23andMe Ancestry Composition Examples: Part One

23andMe's latest feature, Ancestry Composition, is finally here!

I am going to examine the Ancestry Composition chromosome paintings and ring charts from a wide variety of 23andMe members so that we can see how Ancestry Composition differs from the old Ancestry Painting, and how the results compare to what people know about their own ancestral background.

PERSON #1
Known Ancestral Background: 4 German great-grandparents, one Welsh great-greandparent, one Native American great-grandparent (probable European admixture), one English great-grandparent, one Scottish/Ashkenazi Jewish great-grandparent

Here is Person 1's original Ancestry Painting.

Person #1 has European ancestry from a variety of countries -- in Ancestry Painting 1 (hereafter referred to as AP1), all of this European ancestry is represented by the plain dark blue. Person 1 also inherited a number of non-European segments from his Native American great-grandparent, which are highlighted in orange. Overall, in AP1 this person gets a 96% European and 4% Asian score.

Here is person #1's new Ancestry Composition.

You can see that his European ancestry is now broken down into subgroups.

• He has one Welsh great-grandparent and one British great-grandparent. Each one of these ancestors contributed an estimated 12.5% of person #1's DNA. He also has a great-grandparent who is part Scottish. Overall, he is approximately 30% British. His "British and Irish" score hits the mark almost perfectly -- 24.2%.

• Person #1 is approximately 50% German. Ancestry Composition picks up on this DNA in several ways. His "French and German" score is 13.7%. Also, his "Eastern European" score is 4.3%. Historically, borders have changed & the German and Polish ethnic groups have interbred quite a bit. This means that Person #1's German ancestors likely had deeper ancestry that could be traced back to Eastern Europe, and this is what is showing up in Person #1's Ancestry Composition.
  
  So, we're up to 13.7% French and German + 4.3% Eastern Europe = 18 of Person #1's total of 50 percent German ancestry is accounted for.
  
  Where is the rest?
  
  Not all of Person #1's German DNA is able to be tagged as uniquely and solely German. For more information about this, please visit this FAQ as well as this excellent guide that 23andMe has published. What we can conclude from this is that much of Person #1's German DNA is unable to be tagged as DNA that is found only in German -- therefore it is under the category of "Nonspecific Northern Europe" and "Nonspecific Europe."

• Person #1 also has a small amount of Ashkenazi admixture. In AP1, this admixture remained undifferentiated from Person #1's European DNA. But Ancestry Composition has tagged it all perfectly. Person #1 gets a score of 2.4% Ashkenazi.

• Ancestry Painting 1 was able to successfully differentiate Person #1's European DNA from his Asian DNA. But Ancestry Composition goes one step further -- it is able to accurately determine that Person #1's Asian DNA is Native American in origin. Before, with AP1, a variety of Asian DNA such as Chinese, Japanese, and Native American were all placed in the same category and unable to be differentiated from one another. But with Ancestry Composition, Person #1's Native American DNA that he inherited from his Native American great-grandparent is correctly tagged as such.

PERSON #2
Known Ancestral Background: 100% Mexican

Once again, we see that Ancestry Composition has done an excellent job at further subdividing this person's DNA into different world subgroups. Previously, Person #2's DNA was categorized into just the three simple categories: Europe, Asia, and Africa. Just by looking at Person #2's AP1, you wouldn't really be able to guess which region of the world she originated from.

Ancestry Composition makes this much clearer. The generic Asian DNA from AP1 is now highlighted as being predominantly Native American in origin. We also see that a significant portion of Person #2's European DNA can be properly categorized as Southern European DNA, much of which can be further tagged as originating from Spain/the Iberian peninsula.

Before, with AP1, we saw generic European DNA plus generic Asian DNA plus a smidge of African DNA. That doesn't say much about this person's origin. But with Ancestry Composition, this person's mestizo heritage -- Native American plus Iberian -- comes through quite clearly.

PERSON #3
Known Ancestral Background: half Bulgarian and half Turkish

It's a very similar story with person #3. His AP1 is quite similar to person 1's, so it's reasonable to suppose that, like person #1, he also has primarily European ancestry with a distant Native American ancestor. Just by using AP1, there's no way of proving or disproving this hypothesis.

Ancestry Composition comes through and delivers a strikingly different picture, though.

• This person has a mix of Bulgarian and Turkish ancestry, and accordingly, Ancestry Composition clearly tags much of this person's European DNA as being Southern/Eastern European, with the lion's share tagged as originating in the Balkan peninsula.
  
  
• Person #3's Arab portion is correctly differentiated as Middle Eastern, and reflect's person #3's Turkish ancestry

PERSON #4
Known Ancestral Background: 7/8 Irish, 1/8 Scottish

•  Person #4's original Ancestry Painting lists her as being 100% European. This is perfectly consistent with what Person #4 knows about her ancestry, but is quite generic
  
  
• Ancestry Composition zooms in a bit deeper and is able to readily identify all of the British Isles heritage that person #4 has. Her ancestral background is 100% British and Irish, and her Ancestry Composition score is 86.1% "British and Irish." The leftover portion is largely tucked into the "nonspecific Northern Europe" category, meaning that some of her British/Irish DNA is not specific to the British Isles, but is instead found throughout Northern Europe.
  
• There are a couple of tiny segments showing a very small amount of North African ancestry. This could be statistical noise or it could be indicative of a trace amount of DNA from a historical migration pattern.

PERSON #5

Known Ancestral Background: African-American

 

One thing I want to highlight in this person's painting that I haven't previously discussed is the power of phasing. Phasing means separating your maternal complement of chromosomes from your paternal complement of chromosomes. Ancestry Painting #1 was entirely unphased, but Ancestry Composition contains a step in which the genome is phased (for more info, read here).

Separating the paternal side of your genome out from your maternal side gives you a clearer picture of what you are looking at in terms of your ancestry.

Here's an example, with AP1 on top and AP2 on the bottom. In AP1, it's a zigzag mess with tiny Asian, African and European chunks interspersed with one another. This is because the data is unphased. Phasing smooths it out dramatically and we can now see, for example, that this person inherited a large piece of African DNA from one parent on chromosome 5 and Native American DNA from the other parent. It's separated out rather than hodgepodged together like it was with AP1. This can potentially be a great help when used in combination with Family-Inheritance and Relative Finder -- phased chromosome painting may show more clearly what region a shared segment likely comes from.

That's all for now!

Check back soon for my upcoming posts, which will focus on the Ancestry Composition of these individuals: 

• Person #6: Known Ancestral Background: three quarters German and one quarter Norwegian
• Person #7: Known Ancestral Background: Iranian
• Person #8: Known Ancestral Background: one quarter Swedish, one quarter German (with possible Polish admixture), one half Polynesian
• Person #9: Known Ancestral Background: half Italian, 3/8 Portuguese, 1/8 Danish
• Person #10: Known Ancestral Background: Somali and Ethiopian
• Person #11: Known Ancestral Background: Brazilian
• Person #12: Known Ancestral Background: half African-American, one quarter Icelandic, one quarter Hungarian Jewish
• Person #13: Known Ancestral Background: English, Scottish, German, Ashkenazi Jewish
• Person #14: Known Ancestral Background: half Burmese, half Indian (Tamil)
• Person #15: Known Ancestral Background: Italian, with some Italian Jewish ancestors as well
• Person #16: Known Ancestral Background: one parent African-American, one parent Caucasian
• Person #17: Known Ancestral Background: Colonial American (with most ancestry coming from the Southern states South Carolina, North Carolina, Tennessee, Virginia, and Georgia)
• Person #18: Known Ancestral Background: Mennonite ancestry
• Person #19: Known Ancestral Background: half Dutch, roughly 3/8 Portuguese, and 1/8 African
• Person #20: Known Ancestral Background: n/a, adoptee
• Person #21: Known Ancestral Background: half African-American, half Ethiopian
• Person #22: Known Ancestral Background: Lebanese/Turkish/Assyrian
• Person #23: Known Ancestral Background: half Indian, half Italian
• Person #24: Known Ancestral Background: 7/8 colonial American, 1/8 Polynesian
• Person #25: Known Ancestral Background: colonial American
• Person #26: Known Ancestral Background: colonial American
• Person #27: Known Ancestral Background: at least one quarter Chinese, at least one quarter Jamaican, some English, Irish, German, and African ancestors
• Person #28: Known Ancestral Background: n/a, adoptee
• Person #29: Known Ancestral Background: Saudi Arabia and Kuwait
• Person #30: Known Ancestral Background: 100% Chinese
• Person #31: Known Ancestral Background:  three Caucasian (primarily Swedish and Irish) great-grandparents, five African-American great-grandparents
  Person #32: Known Ancestral Background: half colonial American, half mixed European (mom is 1/8 English, 3/8 Irish, 3/16 Scottish, 1/4 German, 1/16 Ashkenazi)
• Person #33: Known Ancestral Background: half Russian, half German
• Person #34: Known Ancestral Background: Predominantly French with some Spanish and Italian admixture
• Person #35: Known Ancestral Background: Spanish, Jewish, Mexican, French, Italian, and Portuguese
• Person #36: Known Ancestral Background: Predominantly of Mexican ancestry, with Native American, German, and colonial American ancestors as well
• Person #37: Known Ancestral Background: half Romanian Jewish, half Hungarian
• Person #38: Known Ancestral Background: 100% Italian
• Person #39: Known Ancestral Background: 100% Finnish
• Person #40: Known Ancestral Background: half Irish, half colonial American
• Person #41: Known Ancestral Background: Polynesian and Caucasian (English and German)
• Person #42: Known Ancestral Background: 3/8 Irish, 1/8 Scottish, about 1/4 colonial American, about 1/4 French Canadian
• Person #43: Known Ancestral Background: half Russian, other parent unknown
• Person #44: Known Ancestral Background: African American (with ancestors from South Carolina, North Carolina, and Puerto Rico)
• Person #45: Known Ancestral Background: Italian and Polish Jewish ancestors
• Person #46: Known Ancestral Background: half Dutch, also African, Italian, Spanish, and distant Native American ancestors
• Person #47: Known Ancestral Background: half Norwegian, half colonial American
• Person #48: Known Ancestral Background: n/a, adoptee
• Person #49: Known Ancestral Background: 100% German
• Person #50: Known Ancestral Background: Ashkenazi Jewish
• Person #51: Known Ancestral Background: half Colombian, half Italian
• Person #52: Known Ancestral Background: French and Belgian
• Person #53: Known Ancestral Background: 100% Turkish
• Person #54: Known Ancestral Background: 100% Greek
• Person #55: Known Ancestral Background: at least half Mennonite, other parent is colonial/Mennonite mix
• Person #56: Known Ancestral Background: one quarter Indian, one quarter Burmese, one half colonial American
• Person #57: Known Ancestral Background: n/a, adoptee
• Person #58: Known Ancestral Background: colonial American
• Person #59: Known Ancestral Background: colonial American
• Person #60: Known Ancestral Background:  n/a, adoptee

Utilizing Your Relatives on 23andMe -- Relative Finder

Getting your close family members tested is immensely useful when trying to sort out your Relative Finder matches. Close relatives share some of your DNA, and they will also share some of your relatives.

It’s very straightforward when a family member shares the same relative in common as you do, like this.

In this case, my paternal first cousin shares the same segment with the same relative as I do. This provides clear evidence that this relative is related to me on my paternal side.

However, sometimes you can make a conclusion about which side a relative comes from even when a family member does not share the relative.

Let's say I want to try to figure out which side of my family this relative is on. Although I have lots of relatives tested, to keep things simple, I am going to pretend that the only person I have available to use is my paternal half-sister Kim.

The first step is to take note of the segment's location. This segment is on chromosome 2, and has a start point of 140.000.000 and an end point of 151.000.000.

The next step is to take a look at how I match my half-sister at that spot on chromosome 2 (this info is found using the 'View in a Table' feature in Family Inheritance: Advanced).
I need to check and see if Kim and I share DNA at the same spot as my 5th cousin and I do. And we do -- Kim and I have a shared segment that goes from position 129.000.000 to 181.000.000, which definitely encapsulates the segment that I share with my 5th cousin (140.000.000-151.000.000). This means that I can make a conclusion about which side of my family this match comes from. (Please note that if Kim and I did not share a segment at the same spot that I match my relative, no conclusion could be made).

I know that I have two copies of chromosome two, one from my mom, and one from my dad. Kim and I got the same chunk of DNA on chromosome 2 from my dad (I know this because Kim and I are related only through my dad and not my mom). Therefore, if Kim also shares this match with me, this relative is on my dad's side. This is not the case -- Kim does not share this relative with me. Therefore I know this relative is not on my dad's copy of chromosome 2. The only other possibility is that this relative is on my mom's copy of chromosome two, and therefore I know that this relative is related to me on my mom's side.

You can sort out which parent your Relative Finder match came from by using collateral relatives that are related to one of your parents but not the other. Close relatives in this category include half-siblings, aunts and uncles, and first cousins. Siblings do not work for this because they are related to both of your parents and all four of your grandparents, just like you are. Therefore any shared DNA and shared relatives that you have with your sibling could have originated with either parent.

You can sort out which grandparent your Relative Finder match came from by using collateral relatives that are related to only one of your grandparents. Close relatives in this category include half first cousins or first cousins once removed, second cousins, great-aunts and great-uncles, and a variety of other relatives.

If you have a more distant relative tested, like a first cousin twice removed or something like that, it's possible to narrow down which great-grandparent a match comes from, and so on.

Also, if you have direct ancestors tested, the process is very similar to what I outlined above and in fact in some cases it's a little simpler. If you've got one of your parents tested, let's say your mom, and your Relative Finder match does not match your mom, you can reasonably conclude that the relative is on your dad's side. If you have a grandparent tested, and the Relative Finder match is not shared with your grandparent, you would follow the same checking-the-segments procedure that I outlined with Kim.

This method isn't perfect -- it's possible to have a 'false positive' match -- this means that your Relative Finder match does not match either one of your parents. It's also possible that a testing error, such as a miscall, will prevent a legitimate relative from properly showing a shared segment. But for the most part, comparing the segments like I outlined above should work for you. The larger the segment, the more accurate using this method is.

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You can also use the knowledge that you get ONE chromosome from mom and ONE chromosome from dad to your advantage when trying to sort out your relatives. What this means is that at any given spot in the genome, you share DNA with one and only one of your maternal ancestors and one and only one of your paternal ancestors.

I will use my pedigree as an example:

If I share DNA with, let's say, my grandfather Ernest Badger, at a certain spot in the genome, I know for sure that I do not share DNA with my grandmother Audra Woodward at that same spot.

Graphically illustrated, this is what it looks like. At any given location, you can share DNA with one paternal grandparent or the other, but not both. You can share DNA with one maternal grandparent or the other, but not both.

Let's take a look at an example Relative Finder match. Andrea, Kim, Kelly, and Hailey are the four daughters of my dad. Aletha is our paternal aunt and Leona is our paternal first cousin once removed. Using the tools I've outlined above, let's see what we can find out regarding the side of our family that these relatives come from.

I told you earlier that aunts can sort out which parent a match comes from, and first cousins once removed can sort out which grandparent. So we know that our match 'Jack' comes from our dad's side, and our match 'David' comes from our paternal grandfather's side (because Leona is related only to our paternal grandfather, and not our paternal grandmother).

We don't have to stop here, though. By using the 'ONE piece of DNA = ONE ancestor' rule and by visualizing the chromosomes, we can make another conclusion -- we can decide which grandparent our match Jack comes from.

Here's a sketch of my dad's chromosome 17 at the relevant spot.

Now let's look back at our Relative Finder matches. Andrea, Kim, and Kelly all have the same relative and therefore the same piece of DNA. Hailey has the same relative and therefore the same chunk of DNA as our paternal first cousin once removed, and this cousin is related only to our paternal grandfather, my dad's dad. Therefore, Hailey got the 'blue' piece of DNA.

So here's what we have so far.

Let's think about this for a minute. We know several things.

1. Every child inherited a piece of that DNA from dad.

2. Andrea, Kim, and Kelly inherited one piece, and Hailey inherited the other piece.

3. Hailey inherited the blue piece.

This leads us to our conclusion -- Andrea, Kim, and Kelly inherited the 'green' piece of DNA, the piece from my dad's mom (our paternal grandmother). We can now conclude that our Relative Finder match 'Jack' is related to us on our paternal grandmother's side.

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I hope this mini-tutorial was not too hard to understand! The number of Relative Finder matches you are able to sort and the types of conclusions you are able to make will vary depending on which family members you have tested on 23andMe. If you have any questions, need any clarification, or want me to look at a specific situation in your family, please leave a comment or email me at

My Close Relatives on 23andMe: Paternal Second Cousin Once Removed

I recently got results for my dad’s second cousin.

Here is how Ron matches with his second cousins -- nothing unusual here. Second cousins are expected to share about 3.125% of their DNA, and everyone shares approximately this amount with Ron.

Things start to get weird when looking at the comparisons between Ron and my three sisters and I. We are second cousins 1x removed, and would be expected to share about 1.5% of our DNA.

One of my sisters has a fairly normal match to Ron, although her percentage is slightly above average. Surprisingly, she passed on every single segment perfectly intact to one of her daughters. Her other daughter got most of the segments -- she shares about 70% of the DNA Ron shares with her mother compared to the expected 50%.

My dad's other three children have only a very small match to Ron. We share about three or four times less DNA than expected. These results are more consistent with a fourth cousin as opposed to a second cousin 1x removed.

After looking at this comparison, it might be tempting to conclude that because we have such a small match compared to the average percentage for second cousins 1x removed, our dad probably had a smaller than average match too.

However, there is no evidence to suggest this.

If you add up all the unique segments that my dad’s four daughters inherited from him, it’s 13 + 43 + 38 + 29.5 + 18.5 + 44 = 186 cM = at least 2.48% of DNA shared between my dad and Ron (there’s also a decent chance that Ron and my dad shared segments that none of his daughters happened to inherit). This percentage is slightly below average for second cousins (2.48% compared to 3.125%), but not dramatically low.

However I only received 26 out of 186 cMs, or about 14% of Ron’s shared DNA compared to the expected 50%. My sister inherited a piddly 13cM out of 186cM, or about 7% of the shared DNA. Sister #3 inherited 30 cM out of 186 (16% of the shared DNA). Sister #4 seems to be skewed in the other direction -- she inherited 157cM out of 186cM (84% of the shared DNA).

Can I coin a ‘new’ saying?

“Recombination is like a box of chocolates, you never know what ya gonna get!”

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Jason Woodward and Dorotha Drew Woodward, our common ancestors.
Thanks for the DNA!

Questions from my Inbox: Siblings

I was looking at my site’s traffic, and I notice that an awful lot of people find my website by googling questions about the DNA shared between siblings.

I thought it might be useful to answer some of these questions and clear a few things up.

“What percent of my DNA is the same as my sister’s?”
“How much of my DNA is shared with a sibling?”
“How much DNA should brothers and sisters share?"

The short answer is that siblings share an average of 50% of their DNA.

Here’s why siblings share 50% of their DNA.

Your mom has two copies of every piece of DNA and your dad also has two copies. To make a child, each parent passes on one copy of their DNA – consequentially, the child will also have two copies of that piece of DNA.

I have drawn an example below.

Let’s say that on this particular piece of DNA, you are outcome #3 – ‘green and purple’. You got a ‘green’ copy of DNA from your mom and a ‘purple’ copy from your dad.

Your parents can produce a child with any one of the four combinations that I drew. Take a look at how the four possible outcomes compare to your outcome (green and purple).

There is a one out of four chance (25%) that a new child of your parents would have an identical match as you (that is to say, they would also get a green gene from mom and a purple gene from dad).

There is a two out of four chance that the new child would be only half-identical to you. If the child was outcome #1, they would have an identical gene from your dad (purple) but a different gene from your mom (red instead of green like you). Outcome #4 is the same except reversed. Your sibling would have an identical gene from your mom (green) but a different gene from your dad (blue instead of purple).

There is a one out of four chance that the sibling would inherit a different copy of both genes. This is what happens with outcome #2. This sibling got a red copy of your mom’s DNA, while you got a green copy. He also got a blue copy of your dad’s DNA, while you got a purple copy instead.

To summarize, at any given point in the genome, there is one way to be fully identical with your sibling, two ways to be half-identical, and one way to be non-identical.

Said another way, across the entire genome, you will share about ¼ of your DNA fully identical with your sibling. You will share about ½ of your DNA half-identical with your sibling, and about ¼ of your DNA will be non-identical compared to your sibling.

25% identical DNA (100% match – same from mom AND dad) = .25 * 100 = 25%

50% half-identical DNA (50% match – same from mom OR dad but not both) = .50 * 50 = 25%

25% not identical DNA (0% match – different from both mom and dad) = .25 * 0 = 0%

25% + 25% + 0% = 50%. Siblings share an average of 50% of their DNA.

Okay, I’ll rephrase this: “Why do I only share 45% with my sister?”

50% is only an average percentage. This percentage can and does vary quite a bit. On the thread that I started on 23andMe about shared DNA percentages with relatives (23andMe members can read that thread here) the highest reported sibling percentage was 58.27% and the lowest was 40.99%. Sharing 45% with a sibling is lower than average, but it's nothing unusual. 
"Will my siblings get the same 23andMe results?"

Not really.

Some aspects of your 23andMe results will be the same – for example, your maternal and paternal haplogroups.

Most of your results will not be the same as your sibling’s results, because, like we discussed earlier, you and your sibling each get a unique combination of DNA from your parents. Your health results will most likely be somewhat similar, but they will not be identical. Same with Relative Finder – your results will be similar. Because you share ~50% of your DNA with a sibling, you will share roughly half of your relatives in common with your sibling (but around half will be different for each person).

 
"Can one sibling have a closer DNA match to the parents than the other one?"

Sort of. It depends on what you mean by 'closer DNA match'. Every child gets a complement of 23 chromosomes from each parent -- this does not vary. However, a father passes along a Y sex chromosome to a son, and an X sex chromosome to a daughter. In terms of size, the X chromosome (left) is a lot bigger than the Y chromosome (right). You could say, based on this size difference, that a father gives more DNA to his daughter compared to his son, and that therefore a daughter has a closer match to her father than her brother does. Some companies, such as 23andMe, will report that a man shares ~47% of DNA with his son and ~50% with his daughter. So in this respect, you could say that one sibling has a closer DNA match to the parent than the other sibling does.

However, something to keep in mind is that the parent-child relationship does not vary like other relationships do. For example, we already talked about the wide range of percentages that siblings can share (on my thread, they share anywhere from about 41% to 58%). Parents and children do not vary like this -- it's always 50% from mom, 50% from dad.

"Can DNA test if you are full sisters without the parents?""Can sisters determine if they are true sisters through DNA testing, even if both parents are dead?"

Yes, definitely.

Sibling relationships are very unambiguous, with or without the parents.

On 23andMe, sibling comparisons look like this. The percentage of DNA shared is approximately 50% and there are both fully-identical segments and half-identical segments (as well as some non-identical segments). No parents are needed to identify a sibling relationship on 23andMe.

For what it's worth, here's what a half-sibling comparison looks like.

For the most part, half-siblings share only half-identical segments -- no fully-identical segments. (An exception to this rule would be seen with maternal half-brothers on the X chromosome. Men have only one X chromosome, so any match between two men on the X would show as fully-identical.)

Also, here's what a comparison between two unrelated people looks like.
It's blank, with no shared segments.

You can see that these various outcomes are very distinctive from one another. 23andMe can definitively determine whether two people are full siblings or not.

I hope this helps answer some of your questions about siblings and their shared DNA! If you've got a question for me, leave a comment or email me at:

Utilizing Your Relatives on 23andMe -- Health Info

Have you ever been curious about which side of the family a particular trait comes from? Ever wondered what traits you and your relatives share in common?

Your 23andMe info can help you find the answers to these sorts of questions.

I will show you how this is done. The first thing you will want to do is download my spreadsheet -- it can be found here. It contains all the info about the location in the genome of the traits and conditions that 23andMe tests for.

The first half of the spreadsheet is in alphabetical order, so that you can quickly find a certain condition that you may be interested in. The second half of the spreadsheet (starting at row 630) is in order by location, so that you can see which traits and conditions fall along a particular segment that you are interested in. After going to the link, you can download the file and save it as you wish so that you can manipulate it to your own preferences.

So how can you use this information?

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Let's say you are curious about which side of the family you might have inherited a certain gene from. As an example, I'll choose APOE, the gene that 23andMe tests for regarding Alzheimer's disease.

My niece Mikayla and her great-grandmother Pearl have both been tested on 23andMe. As you can see, they both have an APOE3 allele -- the question I want to answer is, 'Did Mikayla inherit that APOE3 allele from Pearl?'

(all of the images in this post can be enlarged by clicking on them)

The first thing that I need to do is check the spreadsheet, so that I know where the APOE gene is located.

The gene is on chromosome 19, at approximately location 50,000,000.

The next thing I need to know is whether Mikayla shares a segment at that location with Pearl, her maternal great-grandmother. There are several places I can go to find this information -- Family Inheritance or Family Inheritance: Advanced. I'll choose Family Inheritance because it has a feature that allows you to check for a specific gene -- I can enter APOE in here and see what the exact segment looks like:

This comparison shows that Mikayla and Pearl DO share a segment at the location where the APOE gene is. This means that Mikayla DID inherit her APOE3 allele from her maternal great-grandmother Pearl (we can also conclude that she inherited her other APOE allele, the APOE2 allele, from her father).

I should add that this technique is most useful when you do not have the exact same genotype as your relative. For example, here's what my paternal first cousin and I have for the eye color gene:

We do share a segment at the location where the eye color gene is. But, no real conclusion can be made -- all this tells me is that I inherited either an A or a G at this gene from my dad, which I already knew (everyone gets one allele from their mom and one from their dad).

Your mileage may vary, depending on what question you are asking and what relatives you have available for comparisons, but in general, it's best to use a relative that you only have one allele in common with (for example, in my Alzheimer's example, Mikayla is APOE2/APOE3 and Pearl is APOE3/APOE4. They only have the APOE3 allele in common).

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Let's say you want to take a different approach -- rather than having one specific trait in mind that you want to look at, you want to know which traits or conditions fall along a particular segment that you share with your family member.

First, you need to know which segments of DNA you and your relative share. Here is my comparison with my paternal half-sister. I'll choose chromosome two as an easy example to look at, because my half-sister and I happen to share the full length of our dad's chromosome two with one another.

The next step is to go to the spreadsheet and look and see what traits are shared at this location.

For all of these genes, we inherited the same allele (same version of the gene) from our dad. So what does this tell us? Let's look at one of these traits -- I'll choose lactose intolerance.

Let's take a look at what we see. I am AG at this gene, meaning I have one 'lactose tolerant' allele and one 'lactose intolerant' allele. My half-sister is AA, meaning that she has two 'lactose tolerant' alleles. Because I know we inherited the same allele from our dad, and we have only one allele in common, I know that we inherited our A allele from our dad. Hopefully my reasoning is clear.

I can make several conclusions based on this data. One I already mentioned -- my sister and I inherited an 'A' lactose tolerant allele from our dad. Also, because it takes only one lactose tolerant allele to be lactose tolerant, I know that my dad was lactose tolerant.

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I'll go through one more example, this time with a more distant relative -- my aunt's second cousin.

Here is my aunt's comparison with her second cousin.

I highlighted the segment I want to focus on -- the shared segment at the end of chromosome nine. I want to find out which traits or conditions they share from this segment.

So my next step is to go to the spreadsheet:

Here is a list of traits that they inherited from that chromosome 9 segment. I'll choose blood type as the trait I want to focus on. Let's take a closer look at what their genotypes are for ABO blood type.

So what does this mean? The fact that they have a shared segment at the ABO blood type gene means that at that gene, they inherited a common allele from their common ancestors. They have only one allele in common -- the A allele.

Here's their family tree:

From the DNA evidence, we know that Jason and Dorotha Woodward had at least one A allele between them. One of them (no way to tell whether it was Jason or Dorotha) passed this same A allele to each son, William and Hermon Woodward. William passed the A allele to his son Bruce, who also passed it on to his son. Bruce's son has two A alleles -- he got one from Bruce and one from his mother.

In turn, Hermon passed on his A allele to his daughter Audra Woodward, who then passed it onto Aletha. We can conclude that Aletha got her A allele from her mother and her O allele from her father.

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So, to summarize:

The first step is to decide what question you want to ask.

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If you have a specific trait in mind (like with the Alzheimer's example) and you want to know which side of the family you inherited a certain allele from, here's what you want to do:

Step One: Go to the spreadsheet and figure out the relevant information. You need to find out where (which chromosome and what position) that trait is located.

Step Two: Go back to 23andMe and see if you've got a relative that will help you. Most likely, you are going to want a relative that (1) has a different genotype than you -- only one allele in common, (2) shares a segment with you at the relevant location and (3) is related to you on only one side of your family.

Step Three: If you have a relative that fits the criteria (also, keep in mind that the criteria will vary based on what type of questions you are asking) -- you can make a conclusion about the trait you selected.

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On the other hand, if you don't have a specific trait in mind, but you want to look at a specific shared segment and then go from there to figure out which traits were inherited via that segment (like with the second cousin blood type example), here's what you want to do:

Step One: Go to the spreadsheet and figure out the relevant information.  You will probably want to go to the bottom half of the spreadsheet and find the segment, so that you can see what traits fall along that segment.

Step Two: Take a look at the genotypes of you and your relative for those traits. Due to the fact that you have a shared segment with your relative, you know that you and your relative must have at least one allele in common from your shared ancestor for all the relevant traits. The exact conclusions you can make will vary based on your relationship with your relative.

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I think that about covers it!

If you have a question or want me to investigate a specific scenario in your family, please comment on this post or drop me an email at:

Also, if you're going to write about this on your own website, I would love a link back to my website! Thank you!