What Does “Sharing Genomes” at 23andMe Mean?

underpantsOne of the comments to my posting about 23andMe Producing a 10% Response Rate when contacting matches mentioned that the phrase “share genomes” was really an “overly dramatic, scary and inaccurate phrase.” I never really thought about that before, but that commenter is right. And fear of the unknown is likely frightening some people. Comments since then have conveyed the same concerns. Are people you “share genomes” with going to see you in your genetic underpants???

I’ve condensed another commenter’s statements below:

“I would like to know in advance how much of my info will be available to strangers. The process needs to be better explained to newbies, to reassure us about what is public and what can be kept private, while still participating in the sharing. A bridge is needed between the DNA-for-dummies introductory videos apparently made by the producers of Sesame Street, and the over-our-heads fine detail in the white paper. There’s a wide gap there.”

I agree, and so I’d like to show the basics of what “sharing genomes” means.

Big caveat and disclaimer – I don’t’ work for 23andMe nor do I have any relationship with them other than as a consumer and as a consultant who has recommended their tests in the past generally relative to health and sometimes for ancestry. I have no inside information. This is accurate, to the best of my knowledge, but 23andMe could change their website and/or internal processes at any minute and it might not be accurate anytime in the future. Furthermore, I could have missed something. If so, and if it is brought to my attention, I will update this information.

The titles for each of these sections indicate the various series of clicks you’ll need to do to access the data shown below the title.

When you choose to share your genome with someone, they will be able to see the following information about you, arranged by tab at 23and Me. Note that their tabs for Ancestry information show up in two areas:

My Results, Ancestry Overview 

Sharing genomes 1

Family and Friends, then DNA Relatives and Family Traits

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Several of these are rather frivolous.  Gene Comparison has been obsoleted/removed.  However,  there are a couple that are very important to genealogists.

My Results, Ancestry Overview, Ancestry Tools

Countries of Ancestry

Countries of ancestry shows where you match someone whose 4 grandparents were from the same location.

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23andMe provides the following caveat about your data.

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If you elect to download the data for the person you’ve selected, it looks like this.

sharing genomes 4.1

As you can see, many people remain anonymous. This is a list of the people who match this person selected, and the segments that are listed as entirely Spanish, or UK, for example. This could be useful to you if you find the names of some of your matches, or if you would decide to include this information in your matching spreadsheet. I don’t utilize this information in my spreadsheet, because I don’t feel that grandparents living in one location is terribly useful, although at least one of my matches is utilizing this information. This does not mean that your ancestors or the DNA you inherited in this location (on half of the chromosome in question) is from this location, but it could provide a clue. I can say without a doubt that in the case of some of the Netherlands segments, those did come from my mother’s Dutch lines. Please note that these measurements are in mega-base pairs, NOT in centiMorgans, and will not match up with your spreadsheet segments exactly for that reason.

My Results, Ancestry Overview, Ancestry Tools

Family Inheritance: Advanced (FIA)

This is the primary tool utilized by genealogists.

Utilizing the FIA tool, you can see how up to three different people’s DNA compares against yours. Below, my half-sister’s granddaughter on my father’s side (blue) is compared with my first cousin (once removed) on my mother’s side (green). Of note, they both share with me on some of the same segments, specifically chromosome 5, 7, 11 and 17. That’s not unexpected, because both halves of my chromosomes are showing here, Moms and Dads.

Sharing genomes 5

To see if they actually do match each other, or if their matches are to me on Mom’s and Dad’s side, separately, we check to see if they also match each other.

They do, on one segment, suggesting that they may share a common ancestor that is likely not shared with me. How do we know this? Because their match to each other is on chromosome 19, and their matches in common to me are not on chromosome 19. This means that their matches to me on common chromosomes are simply because one is matching me on Mom’s side and one on Dad’s. Their match to each other on chromosome 19 would need to be investigated separately. As it turns out, I did notice a surname in common in both of their trees, a line that is not shared with me.

Sharing genomes 6

From the above screen, you can’t see segment start and stop numbers, but utilizing the www.dnagedcom.com utility, below, you can download your matches segments to each other by entering your name in the profile (exactly including capital letters) and the person you want to see in the FIA match field. This means you will see all of the matches of your matches to each other. You will NOT see matches for this person outside of those they match in common with you and only for those who are sharing their genomes. You will NOT see anyone who is not sharing genomes.

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My cousin’s downloaded match file looks like this, minus the green shading, and plus full names, which I’ve redacted.

Sharing genomes 8

This is extremely useful because it allows me to see exactly where on the segments that my matches match each other. These are shaded green. This allows me to compare exactly where they match each other, and me. If they match each other, and me, on the same segment, that indicates that we share a common ancestor at that location. So, in this case, my cousin, whose FIA record this is, matches me, William and Diana on a common segment of chromosome 4. She matches me, Sean and Sheila on 5. They don’t have to match exactly, just on some overlapping piece.

Note that this tells us that the segments that I colored green are true matches, as my cousin matches both me and these other individuals at these locations, indicating we share a common ancestor. In some cases, based on genealogy or knowing the person in question, I can tell you exactly from looking at the common matches which lines the people who match come from. This is the goal and the power of chromosome mapping.

My Results, Ancestry Overview, Ancestry Tools

Global Similarity Map

You can see the Global Similarity Map of the people you are sharing genomes with.

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My Results, Ancestry Overview, Ancestry Tools

Neanderthal Ancestry

Your matches can, gasp, see your percentage of Neanderthal ancestry.

Sharing genomes 10

Maternal Line, Paternal Line and DNA Relatives Page

People with whom you share can see your haplogroup on both the maternal and paternal line, page (under the My Results, Ancestry Overview tab,) and they can also see it on the DNA Relatives main match page (under the Family and Friends tab.) Mine is shown below, but if I were a male, it would also include the Y haplogroup. One useful feature on the Maternal and Paternal pages is that you can see your matches sorted by haplogroup which in some cases, especially with a rare haplogroup, maybe a clue as to how you are related, either matrilineally or patrilineally.

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Family and Friends, Family Traits

You can see if you match someone by selecting between traits, such as bitter taste, circadian rhythm, endurance, etc. to see if you share any of the genes for a specific trait such as bitter tasting ability, circadian rhythm, endurance, female fertility, immune system compatibility, non-bitter tasting, pigmentation and weight/body mass index or any set of genes you enter specifically by number.

This shows me compared to my sister’s granddaughter for weight/BMI.

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23andMe Discusses Genome Sharing

What does 23andMe have to say about genome sharing? Here are links

How does genome sharing work? https://customercare.23andme.com/entries/21242872

Learn more and what should I know? https://23andme.zendesk.com/entries/21251933

Family and Friends, Manage Sharing

You can see who you are sharing with. I never share health reports, although I would consider it if someone had a good reason for asking.

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You can manage your sharing by clicking on the green “share your genome” button in the upper right hand corner or by simply accepting a share request.

In Summary

I hope this quick spin-through of “sharing genomes” at 23andMe has been helpful. There is nothing frightening about sharing your genome at 23andMe and if you want to be able to make a sound genealogical connection, it’s necessary. You’re not sharing your entire genome, or your raw data, only selected parts where you match people with whom you are related.

The most frightening part of genetic genealogy is if you discover that you’re related to someone you wish you weren’t, or you’re not related to someone you thought you were. But if you’re playing in the genealogy field, especially the genetic genealogy field, that is a constant consideration and one we’re all aware of.

Happy Ancestor Hunting through genome sharing.

26 thoughts on “What Does “Sharing Genomes” at 23andMe Mean?

  1. Roberta, does the explanation about matching and overlapping chromosomes mean that matches whose chromosomes are exact matches or have overlapping matching segments, share the same set of ancestors (gr…grandparents) or that that may share one or more sets of ancestors (gr…grandparents)? Thanks.

  2. Hi, Great idea explaining often misunderstood term. I just wanted to point out to everyone who may not have noticed that 23andme has greatly improved the default message, so it sounds a bit less scary, in my opinion. It now reads:
    Through our shared DNA, 23andMe has identified us as relatives. Our predicted relationship is 5th Cousin, with a likely range of 3rd to Distant Cousin. Would you like to compare our genomes? By sharing genomes we can compare our DNA using ancestry features and discover clues about how we are related.”
    You can see that they still use the term “sharing genomes”, but they put more of an emphasis on comparing.

  3. P.S. One other comment in regard to your statement about the Countries of Ancestry download: “Please note that these measurements are in mega-base pairs, NOT in centiMorgans, and will not match up with your spreadsheet segments exactly for that reason.”
    This is not accurate. The Ancestry Finder/Countries of Ancestry download has the measurements in BOTH mega-base pairs and centiMorgans. The last column is the cMs.

  4. I think that the default message from 23&Me could still be more reassuring.

    ‘there is no risk involved in sharing your genomes & no one can access your raw data; all it’s for is to see technically how you match & exactly how you compare to others.’

    Having the caveat on there ‘what you should know before your share genomes’ suggests there are real risks involved & put so many off that I no longer ask anyone to share genomes in the first instance.

    • As I’m sure you know, on the health information side of the equation 23andMe has been slapped for being too loose and free with the info. I doubt they’re any mood to ratchet down any of their warnings, as much as I would like that.

  5. the phrase “share genomes” was really an “overly dramatic, scary and inaccurate phrase.”

    A thousand times yes.

    I avoid use of the word “sharing” when talking about matching DNA. “Comparing” is much more accurate and much less frightening. I’ve gotten better response rates at 23andMe and AncestryDNA after abandoning the word “share”.

    23andMe’s use of the word “genome” is also wrong. 23andMe is only looking at a tiny fraction of the genome and most matches only “share” a very small percentage of that.

    Perhaps “compare ancestral DNA fingerprints” or “compare ancestral DNA fragements” would be a better alternative to “compare genomes”.

  6. While we’re talking about sharing genomes, I have a vexing question.

    When I download my Ancestry Finder results, it shows matching segment data for some of my public matches with whom I am NOT sharing genomes. I’m happy to have the extra information, but how and why does this happen?

    • When I’ve seen this before, it’s because someone with whom you are sharing manages different accounts and they authorized all of their accounts to share with you, even though you don’t match all of them. It’s very frustrating for me because one of my people manages more than 20 accounts and I get all of their info even though I don’t want it.

      • In response to this question…

        “So why do people who are not sharing genomes show up in my AF list?”

        …I got this helpful explanation from a customer at 23andMe.

        “The only qualification for appearing in AF, or Countries of Ancestry, is completion of the Where Are You From? or Ancestry Survey.”

        “The only qualification for appearing in DNAR is consent to participate in DNAR.

        “There are users who appear in one and not the other.”

        (For those not familiar with the abbreviations, DNAR = DNA Relatives, AF = Ancestry Finder)

        Another customer added this:

        “I consider the ‘ancestry finder’ file to be a backdoor way of getting most of the shared segment information for quite a few cousins without needing to get the cousins to formally agree to share genome data… partial information is better than no information. I’ll take what I can get.”

      • This is a variation on the problem I commented about yesterday. I have not been able to determine how to share just my info, not that of everyone in my account. The info I’ve found on the 23andme site just tells me to be careful, but I tried to be careful! I cancelled all of my unanswered sharing requests because this issue is a major concern for me.

    • It happens because they are “public matches”. If they fill out the survey, are not close relatives of yours and have chosen the public option, then their matching segments will appear in the CoA/AF download.

  7. Please correct me if I am wrong, but if you view the Advanced Inheritance tool in a table vs a chart, you can see where the segments start and end. I use this feature all the time when exporting information to my Genome Mate database.

    Thank you for your wonderful blog!

  8. I’m in an account with several family members. I had tried to share just for myself, by clicking only my box when I sent the request. Now I’ve just discovered that on accepted requests I’ve ended up with sharing for everyone in my account! Do you know if it is possible to limit sharing such as I thought I was doing?

  9. About how far back does a ‘third to sixth cousin’ go? I feel the trees people provide, going mostly only to 1850 useless. 3rd to 6th cousin is just about all my hits after submitting. And how does one learn to USE the data, not just submit to others ability to ? I can’t gain the same insight for lack of understanding, although being bombarded by others wanting to
    analyze what whatever my saliva might have said about what they could infer?

    • You are in essence looking for people with common ancestors with you. So look for surname matches and follow up with that. First cousins share grandparents, second share great-grandparents, third great-great, and so forth. These are estimates based on how much DNA you share.

  10. Hello. I share 1.27% with 3 segments shared with a lady. I also share .55% with 4 segments shared. Are they close relatives? Their haplogroup show countries they are from. Does that mean my relatives are from there too? I’m adopted so I would love to know. Thanks

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