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

RootsTech 2020: It’s a Wrap

Before sharing photos and details about the last three days at RootsTech, I want to provide some general observations.

I expected the attendance to be down this year because of the concern about the Novel Corona Virus. There was a lot of hand-washing and sanitizer, but no hand-wringing.

I don’t think attendance was lagging at all. In fact, this show was larger, based on how my feet feel and general crowd observation than ever before. People appeared to be more engaged too.

According to RootsTech personnel, 4 major vendors pulled out the week before the show opened; 23andMe, LivingDNA, FindMyPast and a book vendor.

I doubt there’s much of a refund policy, so surely something happened in these cases. If you recall, LivingDNA and FindMyPast have a business relationship. 23andMe just laid off a number of people, but then again, so did Ancestry but you’d never know it based on the size of their booth and staffing here.

Family Search has really stepped up their game to modernize, capture stories, scan books and otherwise make genealogy interesting and attractive to everyone.

We got spoiled last year with the big DNA announcements at RootsTech, but nothing of that magnitude was announced this year. That’s not to say there weren’t vendor announcements, there were.

FamilyTreeDNA announced:

  • Their myOrigins Version 3.0 which is significantly updated by adding several worldwide populations, increasing the number from 24 to 90. I wrote about these features here.
  • Adding a myOrigins chromosome browser painted view. I am SOOO excited about this because it makes ethnicity actually useful for genealogy because we can compare specific ethnicity segments with genealogical matches. I can hardly wait.

RootsTech 2020 Sunny Paul

Sunny Morton with Family Tree Magazine interviewing Dr. Paul Maier, FamilyTreeDNA’s population geneticist. You can see the painted chromosome view on the screen behind Dr. Maier.

  • Providing, after initial release, a downloadable ethnicity estimate segment file.
  • Sponsorship of The Million Mito Project, a joint collaborative citizen science project to rewrite the mitochondrial tree of womankind includes team members Dr. Miguel Vilar, Lead Scientist of the National Geographic Genographic Project, Dr. Paul Maier, Population Geneticist at FamilyTreeDNA, Goran Runfeldt, Head of Research and Development at FamilyTreeDNA, and me, DNAeXplain, scientist, genetic genealogist, National Geographic Genographic Affiliate Researcher.

RootsTech 2020 Million Mito

I was honored to make The Million Mito Project announcement Saturday morning, but it was hard for me to contain my enthusiasm until Saturday. This initiative is super-exciting and I’ll be writing about the project, and how you can participate, as soon as I get home and recover just a bit.

  • Michael Sager, aka Mr. Big Y, announced additions to the Y Tree of Mankind in the Demo Theater, including a particularly impressive haplogroup D split.

Rootstech 2020 Sager

RootsTech 2020 Sager 2

RootsTech 2020 Sager hap d

In case anyone is counting, as of last week, the Y tree has 26,600+ named branches and over half a million detected (private variant) SNPs at FamilyTreeDNA waiting for additional testers to be placed on the tree. All I can say is WOW!!! In 2010, a decade ago, there were only 441 Y DNA branches on the entire Y tree. The Y tree has shot up from a twig to an evergreen. I think it’s actually a Sequoia and we just don’t know how large it’s going to grow to be.

RootsTech 2020 FTDNA booth

FamilyTreeDNA stepped up their game with a way-cool new booth that incorporated a lovely presentation area, greatly improved, which featured several guest presenters throughout the conference, including Judy Russell, below.

RootsTech 2020 Judy Russell

Yes, in case anyone is wondering, I DID ask permission to take Judy’s picture, AND to publish it in my article. Just sayin’😊

MyHeritage announced their new photo colorization, MyHeritage in Color, just before RootsTech. I wrote about it, here. At RootsTech MyHeritage had more announcements, including:

  • Enhancements coming soon to the photo colorization program. It was interesting to learn that the colorization project went live in less than 2 months from inception and resulted from an internal “hack-a-thon,” which in the technology industry is a fun think-tank sort of marathon endeavor where ideas flow freely in a competitive environment. Today, over a million photos have been colorized. People LOVE this feature.

RootsTech 2020 MyHeritage booth

One of their booth giveaways was a magnet – of your colorized ancestor’s photo. Conference attendees emailed the photo to a special email address and came by the booth a few minutes later to retrieve their photo magnet.

The photos on the board in front, above, are the colorized photos waiting for their family to pick them up. How fun!!!

  • Fan View for family trees which isn’t just a chart, but dynamic in that you can click on any person and they become the “center.” You can also add to your tree from this view.

RootsTech 2020 MyHeritage fan tree

One of the views is a colorful fan. If you sign on to your MyHeritage account, you’ll be asked if you’d like to see the new fan view. You can read about the new tree features on their blog, here.

  • The release of a MASSIVE 100-year US city directory digitization project that’s more than just imaging and indexing. If you’ve every used city directories, the unique abbreviations in each one will drive you batty. MyHeritage has solved that problem by providing the images, plus the “translation.” They’ve also used artificial intelligence to understand how to search further, incorporating things like spouse, address and more to provide you with not just one year or directory, but linear information that might allow you to infer the death of a spouse, for example. You can read their blog article, here.

RootsTech 2020 MyHeritage city directories

The MyHeritage booth incorporated a very cool feature this year about the Mayflower. Truthfully, I was quite surprised, because the Mayflower is a US thing. MyHeritage is working with folks in Leiden, Netherlands, where some Mayflower family members remained while others continued to what would become Plymouth Colony to prove the connection.

Rootstech 2020 MyHeritage Mayflower virtual

MyHeritage constructed a 3D area where you can sail with the Pilgrims.

I didn’t realize at first, but the chair swivels and as you move, your view in the 3D “goggles” changes to the direction on board the ship where you are looking.

RootsTech 2020 MyHeritage Mayflower virtual 2

The voyage in 1620 was utterly miserable – very rough with a great deal of illness. They did a good job of portraying that, but not “too much” if you get my drift. What you do feel is the utter smallness of the ship in the immense angry ocean.

I wonder how many descendants “sailed with their ancestors” on the virtual Mayflower. Do you have Mayflower ancestors? Mine are William Brewster, his wife, Mary and daughter, Patience along with Stephen Hopkins and his son, Gyles.

Ancestry’s only announcements were:

  • That they are “making things better” by listening and implementing improvements in the DNA area. I’ll forego any commentary because it would be based on their failure to listen and act (for years) about the absence of segment information and a chromosome browser. You’ve guessed it, that’s not mentioned.
  • That the WWII young man Draft Registration cards are now complete and online. Truthfully, I had no idea that the collection I was using online wasn’t complete, which I actually find very upsetting. Ancestry, assuming you actually are listening, how about warning people when they are using a partially complete collection, meaning what portion is and is not complete.
  • Listing content record additions planned for 2020 including the NYC birth index and other state and international records, some of which promise to be very useful. I wonder which states the statewide digitization projects pertain to and what that means, exactly.

OK, now we’re done with vendor announcements, so let’s just take a walk around the expo hall and see who and what we find. We might run into some people you know!

Walking Around

I sandwiched my walking around in-between my sessions. Not only did I present two RootsTech classes, but hosted the ToolMaker Meetup, attended two dinners, two lunches, announced The Million Mito Project, did two booth talks, one for FamilyTreeDNA and one for WikiTree, and I think something else I’ve forgotten about. Plus, all the planned and chance meetings which were absolutely wonderful.

Oh yes, and I attended a couple of sessions myself as an attendee and a few in the vendors booths too.

The great thing, or at least I think its great, is that most of the major vendors also have booth educational learning opportunities with presentation areas at their booths. Unfortunately, there is no centralized area where you can find out which booths have sessions, on what topics, when. Ditto for the Demo Theater.

Of course, that means booth presentations are also competing for your time with the regular sessions – so sometimes it’s really difficult to decide. It’s sort of like you’re awash in education for 4 days and you just can’t absorb enough. By Saturday, you’re physically and emotionally exhausted and you can’t absorb another iota, nor can you walk another step. But then you see someone you know and the pain in your feet is momentarily forgotten.

Please note that there were lots of other people that I saw and we literally passed, hugged and waved, or we were so engrossed in conversation that I didn’t realize until later that I had failed to take the photo. So apologies to all of those people.

RootsTech 2020 Amy Mags

I gave a presentation in the WikiTree booth about how to incorporate WikiTree into your 52 Ancestor stories, both as a research tool and as a way to bait the hook for cousins. Not to mention seeing if someone has already tested for Y or mtDNA, or candidates to do so.

That’s Amy Johnson Crow who started the 52 Ancestors challenge years ago, on the left and Mags Gaulden who writes at Grandma’s Genes and is a WikiTree volunteer (not to mention MitoY DNA.) Amy couldn’t stay for the presentation, so of course, I picked on her in her absence! I suspect her ears were burning. All in a good way of course.

RootsTech 2020 Kevin Borland

Kevin Borland of Borland Genetics, swabbing at the Family Tree DNA  booth, I hope for The Million Mito Project.

RootsTech 2020 Daniel Horowitz

Daniel Horowitz with MyHeritage at the blogger dinner. How about that advertising on his laptop lid. I need to do that with DNAexplain. Wonder where I can get one of those decals custom made.

RootsTech 2020 Hasani

Hasani Carter who I know from Facebook and who I discovered volunteering in a booth at RootsTech. I love to see younger people getting involved and to meet people in person. Love your dreads, Hasani.

RootsTech 2020 Randy Seaver

Cousin Randy Seaver who writes at Genea-Musings, daily, and has for YEARS. Believe it or not, he has published more than 13,000 articles, according to the Lifetime Achievement Award presented by Dear Myrtle at RootsTech. What an incredible legacy.

If you don’t already subscribe (it’s free), you’re missing out. By the way, I discovered Randy was my cousin when I read one of his 52 Ancestors articles, recognizing that his ancestor and my ancestor had the same surname in the same place. He knew the connection. Those articles really work. Thanks Randy – it was so good to see you again.

RootsTech 2020 univ dundee

The University of Dundee booth, with Sylvia Valentine and Pat Whatley, was really fun.  As part of their history and genealogy curriculum (you an earn certificates, bachelors and masters degrees,) they teach paleography, which, in case you are unaware is the official word for deciphering “ancient handwriting.” You didn’t know that’s what you’d been doing did you?

RootsTech 2020 paleography

They provided ink and quills for people to try their own hand.

RootsTech 2020 Paleography 2

The end of the feather quill pen is uneven and scratchy. Pieces separate and splatter ink. You can’t “write,” you draw the letters very, very carefully and slowly. I must say, my “signature” is more legible than normal.

Rootstech 2020 scribe

I now have a lot more empathy for those scribes. It’s probably a good thing that early records are no worse than they are.

RootsTech 2020 Gilad Japhet

Gilad Japhet at the MyHeritage luncheon. I have attended other vendor sponsored (but paid by the attendee) lunches at RootsTech in the past and found them disappointing, especially for the cost. Now MyHeritage is the only sponsored lunch that I attend and I always enjoy it immensely. Yes, I arrived early and sat dead center in front.

I also have a confession to make – I was so very excited about being contacted by Mary Tan Hai’s son that I was finishing colorizing the photos part of the time while Gilad was talking. (I did warn him so he didn’t think I was being rude.) But it’s HIS fault because he made these doggone photos so wonderful – and let’s just say time was short to get the photos to Mary’s family. You can read this amazing story, here.

Gilad always shares part of his own personal family story, and this time was no different. He shared that his mother is turning 85 soon and that the family, meaning her children and grandchildren all teamed up to make her a lovely video. Trust me, it was and made us all smile.

I’m so grateful for a genealogy company run by a genealogist. Speaking of that, Gilad’s mother was a MyHeritage board member in the beginning. That beginning also included a story about how the MyHeritage name came to be, and how Gilad managed to purchase the domain for an unwilling seller. Once again, by proxy, his mother entered into the picture. If you have the opportunity to hear Gilad speak – do – you won’t be disappointed. You’ll hear him speak for sure if you attend MyHeritage LIVE in Tel Aviv this October.

RootsTech 2020 Paul Woodbury

Paul Woodbury who works for Legacy Tree Genealogists, has a degree in both family history and genetics from BYU. He’s standing with Scott Fisher (left). Paul’s an excellent researcher and the only way you can put him to work on your brick wall is through Legacy Tree Genealogists. If you contact them for a quote, tell them I referred you for a $50 discount.

Rootstech 2020 Toolmaker meetup

From The ToolMaker’s Meetup, at far left, Jonny Pearl of DNAPainter, behind me, Dana Leeds who created The Leeds Method, and at right, Rob Warthen, the man behind DNAGedcom. Thanks to Michelle Patient for the photo.

RootsTech 2020 Toolmaker meetup 2

The meetup was well received and afforded people an opportunity to meet and greet, ask questions and provide input.

RootsTech 2020 Campbell baby

In fact, we’re working on recruiting the next generation. I have to say, my “grandma” kicked in and I desperately wanted to hold this beautiful baby girl. What a lovely family. Of course, when I noticed the family name is Campbell, we had a discussion of a different nature, especially since my cousin, Kevin Campbell and I were getting ready to have lunch. We will soon find out if Heidi’s husband is our relative, which makes her and her daughter our relative too!

Rootstech 2020 Kevin Campbell

It was so much fun to sit and develop a research plan with Kevin Campbell. We’re related, somehow on the Campbell line – we just have to sort out when and where.

Bless Your Heart

The photo I cherish most from RootsTech 2020 is the one that’s not pictured here.

A very special gentleman told me, when I asked if we could take a picture together, after he paid me the lovely compliment of saying that my session was the best one he had ever attended, that he doesn’t “do pictures.” Not in years, literally. I thought he was kidding at first, but he was deadly seriously.

The next day, I saw him again a couple of times and we shares stories. Our lives are very different, yet they still intersected in amazing ways. I feel like I’ve known him forever.

Then on the last day, he attended my Million Mito presentation and afterwards came up and told me a new story. How he had changed his mind, and what prompted the change of heart. Now we have a wonderful, lovely photo together which I will cherish all the more because I know how special it is – and how wonderful that makes me feel.

To my friend – you know who you are – thank you! You have blessed my heart. Bless yours😊

The Show Floor

I think I actually got all the way through the show floor, but I’m not positive. In some cases, the “rows” weren’t straight or had dead ends due to large booths, and it was possible to miss an area. I didn’t get to every booth I wanted to. Some were busy, some I simply forgot to take photos.

RootsTech 2020 everything

You can literally find almost anything.

I focused on booths related to genetic genealogy, but not exclusively.

RootsTech 2020 DNAPainter

Jonny Perl and the DNAPainter booth. I’ve written lots of articles, here, about using DNAPainter, one of my very favorite tools.

RootsTech 2020 Rootstech store

The RootsTech store was doing a brisk business.

RootsTech 2020 DNA basics

The RootsTech show area itself had a DNA Basics area which I thought was brilliant in its simplicity.

Inheritance is show by jellybeans.

Rootstech 2020 dNA beans

Put a cup under the outlet and pull the lever.

Rootstech 2020 beans in cup

How many of which color you receive in your cup is random, although you get exactly the same number from the maternal and paternal side.

Now you know I wanted to count these, don’t you?

Rootstech 2020 JellyGenes

And they are of course, called, “JellyGenes.” Those must be deletions still laying in the bin.

RootsTech 2020 Wikitree

WikiTree booth and volunteers. I love WikiTree – it’s “one great tree” is not perfect but these are the people, along with countless others that inject the “quality” into the process.

RootsTech 2020 MitoYDNA

MitoYDNA with Kevin Borland standing in front of the sign.

RootsTech 2020 Crossley

This amazing artist whose name I didn’t get. I was just so struck by her work, painting her ancestor from the picture on her phone.

RootsTech 2020 painter

I wish I was this talented. I would love to have some of my ancestor’s painted. Hmm….

Rootstech 2020 GeneaCreations

Jeanette at GeneaCreations makes double helix zipper pulls, along with lots of other DNA bling, and things not so blingy for men. These are just SOOO cool.

RootsTech 2020 zipper pull

I particularly love my “What’s Your Haplogroup” t-shirt and my own haplogroup t-shirt. Yes, she does custom work. What’s your haplogroup? You can see those goodies here.

Around the corner, I found CelebrateDNA.

RootsTech 2020 Celebrate DNA

Is that a Viking wearing a DNA t-shirt?

Rootstech 2020 day of the dead

CelebrateDNA has some very cool “Day of the Dead” bags, t-shirts and mouse pads, in addition to their other DNA t-shirts. I bought an “Every day is Day of the Dead for Genealogists” mouse pad which will live permanently in my technology travel bag. You can see their other goodies, here.

RootsTech 2020 skeleton

Hey, I think I found a relative. Can we DNA test to see?

Rootstech 2020 Mayflower replica

The Mayflower Society had a fun booth with a replica model ship.

RootsTech 2020 Mayflower passengers

Along with the list of passengers perched on a barrel of the type that likely held food or water for the Pilgrims.

RootsTech 2020 Webinar Marathon

Legacy Family Tree Webinars is going to have a 24-hour Genealogy Webinar Marathon March 12-13. So, who is going to stay up for this?Iit’s free and just take a look at the speakers, and topics, here. I’m guessing lots of people will take advantage of this opportunity. You can also subscribe for more webinars, here.

On March 4th, I’m presenting a FREE webinar, “3 Genealogy DNA Case Studies and How I Solved Them,” so sign up and join in!

Rootstech 2020 street art

Food at RootsTech falls into two categories. Anything purchased in the convention center meaning something to stave off starvation, and some restaurant with friends – the emphasis being on friends.

A small group went for pizza one evening when we were too exhausted to do anything else. Outside I found this interesting street art – and inside Settebello Pizzeria Napoletana I had the best Margarita Pizza I think I’ve ever had.

Then, as if I wasn’t already stuffed to the gills, attached through a doorway in the wall is Capo Gelateria Italiana, creators of artisan gelato. I’ve died and gone to heaven. Seriously, it’s a good thing I don’t live here.

Rootstech 2020 gelatto

Who says you can’t eat ice cold gelato in the dead of winter, outside waiting for the Uber, even if your insides are literally shivering and shaking!! It was that good.

This absolutely MUST BE a RootsTech tradition.

Rootstech 2020 ribbons

That’s it for RootsTech 2020. Hope you’ve enjoyed coming along on this virtual journey and that you’ve found something interesting, perhaps a new hint or tool to utilize.

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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

DNAPainter: Painting “Bucketed” Family Tree DNA Maternal and Paternal Family Finder Matches in One Fell Swoop

DNAPainter has done it again, providing genealogists with a wonderful tool that facilitates separating your matches into maternal and paternal categories so that they can be painted on the proper chromosome – in one fell swoop no less.

Of course, the entire purpose of painting your chromosomes is to identify segments that descend from specific ancestors in order to push those lines back further in time genealogically. Identifying segments, confirming and breaking down brick walls is the name of the game.

DNA Painter New Import Tool

The new DNAPainter tool relies on Family Tree DNA’s Phased Family Matching which assigns your matches to maternal and paternal buckets. On your match list, at the top, you’ll see the following which indicates how many matches you have in total and how many people are assigned to each bucket.

DNAPainter FF import.png

Note that these are individual matches, not total matching segments – that number would be higher.

In order for Family Tree DNA to create bucketed matches for you, you’ll need to:

  • Either create a tree or upload a GEDCOM file
  • Attach your DNA kit to “you” in your tree
  • Attach all 4th cousins and closer with whom you match to their proper location on your tree

Yes, it appears that Family Tree DNA is now using 4th cousins, not just third cousins and closer, which provides for additional bucketed matches.

How reliable is bucketing?

Quite. Occasionally one of two issues arise which becomes evident if you actually compare the matches’ segments to the parent with whom they are bucketed:

  • One or more of your matches’ segments do match you and your parent, but additionally, one or more segments match you, but not your parent
  • The X chromosome is particularly susceptible to this issue, especially with lower cM matches
  • Occasionally, a match that is large enough to be bucketed isn’t, likely because no known, linked cousin shares that segment

Getting Started

Get started by creating or uploading your tree at Family Tree DNA.

DNAPainter mytree.png

After uploading your GEDCOM file or creating your tree at Family Tree DNA, click on the “matches” icon at the top of the tree to link yourself and your relatives to their proper places on your tree. Your matches will show in the box below the helix icon.

DNAPainter FF matches.png

I created an example “twin” for myself to use for teaching purposes by uploading a file from Ancestry, so I’m going to attach that person to my tree as my “Evil Twin.” (Under normal circumstances, I do not recommend uploading duplicate files of anyone.)

DNAPainter FF matches link.png

Just drag and drop the person on your match list on top of their place on the tree.

DNAPainter Ff sister.png

Here I am as my sister, Example Adoptee.

I’ve wished for a very, very long time that there was a way to obtain a list of segment matches sorted by maternal and paternal bucket without having to perform spreadsheet gymnastics, and now there is, at DNAPainter.

DNAPainter does the heavy-lifting so you don’t have to.

What Does DNAPainter Do with Bucketed Matches?

When you are finished uploading two files at DNAPainter, you’ll have:

  • Maternal groups of triangulated matches
  • Paternal groups of triangulated matches
  • Matches that could not be assigned based on the bucketing. Some (but not all) of these matches will be identical by chance – typically roughly 15-20% of your match list. You can read about identical by chance, here.

I’ll walk you through the painting process step by step.

First, you need to be sure your relatives are connected to your tree at Family Tree DNA so that you have matches assigned to your maternal and paternal buckets. The more relatives you connect, per the instructions in the previous section, the more matching people will be able to be placed into maternal or paternal buckets.

Painting Bucketed Matches at DNAPainter

I wrote basic articles about how to use DNAPainter here. If you’re unfamiliar with how to use DNAPainter or it’s new to you, now would be a good time to read those articles. This next section assumes that you’re using DNAPainter. If not, go ahead, register, and set up a profile. One profile is free for everyone, but multiple profiles require a subscription.

First, make a duplicate of the profile that you’re working with. This DNAPainter upload tool is in beta.

DNAPainter duplicate profile.png

Since I’m teaching and experimenting, I am using a fresh, new profile for this experiment. If it works successfully, I’ll duplicate my working profile, just in case something goes wrong or doesn’t generate the results I expect, and repeat these steps there.

Second, at Family Tree DNA, Download a fresh copy of your complete matching segment file. This “Download Segments” link is found at the top right of the chromosome browser page.

DNAPainter ff download segments.png

Third, download your matches at the bottom left of the actual matches page. This file hold information about your matches, such as which ones are bucketed, but no segment information. That’s in the other file.

DNAPainter csv.png

Name both of these files something you can easily identify and that tells them apart. I called the first one “Segments” in front of the file name and the second one “Matches” in front of the file name.

Fourth, at DNAPainter, you’ll need to import your entire downloaded segment file that you just downloaded from Family Tree DNA. I exclude segments under 7cM because they are about 50% identical by chance.

DNAPainter import instructions

click to enlarge

Select the segment file you just named and click on import.

DNAPainter both.png

At this point, your chromosomes at DNAPainter will look like this, assuming you’re using a new profile with nothing else painted.

Let’s expand chromosome 1 and see what it looks like.

DNAPainter chr 1 both.png

Note that all segments are painted over both chromosomes, meaning both the maternal and paternal copies of chromosome 1, partially shown above, because at this point, DNAPainter can’t tell which people match on the maternal and which people match on the paternal sides. The second “matches” file from Family Tree DNA has not yet been imported into DNAPainter, which tells DNAPainter which matches are on the maternal and which are on the paternal chromosomes.

If you’re not workign with a new profile, then you’ll also see the segments you’ve already painted. DNAPainter attempts to NOT paint segments that appear to have previously been painted.

Fifth, at DNAPainter, click on the “Import mat/pat info from ftDNA” link on the left which will provide you with a page to import the matches file information. This is the file that has maternal and paternal sides specified for bucketed matches. DNAPainter needs both the segment file, which you already imported, and the matches file.

DNAPainter import bucket

click to enlarge

After the second import, the “matches” file, my matches are magically redistributed onto their appropriate chromosomes based on the maternal and paternal bucketing information.

I love this tool!

At this point, you will have three groups of matches, assuming you have people assigned to your maternal and paternal buckets.

  • A “Shared” group for people who are related to both of your parents, or who aren’t designated as a bucketed match to either parent
  • Maternal group (pink chromosome)
  • Paternal group (blue chromosome)

It’s Soup!!!

I’m so excited. Now my matches are divided into maternal and paternal chromosome groups.

DNAPainter import complete.png

Just so you know, I changed the colors of my legend at DNAPainter using “edit group,” because all three groups were shades of pink after the import and I wanted to be able to see the difference clearly.

DNAPainter legend.png

Your Painted Chromosomes

Let’s take a look at what we have.

DNAPainter both, mat, pat.png

There’s still pink showing, meaning undetermined, which gets painted over both the maternal and paternal chromosomes, but there’s also a lot of magenta (maternal) and blue (paternal) showing now too as a result of bucketing.

Let’s look at chromosome 1.

DNAPainter chr 1 all.png

This detail, which is actually a summary, shows that the bucketed maternal (magenta) and paternal (blue) matches have actually covered most of the chromosome. There are still a few areas without coverage, but not many.

For a genealogist, this is beautiful!!!

How many matches were painted?

DNAPainter paternal total.png

DNAPainter maternal total.png

Expanding chromosome 1, and scrolling to the maternal portion, I can now see that I have several painted maternal segments, and almost the entire chromosome is covered.

Here’s the exciting part!

DNAPainter ch1 1 mat expanded.png

I stared the relatives I know, on the painting, above and on the pedigree chart, below. The green group descends through Hiram Ferverda and Eva Miller, the yellow group through Antoine Lore and Rachel Hill. The blue group is Acadian, upstream of Antoine Lore.

DNAPainter maternal pedigree.png

Those ancestors are shown by star color on my pedigree chart.

I can now focus on the genealogies of the other unstarred people to see if their genealogy can push those segments back further in time to older ancestors.

On my Dad’s side, the first part of chromosome 1 is equally as exciting.

DNAPainter chr 1 pat expanded.png

The yellow star only pushed this triangulated group back only to my grandparents, but the green star is from a cousin descended from my great-grandparents. The red star matches are even more exciting, because my common ancestor with Lawson is my brick wall – Marcus Younger and his wife, Susanna, surname unknown, parents of Mary Younger.

DNAPainter paternal pedigree.png

I need to really focus hard on this cluster of 12 people because THEIR common ancestors in their trees may well provide the key I need to push back another generation – through the brick wall. That is, after all, the goal of genetic genealogy.

Woohoooo!

Manual Spreadsheet Compare

Because I decided to torture myself one mid-winter day, and night, I wanted to see how much difference there is between the bucketed matches that I just painted and actual matches that I’ve identified by downloading my parents’ segment match files and mine and comparing them manually against each other. I removed any matches in my file that were not matches to my parent, in addition to me, then painted the rest.

I’ll import the resulting manual spreadsheet into the same experimental DNAPainter profile so we can view matches that were NOT painted previously. DNAPainter does not paint matches previously painted, if it can tell the difference. Since both of these files are from downloads, without the name of the matches being in any way modified, DNAPainter should be able to recognize everyone and only paint new segment matches.

Please note here that the PERSON unquestionably belongs bucketed to the parental side in question, but not all SEGMENTS necessarily match you and your parent. Some will not, and those are the segments that I removed from my spreadsheet.

DNAPainter manual spreadsheet example.png

Here’s a made-up example where I’ve combined my matches and my mother’s matches in one spreadsheet in order to facilitate this comparison. I colored my Mom’s matches green so they are easy to see when comparing to my own, then sorting by the match name.

Person 1 matches me and Mom both, at 10 cM on chromosome 1. Person 1 is assigned to my maternal side due to the matches above 9 cM, the lowest threshold at Family Tree DNA for bucketing.

In this example, we can see that Person 1 matches me and Mom (colored green), both, on the segment on chromosome 1. That match, bracketed by red, is a valid, phased, match and should be painted.

However, Person 1 also matches me, but NOT Mom on chromosome 2. Because Person 1 is bucketed to mother, this segment on chromosome 2 will also be painted to my maternal chromosome 2 using the DNAPainter import. The only way to sort this out is to do the comparison manually.

The same holds true for the X match shown. The two segments shown in red should NOT be painted, but they will be unless you are willing to compare you and your parents’ matches manually, you will just have to evaluate segments individually when you see that you’re working in a cluster where matches have been assigned through the mass import tool.

If you choose to compare the spreadsheets manually to assure that you’re not painting segments like the red ones above, DNAPainter provides instructions for you to create your own mass upload template, which is what I did after removing any segment matches of people that were not “in common” between me and mother on the same chromosomal segment, like the red ones, above.

Please note that if you delete the erroneous segments and later reimport your bucketed matches, they will appear again. I’m more inclined to leave them, making a note.

I did not do a manual comparison of my father’s side of the tree after discovering just how little difference was found on my mother’s side, and how much effort was involved in the manual comparison.

Creating a Mass Upload Template and File

DNAPainter custom mass upload.png

The instructions for creating your own mass upload file are provided by DNAPainter – please follow them exactly.

In my case, after doing the manual spreadsheet compare with my mother, only a total of 18 new segments were imported that were not previously identified by bucketing.

Three of those segments were over 15cM, but the rest were smaller. I expected there would be more. Family Tree DNA is clearly doing a great job with maternal and paternal bucketing assignments, but they can’t do it without known relatives that have also tested and are linked to your tree. The very small discrepancy is likely due to matches with cousins that I have not been able to link on my tree.

The great news is that because DNAPainter recognizes already-painted segments, I can repeat this anytime and just paint the new segments, without worrying about duplicates.

  • The information above pertains to segments that should have been painted, but weren’t.
  • The information below pertains to segments that were painted, but should not have been.

I did not keep track of how many segments I deleted that would have erroneously been painted. There were certainly more than 18, but not an overwhelming number. Enough though to let me know to be careful and confirm the segment match individually before using any of the mass uploaded matches for hypothesis or conclusions.

Given that this experiment went well, I created a copy of my “real” profile in order to do the same import and see what discoveries are waiting!

Before and After

Before I did the imports into my “real” file (after making a copy, of course,) I had painted 82% of my DNA using 1700 segments. Of course, each one of those segments in my original profile is identified with an ancestor, even if they aren’t very far back in time.

Although I didn’t paint matches in common with my mother before this mass import, each of my matches in common with my mother are in common with one or the other of my maternal grandparents – and by using other known matches I can likely push the identity of those segments further back in time.

Status Percent Segments Painted
Before mass Phased Family Match bucketed import 82 1700
After mass Phased Family Match bucketed import 88 7123
After additional manual matches with my mother added 88 7141

While I did receive 18 additional matching segments by utilizing the manually intensive spreadsheet matching and removal process, I did not receive enough more matches to justify the hours and hours of work. I won’t be doing that anymore with Family Tree DNA files since they have so graciously provided bucketing and DNAPainter can leverage that functionality.

Those hours will be much better spent focusing on unraveling the ancestors whose stories are told in clusters of triangulated matches.

I Love The Import Tool, But It’s Not Perfect

Keep in mind that the X chromosome needs a match of approximately twice the size of a regular chromosome to be as reliable. In other words, a 14 cM threshold for the X chromosome is roughly equivalent to a 7 cM match for any other chromosome. Said another way, a 7 cM match on the X is about equal to a 3.5 cM match on any other chromosome.

X matches are not created equal.

The SNP density on the X chromosome is about half that of the other chromosomes, making it virtually impossible to use the same matching criteria. I don’t encourage using matches of less than 500 SNPs unless you know you’re in a triangulated group and WITH at least a few larger, proven matches on that segment of the X chromosome.

Having said that, X matches, due to their unique inheritance path can persist for many generations and be extremely useful. You can read about working with the X chromosome here and here.

I noticed when I was comparing segments in the manual spreadsheet that I had to remove many X matches with people who had identical matches on other chromosomes with me and my mother. In other words, just because they matched my mother and me exactly on one chromosome, that phasing did not, by default, extend to matching on other segments.

I checked my manually curated file and discovered that I had a total of seven X matches that should have been, and were, painted because they matched me and Mom both.

DNAPainter X spreadsheet example.png

However, there were many that didn’t match me and Mom both, matching only me, that were painted because that person was bucketed (assigned) to my maternal side because a different segment phased to mother correctly.

On the X chromosome, here’s what happened.

DNAPainter maternal X.png

You can see that a lot more than 7 bright red matches were painted – 26 more to be exact. That’s because if an individual is bucketed on your maternal or paternal side, it’s presumed that all of the matching segments come from the same ancestor and are legitimate, meaning identical by descent and not by chance. They aren’t. Every single segment has an inheritance path and story of its own – and just because one segment triangulates does NOT mean that other segments that match that person will triangulate as well.

The X chromosome is the worst case scenario of course, because these 7 cM segments are actually as reliable as roughly 3.5 cM segments on any other chromosome, which is to say that more than 50% of them will be incorrect. However, some will be accurate and those will match me and mother both. 21% of the X matches to people who phased and triangulated on other chromosomes were accurate – 79% were not. Thankfully, we have phasing, bucketing and tools like this to be able to tell the difference so we can utilize the 21% that are accurate. No one wants to throw the baby out with the bath water, nor do we want to chase after phantoms.

Keep in mind that Phased Family Matching, like any other tool, is just that, a tool and needs some level of critical analysis.

Every Segment Has Its Own Story

We know that every single DNA segment has an independent inheritance path and story of its own. (Yes, I’ve said that several time now because it’s critically important so that you don’t wind up barking up the wrong tree, literally, pardon the pun.)

In the graphic above of my painted X chromosome matches, only the six matches with green stars are on the hand-curated match list. One had already been painted previously. The balance of the bright red matches were a part of the mass import and need to be deleted. Additionally, one of the accurate matches did not upload for some reason, so I’ll add that one manually.

I suggest that you go ahead and paint your bucketed segments, but understand that you may have a red herring or two in your crop of painted segment matches.

As you begin to work with these clusters of matches, check your matching segments with your parents (or other family members who were used in bucketing) and make sure that all the segments that have been painted by bulk upload actually match on all of the same segments.

If you have a parent that tested, there is no need to see if you and your match match other relatives on that same side. If your match does not match you and your parent on some significant overlapping portion of that same segment, the match is invalid. DNA does not “skip generations.”

If you don’t have a parent that has tested, your known relatives are your salvation, and the key to bucketed matches.

The great news is that you can easily see that a bulk match was painted from the coloring of the batch import. As you discover the relevant genealogy and confirm that all segments actually match your parent (or another family member, if you don’t have parents to test,) move the matching person to the appropriately colored ancestral group.

I further recommend that you hand curate the X chromosome using a spreadsheet. The nature of the X makes depending on phased matching too risky, especially with a tool like DNAPainter that can’t differentiate between a legitimate and non-legitimate match. The X chromosome matches are extraordinarily valuable because they can be useful in ways that other chromosomes can’t be due to the X’s unique inheritance path.

What About You?

If you don’t have your DNA at Family Tree DNA and you have tested elsewhere, you can transfer your DNA file for free, allowing you to see your matches and use many of the Family Tree DNA tools. However, to access the chromosome browser, which you’ll need for DNA painting, you’ll need to purchase the unlock for $19, but that’s still a lot less than retesting.

Here are transfer instructions for transferring your DNA file from 23andMe, Ancestry or MyHeritage.

If you have not purchased a Family Finder test at Family Tree DNA and don’t have a DNA file to transfer, you can order a test 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 Products and Services

Genealogy Research

Fun DNA Stuff

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

Crossovers: Frequency and Inheritance Statistics – Male Versus Female Matters

Recently, a reader asked if I had any crossover statistics.

They were asking about the number of crossovers, meaning divisions on each chromosome, of the parent’s DNA when a child is created. In other words, how many segments of your maternal and paternal grandparent’s DNA do you inherit from your mother and father – and are those numbers somehow different?

Why would someone ask that question, and how is it relevant for genealogists?

What is a Crossover and Why is it Important?

We know that every child receives half of their autosomal DNA from their father, and half from their mother. Conversely that means that each parent can only give their child half of their own DNA that they received from their parents. Therefore, each parent has to combine some of the DNA from their father’s chromosome and their mother’s chromosome into a new chromosome that they contribute to their child.

Crossovers are breakpoints that are created when the DNA of the person’s parents is divided into pieces before being recombined into a new chromosome and passed on to the person’s child.

I’m going to use the following real-life scenario to illustrate.

Crossover pedigree.png

The colors of the people above are reflected on the chromosome below where the DNA of the blue daughter, and her red and green parents are compared to the DNA of the tester. The tester is shown as the gray background chromosomes in the chromosome browser. The backgroud person is whose results we are looking at.

My granddaughter has tested her DNA, as have her parents and 3 of her 4 grandparents along with 2 great-grandparents, shown as red and green in the diagram above.

Here’s an example utilizing the FamilyTreeDNA chromosome browser.

Crossover example chr 1.png

On my granddaughter’s chromosome 1, on the chromosome brower above, we see two perfect examples of crossovers.

There’s no need to compare her DNA against that of her parent, the son in the chart above, because we already know she matches the full length of every chromosome with both of her parents.

However, when comparing my granddaughter’s DNA against the grandmother (blue) and her grandmother’s parents, the great-grandmother shown in red and great-grandfather shown in green, we can see that the granddaughter received her blue segments from the grandmother.

The grandmother had to receive that entire blue segment from either her mother, in red, or her father, in green. So, every blue segment must have an exactly matching red segment, green segment or combination of both.

The first red box at left shows that the blue segment was inherited partially from the grandmother’s red mother and green father. We know that because the tester matches the red great-grandmother on part of that blue segment and the green great-grandfather on a different part of the entire blue segment that the tester inherited from her blue grandmother.

The middle colored region, not boxed, shows the entire blue segment was inherited from the red great-grandmother and the blue grandmother passed that intact through her son to her granddaughter.

The third larger red boxed area encompassing the entire tested region to the right of the centromere was inherited by the granddaughter from her grandmother (blue segment) but it was originally from the blue grandmother’s red mother and green father.

The Crossover

The areas on this chromosome where the blue is divided between the red and green, meaning where the red and green butt up against each other is called a crossover. It’s literally where the DNA of the blue daughter crosses over between DNA contributed by her red mother and green father.

Crossover segments.png

In other words, the crossover where the DNA divided between the blue grandmother’s parents when the grandmother’s son was created is shown by the dark arrows above. The son gave his daughter that exact same segment from his mother and it’s only by comparing the tester’s DNA against her great-grandparents that we can see the crossover.

Crossover 4 generations.png

What we’re really seeing is that the segments inherited by the grandmother from her parents two different chromosomes were combined into one segment that the grandmother gave to her son. The son inherited the green piece and the red piece on his maternal chromosome, which he gave intact to his daughter, which is why the daughter matches her grandmother on that entire blue segment and matches her great-grandparents on the red and green pieces of their individual DNA.

Inferred Matching Segments

Crossover untested grandfather.png

The entirely uncolored regions are where the tester does not match her blue grandmother and where she would match her grandfather, who has not tested, instead of her blue grandmother.

The testers father only received his DNA from his mother and father, and if his daughter does not match his mother, then she must match his untested father on that segment.

Looking at the Big Inheritance Picture

The tester’s full autosomal match between the blue grandmother, red great-grandmother and green great-grandfather is shown below.

Crossover autosomes.png

In light of the discussion that follows, it’s worth noting that chromosomes 4 and 20 (orange arrows) were passed intact from the blue grandmother to the tester through two meiosis (inheritance) events. We know this because the tester matches the green great-grandfather’s DNA entirely on these two chromosomes that he passed to his blue daughter, her son and then the tester.

Let’s track this for chromosomes 4 and 20:

  • Meiosis 1 –The tester matches her blue grandmother, so we know that there was no crossover on that segment between the father and the tester.
  • Meiosis 2 – The tester matches her green great-grandfather along the entire chromosome, proving that it was passed intact from the grandmother to the tester’s father, her son.
  • What we don’t know is whether there were any crossovers between the green great-grandfather when he passed his parent or parents DNA to the blue grandmother, his daughter. In order to determine that, we would need at least one of the green great-grandfather’s parents, which we don’t have. We don’t know if the green great-grandfather passed on his maternal or paternal copy of his chromosome, or parts of each to the blue great-grandmother, his daughter.

Meiosis Events and the Tree

So let’s look at these meiosis or inheritance events in a different way, beginning at the bottom with the pink tester and counting backwards, or up the tree.

Crossover meiosis events.png

By inference, we know that chromosomes 11, 16 and 22 (purple arrows) were also passed intact, but not from the blue grandmother. The tester’s father passed his father’s chromosome intact to his daughter. That’s the untested grandfather again. We know this because the tester does not match her blue grandmother at all on either of these three chromosomes, so the tester must match her untested grandfather instead, because those are the only two sources of DNA for the tester’s father.

A Blip, or Not?

If you’ve noticed that chromosome 14 looks unusual, in that the tester matches her grandmother’s blue segment, but not either of her great-grandparents, which is impossible, give yourself extra points for your good eye.

In this case, the green great-grandfather’s kit was a transfer kit in which that portion of chromosome 14 was not included or did not read accurately. Given that the red great-grandmother’s kit DID read in that region and does not match the tester, we know that chromosome 14 would actually have a matching green segment exactly the size of the blue segment.

However, in another situation where we didn’t know of an issue with the transfer kit, it is also possible that the granddaughter matched a small segment of the blue grandmother’s DNA where they were identical by chance. In that case, chromosome 14 would actually have been passed to the tester intact from her father’s father, who is untested.

Every Segment has a Story

Looking at this matching pattern and our ability to determine the source of the DNA back several generations, originating from great-grandparents, I hope you’re beginning to get a sense of why understanding crossovers better is important to genealogists.

Every single segment has a story and that story is comprised of crossovers where the DNA of our ancestors is combined in their offspring. Today, we see the evidence of these historical genetic meiosis or division/recombination events in the start and end points of matches to our genetic cousins. Every start and end point represents a crossover sometime in the past.

What else can we tell about these events and how often they occur?

Of the 22 autosomes, not counting the X chromosome which has a unique inheritance pattern, 17 chromosomes experienced at least one crossover.

What does this mean to me as a genealogist and how can I interpret this type of information?

Philip Gammon

You may remember our statistician friend Philip Gammon. Philip and I have collaborated before authoring the following articles where Philip did the heavy lifting.

I discussed crossovers in the article Concepts – DNA Recombination and Crossovers, also in collaboration with Philip, and showed several examples in a Four Generation Inheritance Study.

If you haven’t read those articles, now might be a good time to do so, as they set the stage for understanding the rest of this article.

The frequency of chromosome segment divisions and their resulting crossovers are key to understanding how recombination occurs, which is key to understanding how far back in time a common ancestor between you and a match can expect to be found.

In other words, everything we think we know about relationships, especially more distant relationships, is predicated on the rate that crossovers occur.

The Concepts article references the Chowdhury paper and revealed that females average about 42 crossovers per child and males average about 27 but these quantities refer to the total number of crossovers on all 22 autosomes and reveal nothing about the distribution of the number of crossovers at the individual chromosome level.

Philip Gammon has been taking a closer look at this particular issue and has done some very interesting crossover simulations by chromosome, which are different sizes, as he reports beginning here.

Crossover Statistics by Philip Gammon

For chromosomes there is surprisingly little information available regarding the variation in the number of crossovers experienced during meiosis, the process of cell division that results in the production of ova and sperm cells. In the scientific literature I have been able to find only one reference that provides a table showing a frequency distribution for the number of crossovers by chromosome.

The paper Broad-Scale Recombination Patterns Underlying Proper Disjunction in Humans by Fledel-Alon et al in 2009 contains this information tucked away at the back of the “Supplementary methods, figures, and tables” section. It was likely not produced with genetic genealogists in mind but could be of great interest to some. The columns X0 to X8 refer to the number of crossovers on each chromosome that were measured in parental transmissions. Separate tables are shown for male and female transmissions because the rates between the two sexes differ significantly. Note that it’s the gender of the parent that matters, not the child. The sample size is quite small, containing only 288 occurrences for each gender.

A few years ago I stumbled across a paper titled Escape from crossover interference increases with maternal age by Campbell et al 2015. This study investigated the properties of crossover placement utilising family groups contained within the database of the direct-to-consumer genetic testing company 23andMe. In total more than 645,000 well-supported crossover events were able to be identified. Although this study didn’t directly report the observed frequency distribution of crossovers per chromosome, it did produce a table of parameters that accurately described the distribution of inter-crossover distances for each chromosome.

By introducing these parameters into a model that I had developed to implement the equations described by Housworth and Stahl in their 2003 paper Crossover Interference in Humans I was able to derive tables depicting the frequency of crossovers. The following results were produced for each chromosome by running 100,000 simulations in my crossover model:

Crossover transmissions from female to child.png

Transmissions from female parent to child, above.

Crossover transmissions male to child.png

Transmissions from male parent to child.

To be sure that we understand what these tables are revealing let’s look at the first row of the female table. The most frequent outcome for chromosome #1 is that there will be three crossovers and this occurs 27% of the time. There were instances when up to 10 crossovers were observed in a single meiosis but these were extremely rare. Cells that are blank recorded no observations in the 100,000 simulations. On average there are 3.36 crossovers observed on chromosome #1 in female to child transmissions i.e. the female chromosome #1 is 3.36 Morgans (336 centimorgans) in genetic length.

Blaine Bettinger has since examined crossover statistics using crowdsourced data in The Recombination Project: Analyzing Recombination Frequencies Using Crowdsourced Data, but only for females. His sample size was 250 maternal transmissions and Table 2 in the report presents the results in the same format as the tables above. There is a remarkable degree of conformity between Blaine’s measurements and the output from my simulation model and also to the earlier Fledel-Alon et al study.

The diagrams below are a typical representation of the chromosomes inherited by a child.

Crossovers inherited from mother.jpg

The red and orange (above) are the set of chromosomes inherited from the mother and the aqua and green (below) from the father. The locations where the colours change identify the crossover points.

It’s worth noting that all chromosomes have a chance of being passed from parent to child without recombination. These probabilities are found in the column for zero crossovers.

In the picture above the mother has passed on two red chromosomes (#14 and #20) without recombination from one of the maternal grandparents. No yellow chromosomes were passed intact.

Similarly, below, the father has passed on a total of five chromosomes that have no crossover points. Blue chromosomes #15, #18 and #21 were passed on intact from one paternal grandparent and green chromosomes #4 and #20 from the other.

Crossovers inherited from father.jpg

It’s quite a rare event for one of the larger chromosomes to be passed on without recombination (only a 1.4% probability for chromosome #1 in female transmissions) but occurs far more frequently in the smaller chromosomes. In fact, the male chromosome #21 is passed on intact more often (50.6% of the time) than containing DNA from both of the father’s parents.

However, there is nothing especially significant about chromosome #21.

The same could be said for any region of similar genetic length on any of the autosomes i.e. the first 52 cM of chromosome #1 or the middle 52 cM of chromosome #10 etc. From my simulations I have observed that on average 2.8 autosomes are passed down from a mother to child without a crossover and an average of 5.1 autosomes from a father to child.

In total (from both parents), 94% of offspring will inherit between 4 and 12 chromosomes containing DNA exclusively from a single grandparent. In the 100,000 simulations the child always inherited at least one chromosome without recombination.

Back to Roberta

If you have 3 generations who have tested, you can view the crossovers in the grandchild as compared to either one or two grandparents.

If the child doesn’t match one grandparent, even if their other grandparent through that parent hasn’t tested, you can certainly infer that any DNA where the grandchild doesn’t match the available grandparent comes from the non-tested “other” grandparent on that side.

Let’s Look at Real-Life Examples

Using the example of my 2 granddaughters, both of their parents and 3 of their 4 grandparents have tested, so I was able to measure the crossovers that my granddaughters experienced from all 4 of their grandparents.

Maternal Crossovers Granddaughter 1 Granddaughter 2 Average
Chromosome 1 6 2 3.36
Chromosome 2 4 2 3.17
Chromosome 3 3 2 2.71
Chromosome 4 2 2 2.59
Chromosome 5 2 1 2.49
Chromosome 6 4 2 2.36
Chromosome 7 3 1 2.23
Chromosome 8 2 2 2.11
Chromosome 9 3 1 1.95
Chromosome 10 4 2 2.08
Chromosome 11 3 0 1.93
Chromosome 12 3 3 2.00
Chromosome 13 1 1 1.52
Chromosome 14 3 1 1.38
Chromosome 15 4 1 1.44
Chromosome 16 2 2 1.58
Chromosome 17 2 2 1.53
Chromosome 18 2 0 1.40
Chromosome 19 2 1 1.18
Chromosome 20 0 1 1.19
Chromosome 21 0 1 0.74
Chromosome 22 1 0 0.78
Total 56 30 41.71

Looking at these results, it’s easy to see just how different inheritance between two full siblings can be. Granddaughter 1 has 56 crossovers through her mother, significantly more than the average of 41.71. Granddaughter 2 has 30, significantly less than average.

The average of the 2 girls is 43, very close to the total average of 41.71.

Note that one child received 2 chromosomes intact from her mother, and the other received 3.

Paternal Crossovers Granddaughter 1 Granddaughter 2 Average
Chromosome 1 2 2 1.98
Chromosome 2 3 2 1.85
Chromosome 3 2 2 1.64
Chromosome 4 0 1 1.46
Chromosome 5 1 2 1.46
Chromosome 6 2 1 1.41
Chromosome 7 1 2 1.36
Chromosome 8 1 1 1.23
Chromosome 9 1 3 1.26
Chromosome 10 3 2 1.30
Chromosome 11 0 1 1.20
Chromosome 12 1 1 1.32
Chromosome 13 2 1 1.02
Chromosome 14 1 0 0.97
Chromosome 15 1 2 1.01
Chromosome 16 0 1 1.02
Chromosome 17 0 0 1.06
Chromosome 18 1 1 0.98
Chromosome 19 1 1 1.00
Chromosome 20 0 0 0.99
Chromosome 21 0 0 0.52
Chromosome 22 0 0 0.63
Total 23 26 26.65

Granddaughter 2 had slightly more paternal crossovers than did granddaughter 1.

One child received 7 chromosomes intact from her father, and the other received 5.

Chromosome Granddaughter 1 Maternal Granddaughter 1 Paternal
Chromosome 1 6 2
Chromosome 2 4 3
Chromosome 3 3 2
Chromosome 4 2 0
Chromosome 5 2 1
Chromosome 6 4 2
Chromosome 7 3 1
Chromosome 8 2 1
Chromosome 9 3 1
Chromosome 10 4 3
Chromosome 11 3 0
Chromosome 12 3 1
Chromosome 13 1 2
Chromosome 14 3 1
Chromosome 15 4 1
Chromosome 16 2 0
Chromosome 17 2 0
Chromosome 18 2 1
Chromosome 19 2 1
Chromosome 20 0 0
Chromosome 21 0 0
Chromosome 22 1 0
Total 56 23

Comparing each child’s maternal and paternal crossovers side by side, we can see that Granddaughter 1 has more than double the number of maternal as compared to paternal crossovers, while Granddaughter 2 only had slightly more.

Chromosome Granddaughter 2 Maternal Granddaughter 2 Paternal
Chromosome 1 2 2
Chromosome 2 2 2
Chromosome 3 2 2
Chromosome 4 2 1
Chromosome 5 1 2
Chromosome 6 2 1
Chromosome 7 1 2
Chromosome 8 2 1
Chromosome 9 1 3
Chromosome 10 2 2
Chromosome 11 0 1
Chromosome 12 3 1
Chromosome 13 1 1
Chromosome 14 1 0
Chromosome 15 1 2
Chromosome 16 2 1
Chromosome 17 2 0
Chromosome 18 0 1
Chromosome 19 1 1
Chromosome 20 1 0
Chromosome 21 1 0
Chromosome 22 0 0
Total 30 26

Granddaughter 2 has closer to the same number of maternal and paternal of crossovers, but about 8% more maternal.

Comparing Maternal and Paternal Crossover Rates

Given that males clearly have a much, much lower crossover rate, according to the Philip’s chart as well as the evidence in just these two individual cases, over time, we would expect to see the DNA segments significantly LESS broken up in male to male transmissions, especially an entire line of male to male transmissions, as compared to female to female linear transmissions. This means we can expect to see larger intact shared segments in a male to male transmission line as compared to a female to female transmission line.

  G1 Mat G2 Mat Mat Avg G1 Pat G2 Pat Pat Avg
Gen 1 56 30 41.71 23 26 26.65
Gen 2 112 60 83.42 46 52 53.30
Gen 3 168 90 125.13 69 78 79.95
Gen 4 224 120 166.84 92 104 106.60

Using the Transmission rates for Granddaughter 1, Granddaughter 2, and the average calculated by Philip, it’s easy to see the cumulative expected average number of crossovers vary dramatically in every generation.

By the 4th generation, the maternal crossovers seen in someone entirely maternally descended at the rate of Grandchild 1 would equal 224 crossovers meaning that the descendant’s DNA would be divided that many times, while the same number of paternal linear divisions at 4 generations would only equal 92.

Yet today, we would never look at 2 people’s DNA, one with 224 crossovers compared to one with 92 crossovers and even consider the possibility that they are both only three generations descended from an ancestor, counting the parents as generation 1.

What Does This Mean?

The number of males and females in a specific line clearly has a direct influence on the number of crossovers experienced, and what we can expect to see as a result in terms of average segment size of inherited segments in a specific number of generations.

Using Granddaughter 1’s maternal crossover rate as an example, in 4 generations, chromosome 1 would have incurred a total of 24 crossovers, so the DNA would be divided into in 25 pieces. At the paternal rate, only 8 crossovers so the DNA would be in 9 pieces.

Chromosome 1 is a total of 267 centimorgans in length, so dividing 267 cM by 25 would mean the average segment would only be 10.68 cM for the maternal transmission, while the average segment divided by 9 would be 29.67 cM in length for the paternal transmission.

Given that the longest matching segment is a portion of the estimated relationship calculation, the difference between a 10.68 cM maternal linear segment match and a 29.67 paternal linear cM segment match is significant.

While I used the highest and lowest maternal and paternal rates of the granddaughters, the average would be 19 and 29, respectively – still a significant difference.

Maternal and Paternal Crossover Average Segment Size

Each person has an autosomal total of 3374 cM on chromosomes 1-22, excluding the X chromosome, that is being compared to other testers. Applying these calculations to all 22 autosomes using the maternal and paternal averages for 4 generations, dividing into the 3374 total we find the following average segment centiMorgan matches:

Crossovers average segment size.png

Keep in mind, of course, that the chart above represents 3 generations in a row of either maternal or paternal crossovers, but even one generation is significant.

The average size segment of a grandparent’s DNA that a child receives from their mother is 80.89 cM where the average segment of a grandparent’s DNA inherited from their father is 1.57 times larger at 126.6 cM.

Keep the maternal versus paternal inheritance path in mind as you evaluate matches to cousins with identified common ancestors, especially if the path is entirely or mostly maternal or paternal.

For unknown matches, just keep in mind that the average that vendors calculate and use to predict relationships, because they can’t and don’t have “inside knowledge” about the inheritance path, may or may not be either accurate or average. They do the best they can do with the information they have at hand.

Back to Philip again who provides us with additional information.

Maternal Versus Paternal Descent

Along a predominantly maternal path the DNA is likely to be inherited in more numerous smaller segments while along a predominantly paternal path it will likely be in fewer but larger segments. So matches who descend paternally from a common ancestor and carry the surname are not likely to carry more DNA from that common male ancestor than someone who descends from a mixed or directly maternal line. In fact, someone descending from an ancestor down an all-male path is more likely to inherit no DNA at all from that ancestor than someone descending down an all-female path. This is because the fewer segments there are the higher the risk is that a person won’t pass on any of them. Of course, there’s also a greater chance that all of the segments could be passed on. Fewer segments leads to more variation in the amount of DNA inherited but not a higher average amount of DNA inherited.

Gammon 3X great-grandparents.png

The chart above shows the spread in the amount of DNA inherited from a 3xgreat-grandparent, down all-maternal, all-paternal and down all possible paths. The average in each case is 3.125% i.e. 1 part in 32 but as expected the all-paternal path shows much more variation. Compared to the all-maternal path, on the all-paternal you are more likely to inherit either less than 2.0% or more than 5.0%. In 50,000 simulations there were 14 instances where a 3xgreat-grandchild did not inherit any DNA down the all-paternal path. There were no cases of zero DNA inherited down the all-maternal path.

One way to think about this is to consider a single chromosome. If at least one crossovers occurs in the meiosis some DNA from each grandparent will be passed down to the grandchild but when it is passed on without recombination, as occurs more frequently in paternal than maternal meiosis, all of the DNA from one grandparent is passed on but none at all from the other. When this happens, there is no bias toward either the grandfather’s or the grandmother’s chromosome being passed on. It’s just as likely that the segment coming down the all-paternal path will be lost entirely as it is that it will be passed on in full.

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