at the vendors. Join me for my article in a few days, Triangulation in Action at Family Tree DNA, MyHeritage, 23andMe and GedMatch.

We will step through how triangulation works at each vendor. You’ll have matches at each vendor that you don’ t have elsewhere. If you haven’t transferred your DNA file yet, you still have time with the step by step instructions below:

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Disclosure

I receive a small contribution when you click on some of the links to vendors in my articles. This does NOT increase the price you pay but helps me to keep the lights on and this informational blog free for everyone. Please click on the links in the articles or to the vendors below if you are purchasing products or DNA testing.

Thank you so much.

DNA Purchases and Free Transfers

Genealogy Services

Genealogy Research

Mitochondrial DNA Resources – Everything You Need to Know

Mitochondrial DNA Resources

Recently, I wrote a multi-part series about mitochondrial DNA – start to finish – everything you need to know.

I’ve assembled several articles in one place, and I’ll add any new articles here as well.

Please feel free to share this resource or any of the links to individual articles with friends, genealogy groups or on social media.

What the Difference Between Mitochondrial and Other Types of DNA?

Mitochondrial DNA is inherited directly from your matrilineal line, only, meaning your mother’s mother’s mother’s mother – on up your family tree until you run out of direct line mothers that you’ve identified. The great news is even if you don’t know the identities of those people in your tree, you carry their mitochondrial DNA which can help identify them.

Here’s a short article about the different kinds of DNA that can be used for genealogy.

Why Mitochondrial DNA?

Let’s start out with why someone might want to test their mitochondrial DNA.

After you purchase a DNA test, swab, return the kit and when the lab finishes processing your test, you’ll receive your results on your personal page at FamilyTreeDNA, the only company that tests mitochondrial DNA at the full sequence level and provides matching with tens of thousands of other testers.

What About Those Results?

People want to understand how to use all of the different information provided to testers. These articles provide a step-by-step primer.

Mitochondrial DNA personal page update

Sign in to your Family Tree DNA account and use these articles as a guideline to step through your results on your personal page.

We begin with an overview. What is mitochondrial DNA, how it is inherited and why is it useful for genealogy?

Next, we look at your results and decode what all the numbers mean. It’s easy, really!

Our ancestors lived in clans, and our mitochondrial DNA has its own versions of clans too – called haplogroups. Your full haplogroup can be very informative.

Sometimes there’s more than meets the eye. Here are my own tips and techniques for more than doubling the usefulness of your matches.

You’ll want to wring every possible advantage out of your tests, so be sure to join relevant projects and use them to their fullest extent.

Do you know how to utilize advanced matching? It’s a very powerful tool. If not, you will after these articles.

Mitochondrial DNA Information for Everyone

FamilyTreeDNA maintains an extensive public mitochondrial DNA tree, complete with countries of origin for all branches. You don’t need to have tested to enjoy the public tree.

However, if you have tested, take a look to see where the earliest known ancestors of your haplogroup matches are located based on the country flags.

Mitochondrial resources haplotree

These are mine. Where are yours?

What Can Mitochondrial DNA Do for You?

Some people mistakenly think that mitochondrial DNA isn’t useful for genealogy. I’m here to testify that it’s not only useful, it’s amazing! Here are three stories from my own genealogy about how I’ve used mitochondrial DNA to learn more about my ancestors and in some cases, break right through brick walls.

It’s not only your own mitochondrial DNA that’s important, but other family members too.

My cousin tested her mitochondrial DNA to discover that her direct matrilineal ancestor was Native American, much to her surprise. The great news is that her ancestor is my ancestor too!

Searching for Native American Ancestors?

If you’re searching for Native American or particular ancestors, mitochondrial DNA can tell you specifically if your mitochondrial DNA, or that of your ancestors (if you test a direct matrilineal descendant,) is Native, African, European, Jewish or Asian. Furthermore, your matches provide clues as to what country your ancestor might be from and sometimes which regions too.

Did you know that people from different parts of the world have distinctive haplogroups?

You can discover your ancestors’ origins through their mitochondrial DNA.

You can even utilize autosomal segment information to track back in time to the ancestor you seek. Then you can obtain that ancestor’s mitochondrial DNA by selectively testing their descendants or finding people who have already tested that descend from that ancestor. Here’s how.

You never know what you’re going to discover when you test your mitochondrial DNA. I discovered that although my earliest known matrilineal ancestor is found in Germany, her ancestors were from Scandinavia. My cousin discovered that our common ancestor is Mi’kmaq.

What secrets will your mitochondrial DNA reveal?

You can test or upgrade your mitochondrial DNA by clicking here.

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Disclosure

I receive a small contribution when you click on some of the links to vendors in my articles. This does NOT increase the price you pay but helps me to keep the lights on and this informational blog free for everyone. Please click on the links in the articles or to the vendors below if you are purchasing products or DNA testing.

Thank you so much.

DNA Purchases and Free Transfers

Genealogy Services

Genealogy Research

Concepts: What are NPEs and MPEs?

Child with helix

Sooner or later in genetic genealogy, you’re going to run across the acronym, NPE or MPE.

Years ago, the phrase NPE was coined to generally mean when the expected parent or parents weren’t.

  • NPE means nonpaternal event, also sometimes nonparental event.
  • Some folks didn’t like that term and began to use MPE, misattributed paternal event or misattributed parentage.

Of course, today, this situation could arise as a result of an adoption, a donor situation, either male or female, or the more often thought-of situation where the father isn’t who he’s presumed/believed to be based on the circumstances at hand.

Historically, adoptions weren’t a legal situation. If the parents died on the wagon train, someone took the kids to raise. Ditto a woman raising her sister’s children.

At that time, everyone knew the situation and it wasn’t a secret. A couple (or more) generations later, no one knows and the presumed parent(s) aren’t, especially if the child used the surname of the people who raised him or her. That’s a very common step-father situation, especially before official birth certificates.

Regardless of the situation, the “adoption” was undocumented for future generations. Hence, the term “undocumented adoption.” I’ve used “undocumented adoption” for a long time because I felt there was less judgement inherent in that description. Other people simply say “of unknown parentage.”

Discoveries are Common

Of course today with various types of DNA testing, these types of situations are slowly, or not so slowly, being discovered.

When they reveal themselves, you may have to saw a branch off of your tree. That’s ugly if you’re a genealogist, but at least it’s not someone you know personally.

However, if the people involved are closer in time, the discovery may be a shock or traumatic. I experienced this with my half-brother, Dave, who turned out not to be my biological brother.  I found him and then heartbreakingly lost him. I loved him regardless and wrote about our journey here, here and here.

These situations used to be remarkable, but with so many people DNA testing, these revelations are becoming daily events.

No Judgement

While the first thought that might occur is that someone was cheating, that may not be the case at all. Lots of circumstances may come into play. I wrote about several here.

I would encourage everyone to suspend judgement, not assume and to give our ancestors and family members the benefit of the doubt. We don’t and can’t know what happened to them.

Moccasins and glass houses😊

Besides that – if it wasn’t for your ancestors, you wouldn’t be you!

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Disclosure

I receive a small contribution when you click on the link to one of the vendors in my articles. This does NOT increase the price you pay but helps me to keep the lights on and this informational blog free for everyone. Please click on the links in the articles or to the vendors below if you are purchasing products or DNA testing.

Thank you so much.

DNA Purchases and Free Transfers

Genealogy Services

Genealogy Research

Identifying Unknown Parents and Individuals Using DNA Matching

There have been a lot of questions recently about the methodology used by people searching for unknown parents and other unidentified individuals. I covered this technique in concept recently at a conference as part of an overview presentation. In this article, I’m addressing only this topic and in more detail.

What is the methodology that genealogists use to identify unknown parents? It’s exactly the same process used to identify unknown Does, meaning unidentified bodies as well as violent criminals who have left DNA, such as blood or semen, at a crime scene.

How is Identifying Unknown Individuals Different from Genealogy?

Genealogists are interested in discovering their ancestors. Generally, genealogists know who their parents are and most of the time, their grandparents as well. Not very many people can tell you the names of their great-grandparents off the top of their head – not unless they ARE genealogists😊

Genealogists interview family members and access family sources, such as photos, Bibles, boxes of memorabilia and often extend their family another generation or two using these resources. Then, to gather additional information, genealogists turn to publicly available sources such as:

Constructing a Tree

Genealogists utilize software to create trees of their ancestors, either on their own computers with software such as Family Tree Maker, Legacy, RootsMagic or the free tree building software from MyHeritage. They then either synchronize or duplicate their tree on the public sites mentioned above which provide functionality such as “hints” that point to documents relevant to the ancestors in their tree. Additionally, they can access the trees of other genealogists who are researching the same ancestors. This facilitates the continued growth of their tree by adding ancestors and extending the tree back generations.

While tree-building is the goal of genealogists, the trees they build are important tools for people seeking to identify unknown individuals.

The Tree

Generations tree

In my tree, shown in the format of a pedigree chart, above, you can see that I’ve identified all 16 of my great-great-grandparents. In reality, because I’ve been a genealogist for decades, I’ve identified many more of my ancestors which are reflected in my tree on my computer and in my trees at both Ancestry and MyHeritage where I benefit from hints and DNA matches.

Genealogical pedigree charts are typically represented with the “home person,” me, in this case at the base with my ancestors branching out behind them like a lovely peacock’s tail.

While I’m looking for distant ancestors, adoptees and others seeking the identities of contemporary people are not looking back generations, but seek to identify contemporary generations, meaning people who are alive or lived very recently, typically within a generation.

Enter the world of genetics and DNA matching.

Genetics, The Game Changing Tool

Before the days of DNA testing, adoptees could only hope that someone knew the identify of their biological parents, or that their biological parents registered with a reunion site, or that their court records could be opened.

DNA testing changed all of that, because people can now DNA test and find their close relatives. As more people test, the better the odds of actually having a parent or sibling match, or perhaps a close relative like an aunt, uncle or first cousin. My closest relative that has tested that I didn’t know was testing is my half-sister’s daughter.

You share grandparents with your first cousin, and since you only have 4 grandparents, it’s not terribly difficult to figure out which set of grandparents you connect to through that first cousin – especially given the size of the databases and the number of matches that people have today.

The chart below shows my matches as of June 2019.

Vendor

Total Matches

Second Cousin or Closer

Family Tree DNA

4,609

18

MyHeritage

9,644

14

23andMe

1,501

5

Ancestry

80,151

8

You can see that I have a total of 45 close matches, although some of those matches are duplicates of each other. However, each database has some people that are only in that database and have not tested at other companies or transferred to other databases.

Situations like this are exactly why people who are searching for unknown family members take DNA tests at all 4 of the vendors.

Stories were once surprising about people who tested and either discover a previously unknown close relative, or conversely discovered that they are not related to someone who they initially believed they were. Today these occurrences are commonplace.

Matches

If you’re searching for an unknown parent or close relative, you just might be lucky to receive a parental, sibling, half-sibling or uncle/aunt match immediately.

An estimated relationship range is provided by all vendors based on the amount of DNA that the tester shares with their match.

Generations Family Tree DNA matches

My mother’s match page at Family Tree DNA is shown above. You can see that I’m Mother’s closest match. My known half brother did not test before he passed away, and mother’s parents are long deceased, so my mother should NEVER have another match this close.

So, who is that person in row 2 that is also predicted to be a mother or daughter? I took a test at Ancestry and uploaded my results to Family Tree DNA for research purposes, so this is actually my own second kit, but for example purposes, I’ve renamed myself “Example Adoptee.” Judging from the photo here, apparently my “adopted” sibling was a twin😊

If the adoptee tested at Family Tree DNA, she would immediately see a sibling match (me) and a parent match (Mom.) A match at that cM (centiMorgan) level can only be a parent or a child, and the adoptee knows whether she has a child or not.

Let’s look at a more distant example, which is probably more “typical” than immediately finding a parent match.

Let’s say that the “male adoptee” at the bottom in the red box is also searching for his birth family. He matches my mother at the 2nd-3rd cousin level, so someplace in her tree are his ancestors too.

People who have trees are shown with gold boxes around the tiny pedigree icons, because they literally are trees of gold.

Because of Family Tree DNA’s “bucketing” tool, the software has already told my Mother that the male adoptee is a match on her father’s side of her tree. The adoptee can click on the little pedigree icon to view the trees of his matches to view their ancestors, then engage in what is known as “tree triangulation” with his other close matches.

From the Perspective of the Adoptee

An adoptee tests not knowing anything about their ancestors.

Generations adoptee

When their results come back, the adoptee, in the red box in the center, hoping to identify their biological parents, discovers that their closest matches are the testers in the pink and blue ovals.

The adoptee does NOT know that these people are related to each other at this point, only that these 7 people are their closest matches on their match list.

The adoptee has to put the rest of the story together like a puzzle.

Who Matches Each Other?

In our scenario, test takers 2, 3 and 8 don’t match the adoptee, so the adoptee will never know they tested and vice versa. Everyone at a second cousin level will match each other, but only some people will match at more distant relationships, according to statistics published by 23andMe:

Relationship Level

Percentage of People Who Match

Parents, siblings, aunts, uncles, half siblings, half aunts/uncles and 1st cousins

100%

2nd cousins

>99%

3rd cousins

90%

4th cousins

45%

5th cousins

15%

6th cousins and more distant

<5%

You can view a detailed chart with additional relationships here.

Tree Triangulation

By looking at the individual trees of test taker 1, 4 and 5 whom they match, the adoptee notices that John and Jane Doe are common ancestors in the trees of all 3 test takers. The adoptee may also use “in common with” tools provided by each vendor to see who they match “in common with” another tester. In this case, let’s say that test taker 1, 4 and 5 also match each other, so the adoptee would also make note of that, inferring correctly that they are members of the same family.

The goal is to identify a common ancestor of a group of matches in order to construct the ancestor’s tree, not a pedigree chart backwards in time, as with genealogy, but to construct a descendants’ tree from the ancestral couple to the current day, as completely as possible. After all, the goal is to identify the parent of the adoptee who descends from the common ancestor.

Generations adoptee theory

In this case, the adoptee realized that the pink test takers descended from John and Jane Doe, and the blue test takers descended from Walter and Winnie Smith, and constructed descendant trees of both couples.

The adoptee created a theory, based on the descendants of these two ancestral couples, incorporating other known facts, such as the year when the adoptee was born, and where.

In our example, the adoptee discovered that John and Jane Doe had another daughter, Juanita, whose descendants don’t appear to have tested, and that Juanita had a daughter who was in the right place at the right time to potentially be the mother of the adoptee.

Conversely, Walter and Winnie Smith had a son whose descendants also appear to have not tested, and he had a son who lived in the same place as Juanita Doe. In other words, age, opportunity and process of elimination all play a role in addition to DNA matches. DNA is only the first hint that must be followed up by additional research.

At this point, if the adoptee has taken either Y or mitochondrial DNA testing, those results can serve to either include or exclude some candidates at Family Tree DNA. For example, if the adoptee was a male and matched the Y DNA of the Smith line, that would be HUGE hint.

From this point on, an adoptee can either wait for more people to test or can contact their matches hoping that the matches will have information and be helpful. Keep in mind that all the adoptee has is a theory at this point and they are looking to refine their theory or create a new one and then to help narrow their list of parent candidates.

Fortunately, there are tools and processes to help.

What Are the Odds?

One helpful tool to do this is the WATO, What Are the Odds statistical probability tools at DNAPainter.

Using WATO, you create a hypothesis tree as to how the person whose connection you are seeking might be related, plugging them in to different tree locations, as shown below.

Generations WATO

This is not the same example as Smith and Doe, above, but a real family puzzle being worked on by my cousin. Names are blurred for privacy, of course.

Generations WATO2

WATO then provides a statistical analysis of the various options, with only one of the above hypothesis being potentially viable based on the level of DNA matching for the various hypothetical relationships.

DNAPainter Shared cM Tool

If your eyes are glazing over right about now with all of these numbers flying around, you’re not alone.

I’ll distill this process into individual steps to help you understand how this works, and why, starting with another tool provided by DNAPainter, the Shared cM tool that helps you calculate the most likely relationship with another person.

The more closely related you are to a person, the more DNA you will share with them.

DNAPainter has implemented this tool based on the results of Blaine Bettinger’s Shared cM Project where you can enter the amount of DNA that you share with someone to determine the “best fit” relationship, on average, plus the range of expected shared DNA.

Generations DNAPainter Shared cM Project

You, or the test taker, are in the middle and the relationship ranges surround “you.”

For example, you can clearly see that the number of cMs for my Example Adoptee at 3384 is clearly in the Parent or Child range. But wait, it could also be at the very highest end of a half sibling relationship. Other lower cM matches are less specific, so another feature of the DNAPainter tool is a life-saver.

At the top of the page, you can enter the number of matching cMs and the tool will predict the most likely results, based on probability.

Generations 3384

The relationship for 3384 cMs is 100% a parent/child relationship, shown above, but the sibling box is highlighted below because 3384 is the very highest value in the range. This seems to be a slight glitch in the tool. We can summarize by saying that it would be extremely, extremely rare for a 3384 cM match to be a full sibling instead of a parent or child. Hen’s teeth rare.

Generations parent child

Next, let’s look at 226 cM, for our male adoptee which produces the following results:

Generations 226

The following chart graphically shows the possible relationships. The “male adoptee” is actually Mom’s second cousin. This tool is quite accurate.

Generations 226 chart

Now that you’ve seen the tools in action, let’s take a look at the rest of the process.

The Steps to Success

The single biggest predictor of success identifying an unknown person is the number of close matches. Without relatively close matches, the process gets very difficult quickly.

What constitutes a close match and how many close matches do adoptees generally have to work with?

If an adoptee matches someone at a 2nd or 3rd cousin level, what does that really mean to them?

I’ve created the following charts to answer these questions. By the way, this information is relevant to everyone, not just adoptees.

In the chart below, you can view different relationships in the blue legs of the chart descending from the common ancestral couple.

In this example, “You” and the “Other Tester” match at the 4th cousin level sharing 35 cM of DNA. If you look “up” the tree a generation, you can see that the parents of the testers match at the 3rd cousin level and share 74 cM of DNA, the grandparents of the testers match at the 2nd cousin level and share 223 cM of DNA and so forth.

Generations relationship table

In the left column, generations begin being counted with your parents as generation 1. The cumulative number of direct line relatives you have at each generation is shown in the “# Grandparents” column.

Generations relationship levels

Here’s how to read this chart, straight across.

Viewing the “Generation” column, at the 4th generation level, you have 16 great-great-grandparents. Your great-great-grandparent is a first cousin to the the great-great-grandparent of your 4th cousin. Their parents were siblings.

Looking at it this way, it might not seem too difficult to reassemble the descendancy tree of someone 5 generations in the past, but let’s look at it from the other perspective meaning from the perspective of the ancestral couple.

Generations descendants

Couples had roughly 25 years of being reproductively capable and for most of history, birth control was non-existent. If your great-great-great-grandparents, who were born sometime near the year 1800 (the births of mine range from 1785 to 1810) had 5 children who lived, and each of their descendants had 5 children who lived, today each ancestral couple would have 3,125 descendants.

If that same couple had 10 children and 10 lived in each subsequent generation, they would have 100,000 descendants. Accuracy probably lies someplace in-between. That’s still a huge number of descendants for one couple.

That’s JUST for one couple. You have 32 great-great-great-grandparents, or 16 pairs, so multiply 16 times 3,125 for 50,000 descendants or 100,000 times 16 for…are you ready for this…1,600,000 descendants.

Descendants per GGG-grandparent couple at 5 generations Total descendants for 16 GGG-grandparent couples combined
5 children per generation 3,125 50,000
10 children per generation 100,000 1,600,000

NOW you understand why adoptees need to focus on only close matches and why distant matches at the 3rd and 4th cousin level are just too difficult to work with.

By contrast, let’s look at the first cousin row.

Generations descendants 1C.png

At 5 descendants per generation, you’ll have 25 first cousins or 100 first cousins at 10 descendants per generation.

Generations descendants 2C

At second cousins, you’ll have 125 and 1,000 – so reconstructing these trees down to current descendants is still an onerous task but much more doable than from the third or fourth cousin level, especially in smaller families.

The Perfect Scenario

Barring a fortuitous parent or sibling match, the perfect scenario for adoptees and people seeking unknown individuals means that:

  • They have multiple 1st or 2nd cousin matches making tree triangulation to a maternal and paternal group of matches to identify the common ancestors feasible.
  • Their matches have trees that allow the adoptee to construct theories of how they might fit into a family.

Following the two steps above, when sufficient matching and trees have been assembled, the verification steps begin.

  • Adoptees hope that their matches are responsive to communications requesting additional information to either confirm or refute their relationship theory. For example, my mother could tell the male adoptee that he is related on her father’s side of the family based on Family Tree DNA‘s parental “side” assignment. Based on who else the adoptee matches in common with mother, she could probably tell him how he’s related. That information would be hugely beneficial.
  • In a Doe situation where the goal is to identify remains, with a relatively close match, the investigator could contact that match and ask if they know of a missing family member.
  • In a law enforcement situation where strong close-family matches that function as hints lead to potential violent crime suspects, investigators could obtain a piece of trash discarded by the potential suspect to process and compare to the DNA from the crime scene, such as was done in the Golden State Killer case.

If the discarded DNA doesn’t match the crime scene DNA, the person is exonerated as a potential suspect. If the discarded DNA does match the crime scene DNA, investigators would continue to gather non-DNA evidence and/or pick the suspect up for questioning and to obtain a court ordered DNA sample to compare to the DNA from the crime scene in a law enforcement database.

Sometimes DNA is a Waiting Game

I know that on the surface, DNA matching for adoptees and unknown persons sounds simple, and sometimes it is if there is a very close family match.

More often than not, trying to identify unknown persons, especially if the tester doesn’t have multiple close matches is much like assembling a thousand-piece puzzle with no picture on the front of the box.

Sometimes simply waiting for a better match at some point in the future is the only feasible answer. I waited years for my brother, Dave’s family match. You can read his story here and here.

DNA is a waiting game.

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Disclosure

I receive a small contribution when you click on the link to one of the vendors in my articles. This does NOT increase the price you pay but helps me to keep the lights on and this informational blog free for everyone. Please click on the links in the articles or to the vendors below if you are purchasing products or DNA testing.

Thank you so much.

DNA Purchases and Free Transfers

Genealogy Services

Genealogy Research

Concepts – Endogamy and DNA Segments

Members of endogamous populations intermarry for generations, creating many segments that match, especially at small centiMorgan levels. These matching segments occur because they are members of the same population – not because they are genealogically related in a recent or genealogical time-frame.

Said another way, endogamous people are all related to each other in some way because they descend from a small original population whose descendants continued to intermarry without introducing people outside of the community into the genetic line. In other words, the DNA segments of the original population simply keep getting passed around, because there are no new segments being introduced.

If you only have 10 segments at a specific genetic location to begin with, in the original population – then the descendants of those original people can only have some combination of the DNA of those original people until another person is introduced into the mix.

Examples of endogamous populations are Ashkenazi Jews, Native Americans, Acadians, Mennonite, Amish and so forth.

If you have some family lines from an endogamous population, you’ll match with many members of that group. If you are fully endogamous, you will have significantly more matches than people from non-endogamous groups.

I suggest that you read my article, Concepts: The Faces of Endogamy to set the stage for this article.

In this article, I want to provide you with a visual example of what endogamy looks like in a chromosome browser. It doesn’t matter which vendor you use so long as you can drop the cM count to 1, so I’m using FamilyTreeDNA for this example.

I’ve used three people as examples:

  • Non-endogamous European
  • Ashkenazi Jewish
  • Native American (Sioux)

For all testers, I selected their closest match above 200 cM total plus the following 4 for a total of 5 people to compare in the chromosome browser. I have only shown chromosomes 1-8 because I’m trying to convey the concept, not exact details of each chromosome, and 8 chromosomes fit into one screen shot.

If you’re not familiar with the terminology, you can read about cM, centiMorgans, in the article “Concepts – CentiMorgans, SNPs, and Pickin’Crab.”

Let’s take a look at our 3 examples, one at a time.

Non-Endogamous European Individual

The tester is non-endogamous. Four of the 5 individuals are known family members, although none were target tested by the tester.

Endogamy non-endogamous.png

The tester’s matches at 1 cM are shown below:

Endogamy non-endogamous 1cM.png

Note that the grey hashed regions are regions not reported, so no one matches there.

Below, the same 5 matches shown at 7 cM where roughly half of the matches will be identical by chance. Identical by descent segments include identical by population. You can read about the various types of “identical by” segments in the article, “Concepts – Identical by…Descent, State, Population and Chance”.

Endogamy non-endogamous 7cM.png

Ashkenazi Jewish Individual

The tester, along with both of their parents have tested. None of the matches are known or identified relatives.

Endogamy Jewish.png

Even though none of these individuals can be identified, two are related on both sides, maternal and paternal, of the person who tested.

In the chromosome browser, at 1cM, we see the following:

Endogamy Jewish 1cM.png

At 7cM, the following:

Endogamy 7cM.png

Native American Individual

The tester is 15/16 Native from the Sioux tribe. It’s unlikely that their matches are entirely Native, meaning they are not entirely endogamous. None of the matches are known or identified family members.

Endogamy Native.png

At 1 cM shown below:

Endogamy Native 1cM.png

At 7 cM, below:

Endogamy Native 7cM.png

Side by Side

I’ve placed the three 1 cM charts side by side with the non-endogamous to the left, the Jewish in the center and the Native, at right.

endogamy side by side.png

It’s easy to see that the Jewish tester has more 1 cM segments than the non-endogamous tester, and the Native tester more than both of the others.

Summary Comparison Chart

The chart below shows the difference in total number of segments, number of segments between 1 and 6.99 cM, and number of segments at 7 cM or larger. I downloaded these results into a spreadsheet and counted the rows.

Total Segments Total segments at 1 – 6.99 cM Total at 7 or > cM % 7 or >
Non-Endogamous 98 70 28 29
Jewish 168 139 29 17
Native American 310 295 15 5

You’ll note that the non-endogamous individual only has 58% of the number of total segments compared to the Jewish individual, and 32% compared to the Native American individual. The Jewish individual has 54% of the number of segments that the Native person has.

I was initially surprised by the magnitude of this difference, but after thinking about it, I realized that the Native people have been endogamous for a lot longer in the Americas than the Ashkenazi Jewish people in Europe. At least 12,000 years compared to roughly 2000 years, or approximately (at least) 6 times longer. Furthermore, the Native people in the Americans were entirely isolated until the 1400s, with no possibility of outside admixture. Isolation lasted even longer in the tribes that were not coastal, such as the Sioux in the Dakotas.

Note that the Jewish person and non-endogamous person have almost as many 7cM segments as each other, but the Native person has roughly half as many when compared to the other two. That means that because I made my selection starting point based on total cM, and the Native person has a LOT more 1-6.99 cM segments than the others, at that level, there are fewer strong segment matches for the Native individual.

The Native person’s percentage of 7 cM or greater segments is a much smaller percentage of the total segments.

As a percentage, the 7 or greater cM segments are 29% of the non-endogamous person’s total, 17% of the Jewish person’s, but only 5% of the Native person’s total.

Endogamy not only makes a difference when comparing results, but the specific endogamous population along with their history, how heavily endogamous they are, and how long they have been endogamous appears to factor heavily into the comparison as well.

Full or Half Siblings?

Many people are receiving unexpected sibling matches. Everyday on social media, “surprises” are being reported so often that they are no longer surprising – unless of course you’re the people directly involved and then it’s very personal, life-altering and you’re in shock. Staring at a computer screen in stunned disbelief.

Conversely, sometimes that surprise involves people we already know, love and believe to be full siblings – but autosomal DNA testing casts doubt.

If your sibling doesn’t match at all, download your DNA files and upload to another company to verify. This step can be done quickly.

Often people will retest, from scratch, with another company just for the peace of mind of confirming that a sample didn’t get swapped. If a sample was swapped, then another unknown person will match you at the sibling level, because they would be the one with your sibling’s kit. It’s extremely rare, but it has happened.

If the two siblings aren’t biologically related at all, we need to consider that one or both might have been adopted, but if the siblings do match but are predicted as half siblings, the cold fingers of panic wrap themselves around your heart because the ramifications are immediately obvious.

Your full sibling might not be your full sibling. But how can you tell? For sure? Especially when minutes seem like an eternity and your thoughts are riveted on finding the answer.

This article focuses on two tools to resolve the question of half versus full siblingship, plus a third safeguard.

Half Siblings Versus Step-Siblings

For purposes of clarification, a half sibling is a sibling you share only one parent with, while a step-sibling is your step-parent’s child from a relationship with someone other than your parent. Your step-parent marries your parent but is not your parent. You are not genetically related to your step-siblings unless your parent is related to your step-parent.

Parental Testing

Ideally two people who would like to know if they are full or half siblings would have both parents, or both “assumed” parents to compare their results with. However, life is seldom ideal and parents aren’t always available. Not to mention that parents in a situation where there was some doubt might be reluctant to test.

Furthermore, you may elect NOT to have your parents test if your test with your sibling casts doubt on the biological connections within your family. Think long and hard before exposing family secrets that may devastate people and potentially destroy existing relationships. However, this article is about the science of confirming full versus half siblings, not the ethics of what to do with that information. Let your conscience be your guide, because there is no “undo” button.

Ranges Aren’t Perfect

The good news is that autosomal DNA testing gives us the ability to tell full from half-siblings by comparing the siblings to each other, without any parent’s involvement.

Before we have this discussion, let me be very clear that we are NOT talking about using these tools to attempt to discern a relationship between two more distant unknown people. This is only for people who know, or think they know or suspect themselves to be either full or half siblings.

Why?

Because the ranges of the amount of DNA found in people sharing close family relationships varies and can overlap. In other words, different degrees of relationships can be expected to share the same amounts of DNA. Furthermore, except for parents with whom you share exactly 50% of your autosomal DNA (except males don’t share their father’s X chromosome), there is no hard and fast amount of DNA that you share with any relative. It varies and sometimes rather dramatically.

The first few lines of this Relationship Chart, from the 2016 article Concepts – Relationship Predictions, shows both first and second degree relationships (far right column).

Sibling shared cM chart 2016.png

You can see that first degree relations can be parent/child, or full siblings. Second degree relationships can be half siblings, grandparents, aunt/uncle or niece/nephew.

Today’s article is not about how to discern an unknown relation with someone, but how to determine ONLY if two people are half or full siblings to each other. In other words, we’re only trying to discern between rows two and three, above.

As more data was submitted to Blaine Bettinger’s Shared cM Project, the ranges changed as we continued to learn. Blaine’s 2017 results were combined into a useful visual tool at DNAPainter, showing various relationships.

Sibling shared cM DNAPainter.png

Note that in the 2017 version of the Shared cM Project, the high end of the half sibling range of 2312 overlaps with the low end of the full sibling range of 2209 – and that’s before we consider that the people involved might actually be statistical outliers. Outliers, by their very definition are rare, but they do occur. I have seen them, but not often. Blaine wrote about outliers here and here.

Full or Half Siblings?

So, how to we tell the difference, genetically, between full and half siblings?

There are two parts to this equation, plus an optional third safeguard:

  1. Total number of shared cM (centiMorgans)
  2. Fully Identical Regions (FIR) versus Half Identical Regions (HIR)

You can generally get a good idea just from the first part of the equation, but if there is any question, I prefer to download the results to GedMatch so I can confirm using the second part of the equation too.

The answer to this question is NOT something you want to be wrong about.

Total Number of Shared cM

Each child inherits half of each parent’s DNA, but not the same half. Therefore, full siblings will share approximately 50% of the same DNA, and half siblings will share approximately 25% when compared to each other.

You can see the differences on these charts where percentages are converted into cM (centiMorgans) and on the 2017 combined chart here.

I’ve summarized full and half siblings’ shared cMs of DNA from the 2017 chart, below.

Relationship Average Shared cM Range of Shared cM
Half Siblings 1,783 1,317 – 2,312
Full Siblings 2,629 2,209 – 3,394

Fully Identical and Half Identical Regions

Part of the DNA that full siblings inherit will be the exact same DNA from Mom and Dad, meaning that the siblings will match at the same location on their DNA on both Mom’s strand of DNA and Dad’s strand of DNA. These sections are called Fully Identical Regions, or FIR.

Half siblings won’t fully match, except for very small slivers where the nucleotides just happen to be the same (identical by chance) and that will only be for very short segments.

Half siblings will match each other, but only one parent’s side, called Half Identical Regions or HIR.

Roughly, we expect to see about 25% of the DNA of full siblings be fully identical, which means roughly half of their shared DNA is inherited identically from both parents.

Understanding the Concept of Half Identical Versus Fully Identical

To help understand this concept, every person has two strands of DNA, one from each parent. Think of two sides of a street but with the same addresses on both sides. A segment can “live” from 100-150 Main Street, er, I mean chromosome 1 – but you can’t tell just from the address if it’s on Mom’s side of the street or Dad’s.

However, when you match other people, you’ll be able to differentiate which side is which based on family members from that line and who you match in common with your sibling. This an example of why it’s so important to have close family members test.

Any one segment on either strand being compared between between full siblings can:

  • Not match at all, meaning the siblings inherited different DNA from both parents at this location
  • Match on one strand but not the other, meaning the siblings inherited the same DNA from one parent, but different DNA from the other. (Half identical.)
  • Match identically on both, meaning the siblings inherited exactly the same DNA in that location from both parents. (Fully identical.)

I created this chart to show this concept visually, reflecting the random “heads and tails” combination of DNA segments by comparing 4 sets of full siblings with one another.

Sibling full vs half 8 siblings arrows

This chart illustrates the concept of matching where siblings share:

  • No DNA on this segment (red arrow for child 1 and 2, for example)
  • Half identical regions (HIR) where siblings share the DNA from one parent OR the other (green arrow for child 1 and 2, for example, where the siblings share brown from mother)
  • Fully identical regions (FIR) where they share the same segment from BOTH parents so their DNA matches exactly on both strands (black boxed regions)

If a region isn’t either half or fully identical, it means the siblings don’t match on that piece of DNA at all. That’s to be expected in roughly 50% of the time for full siblings, and 75% of the time for half siblings. That’s no problem, unless the siblings don’t match at all, and that’s entirely different, of course.

Let’s look at how the various vendors address half versus full siblings and what tools we have to determine which is which.

Ancestry

Ancestry predicts a relationship range and provides the amount of shared DNA, but offers no tools for customers to differentiate between half versus full siblings. Ancestry has no chromosome browser to facilitate viewing DNA matches but shared matches can sometimes be useful, especially if other close family members have tested.

Sibling Ancestry.png

Update 4-4-2019 – I was contacted by a colleague who works for an Ancestry company, who provided this information: Ancestry is using “Close Family” to designate avuncular, grandparent/grandchild and half-sibling relationships. If you see “Immediate Family “the relationship is a full sibling.

Customers are not able to view the results for ourselves, but according to my colleague, Ancestry is using FIRs and HIRs behind the scenes to make this designation. The Ancestry Matching White Paper is here, dating from 2016.

If Ancestry changes their current labeling in the future, this may not longer be exactly accurate. Hopefully new labeling would provide more clarity. The good news is that you can verify for yourself at GedMatch.

A big thank you to my colleague!

MyHeritage

MyHeritage provides estimated relationships, a chromosome browser and the amount of shared DNA along with triangulation but no specific tool to determine whether another tester is a full or half sibling. One clue can be if one of the siblings has a proven second cousin or closer match that is absent for the other sibling, meaning the siblings and the second cousin (or closer) do not all match with each other.

Sibling MyHeritage.png

Family Tree DNA

At Family Tree DNA, you can see the amount of shared DNA. They also they predict a relationship range, include a chromosome browser, in common matching and family phasing, also called bucketing which sorts your matches into maternal and paternal sides. They offer additional Y DNA testing which can be extremely useful for males.

Sibling FamilyTreeDNA.png

If the two siblings in question are male, a Y DNA test will shed light on the question of whether or not they share the same father (unless the two fathers are half brothers or otherwise closely related on the direct paternal line).

Sibling advanced matches.png

FamilyTreeDNA provides Advanced Matching tools that facilitate combined matching between Y and autosomal DNA.

Sibling bucketing both.png

FamilyTreeDNA’s Family Finder maternal/paternal bucketing tool is helpful because full siblings should be assigned to “both” parents, shown in purple, not just one parent, assuming any third cousins or closer have tested on both sides, or at least on the side in question.

As you can see, on the test above, the tester matches her sister at a level that could be either a high half sibling match, or a low full sibling match. In this case, it’s a full sibling, not only because both parents tested and she matched, but because even before her parents tested, she was already bucketed to both sides based on cousins who had tested on both the maternal and paternal sides of the family.

GedMatch

GedMatch, an upload site, shows the amount of shared DNA as well. Select the One-to-One matching and the “Graph and Position” option, letting the rest of the settings default.

Sibling GedMatch menu.png

GedMatch doesn’t provide predicted relationship ranges as such, but instead estimates the number of generations to the most recent common ancestor – in this case, the parents.

Sibling GedMatch total.png

However, GedMatch does offer an important feature through their chromosome browser that shows fully identical regions.

To illustrate, first, I’m showing two kits below that are known to be full siblings.

The green areas are FIR or Fully Identical Regions which are easy to spot because of the bright green coloring. Yellow indicate half identical matching regions and red means there is no match.

Sibling GedMatch legend.png

Please note that this legend varies slightly between the legacy GedMatch and GedMatch Genesis, but yellow, green, purple and red thankfully remain the same. The blue base indicates an entire region that matches, while the grey indicates an entire region not considered a match..

Sibling GedMatch FIR.png

Fully identical green regions (FIR) above are easy to differentiate when compared with half siblings who share only half identical regions (HIR).

The second example, below, shows two half-siblings that share one parent.

Sibling GedMatch HIR.png

As you can see, there are slivers of green where the nucleotides that both parents contributed to the respective children just happen to be the same for a very short distance on each chromosome. Compared to the full sibling chart, the green looks very different.

The half-sibling small green segments are fully identical by chance or by population, but not identical by descent which would mean the segments are identical because the individuals share both parents. These two people don’t share both parents.

The fully identical regions for full siblings are much more pronounced, in addition to full siblings generally sharing more total DNA.

GedMatch is the easiest and most useful site to work with for determining half versus full siblings by comparing HIR/FIR. I wrote instructions for downloading your DNA from each of the testing vendors at the links below:

Twins

Fraternal twins are the same as regular siblings. They share the same space for 9 months but are genetically siblings. Identical twins, on the other hand, are nearly impossible to tell apart genetically, and for all intents and purposes cannot be distinguished in this type of testing.

Sibling GedMatch identical twin.png

Here’s the same chart for identical twins.

23andMe

23andMe also provides relationship estimates, along with the amount of shared DNA, a chromosome browser that includes triangulation (although they don’t call it that) and a tool to identify full versus half identical regions. 23andMe does not support trees, a critical tool for genealogists.

Unfortunately, 23andMe has become the “last” company that people use for genealogy. Most of their testers seem to be seeking health information today.

If you just happen to have already tested at 23andMe with your siblings, great, because you can use these tools. If you have not tested at 23andMe, simply upload your results from any vendor to GedMatch.

At 23andMe, under the Ancestry, then DNA Relatives tabs, click on your sibling’s match to view genetic information, assuming you both have opted into matching. If you don’t match your sibling, PLEASE be sure you BOTH have completely opted in for matching. I can’t tell you how many panic stricken siblings I’ve coached who weren’t both opted in to matching. If you’re experiencing difficulty, don’t panic. Simply download both people’s files to GedMatch for an easier comparison. You can find 23andMe download instructions here.

Sibling 23andMe HIR.png

Scrolling down, you can see the options for both half and completely identical segments on your chromosomes as compared to your match. Above,  my child matches me completely on half identical regions. This makes perfect sense, of course, because my father and my child’s father are not the same person and are not related.

Conversely, this next match is my identical twin whom I match completely identically on all segments.

Sibling 23andMe FIR.png

Confession – I don’t have an identical twin. This is actually my V3 test compared with my V4 test, but these two tests are in essence identical twin tests.

Unusual Circumstances

The combination of these two tools, DNA matching and half versus fully identical regions generally provides a relatively conclusive answer as to whether two individuals are half or full siblings. Note the words generally and relatively.

There are circumstances that aren’t as clear cut, such as when the father of the second child is a brother or other close relative of the first child’s father – assuming that both children share the same mother. These people are sometimes called three quarters siblings or niblings.

In other situations, the parents are related, sometimes closely, complicating the genetics.

These cases tend to be quite messy and should be unraveled with the help of a professional. I recommend www.dnaadoption.com (free unknown parent search specialists) or Legacy Tree Genealogists (professional genealogists.)

The Final SafeGuard – Just in Case

A third check, should any doubt remain about full versus half siblings, would be to find a relative that is a second cousin or closer on the presumed mother’s side and one on the presumed father’s side, and compare autosomal results of both relatives to both siblings.

There has never been a documented case of second cousins or closer NOT matching each other. I’m unclear about second cousins once removed, or half second cousins, but about 10% of third cousins don’t match. To date, second cousins (or closer) who didn’t match, didn’t match because they weren’t really biological second cousins.

If the two children are full siblings meaning the biological children of both the presumed parents, both siblings will match the 2nd cousin or closer on the mother’s side AND the 2nd cousin or closer on the father’s side as well. If they are not full siblings, one will match only on the second cousin on the common parent’s side.

You can see in the example below that Child 1 and Child 2, full siblings, match both Hezekiah (green), a second cousin from the father’s side, as well as Susan (pink), a second cousin from the mother’s side.

Sibling both sides matching.png

If one of the two children only matches one cousin, and not the other, then the person who doesn’t match the cousin from the father’s side, for example, is not related to the father – although depending on the distance of the relationship, I would seek an additional cousin to test through a different child – just in case.

You can see in the example below that Child 2 matches both Hezekiah (green) and Susan (pink), but Child 1 only matches Susan (pink), from the mother’s side, meaning that Child 1 does not descend from John, so isn’t the child of the Presumed Father (green).
Sibling both sides not matching.png

If neither child matches Hezekiah, that’s a different story. You need to consider the possibility of one of the following:

  • Neither child is the child of the Presumed Father, and could potentially be fathered by different men
  • A break occurred in the genetic line someplace between John and Hezekiah or between John and the Presumed Father.

In other words, the only way this safeguard works as a final check is if at least ONE of the children matches both presumed parents’ lines with a second cousin or closer.

And yes, these types of “biological lineage disruptions” do occur and much more frequently that first believed.

In the End

You may not need this safeguard check when the first and second methodologies, separately or together, are relatively conclusive. Sometimes these decisions about half versus full siblings incorporate non-genetic situational information, but be careful about tainting your scientific information with confirmation bias – meaning unintentionally skewing the information to produce the result that you might desperately want.

When I’m working with a question as emotionally loaded as trying to determine whether people are half or full siblings, I want every extra check and safeguard available – and you will too. I utilize every tool at my disposal so that I don’t inadvertently draw the wrong conclusion.

I want to make sure I’ve looked under every possible rock for evidence. I try to disprove as much as I try to prove. The question of full versus half siblingship is one of the most common topics of the Quick Consults that I offer. Even when people think they know the answer, it’s not uncommon to ask an expert to take a look to confirm. It’s a very emotional topic and sometimes we are just too close to the subject to be rational and objective.

Regardless of the genetic outcome, I hope that you’ll remember that your siblings are your siblings, your parents are your parents (genetic or otherwise) and love is love – regardless of biology. Please don’t lose the compassionate, human aspect of genealogy in the fervor of the hunt.

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