Understanding Sharing at 23andMe

Today’s post explains what “Sharing Genomes” means at 23andMe, describes several points to consider when sharing, and introduces some exciting new developments in sharing at 23andMe.

23andMe has revolutionized how people think about DNA. What used to be hidden inside heavy textbooks can now be the subject of cocktail conversation. It’s not just because our unique Personal Genome Service ® gives people a chance to explore their own DNA — it’s also because 23andMe represents the first genetics-based social network.By “sharing” your genome with other 23andMe customers, you can trace shared ancestry, get a glimpse of the diversity in different people’s genetics, or simply brag about how you’re more Neanderthal than your friends. Through 23andMe you can share a little bit or a lot, or not at all — it’s up to you. What can I share at 23andMe?
Currently, the option without Health reports is called “Basic” sharing on the site, and the option with Health reports is called “Extended” sharing. Within the next two weeks, we plan to relabel these options as follows:
  • “Basic Sharing” will be “Sharing, without health reports”
  • “Extended Sharing” will be “Sharing, with health reports”
We want everyone to understand how sharing works at 23andMe and these new labels more clearly describe the distinction between the two options.
At 23andMe, all customers have the option to share genetic results with others by “Sharing Genomes.”Sharing genomes always allows you to see each other’s results for ancestry features including Maternal and Paternal Lines, Ancestry Painting, and Global Similarity. You can also use the Compare Genes feature to see how genetically similar you are, and the Family Inheritance feature to see which segments of DNA you might share.Optionally, you may also choose to see each other’s results for most Health reports.Currently there is no way to directly view or download each other’s raw genetic data or results for Health reports that require an opt-in. These include BRCA Cancer Mutations (Selected), Parkinson’s Disease, and Alzheimer’s Disease.What should I consider before sharing at 23andMe? The vast majority of things we learn by sharing with others at 23andMe are interesting and positive experiences. For many customers, the ability to compare DNA with friends, close family, and distant cousins is one of the most useful and rewarding aspects of this service. However, there are some aspects of sharing that you should be aware of. Within two weeks, we plan to expand our descriptions of sharing throughout the site to address these aspects more fully.First, some of the information that you directly share can be sensitive, including ancestral origins, family relationships, and health risks. Some people are very comfortable sharing this kind of information, some are not — it’s a personal choice, and the system allows you to be flexible.Second, some features, like Compare Genes and Family Inheritance: Advanced, allow you to compare DNA between two people you’re sharing with. Similarly, your shares may compare your DNA with that of people they’re sharing with. This aspect of sharing allows customers to compare people to each other and opens up new genealogical vistas by allowing customers to find evidence of family relationships. These new-found family relationships can be unexpected and sometimes upsetting, but more often they are exciting pieces of a genealogical puzzle.Third, there is some chance that someone you’re sharing with could learn something about you that you didn’t directly share. For example, if you and someone you’re sharing with have a matching segment of DNA that overlaps a health-associated gene, you might infer something about their genotype on the basis of your own, or vice versa. The one way to be absolutely sure that health information about you is not learned in this way is to abstain from sharing entirely. However, it takes substantial effort to learn things like this.If you’re unsure, we recommend sharing with people you’re comfortable with. Sharing allows you to use more of the features on the website and adds a new dimension to what you can learn about yourself and your family. Many customers share openly with each other and have only benefited from the experience. As you learn more about genetics and develop a finer sense of the issues involved, you might begin to share more openly yourself.New developments in sharing at 23andMe Today we’d like to announce a few exciting sharing-related changes coming to some popular 23andMe Labs. Previously in Family Inheritance: Advanced, you could only run comparisons between your shares and close family members. Now, you’ll be able to compare any two of your shares. In Ancestry Finder, you’ll now be able to view the results for any of your shares.These changes are expected to go into effect within the next two weeks. We are adding this time period to allow customers to absorb and adjust preferences in advance of the changes. If you’re not comfortable with these capabilities, sharing might not be for you. For others, we hope that these changes enhance your experience at 23andMe and speed genealogical research. Sharing and comparing makes your genetics that much more interesting, and we encourage everyone to share at whatever level they wish.If you have questions or concerns you’d prefer not to post, please send them to sharing-feedback@23andme.com.
  • Ruy Cardoso

    You’ve touched on several good points here and pitched this post at a level that I hope people will find informative but not alarming. I note, however, that you do not discuss your current policy of masking certain shared segments within Ancestry Finder, i.e., those segments that are near enough to particular health-related segments such as the ApoE gene (certain variants of which are associated with Alzheimer’s Disease). I share just such a segment with a genetic relative but could not have seen evidence of the shared segment just by using Ancestry Finder since 23andMe deliberately excludes that segment from the Ancestry Finder data and display. This is not necessarily a bad thing, but it should be disclosed to users so that they understand the limitations of the Ancestry Finder tool.

    My own story is this: I was tested on the V2 chip, so I could ordinarily have gleaned no information about which ApoE variant I have. But because my relative was tested on the V3 chip, and because our shared segment covered the ApoE gene, the relative could provide me some probabilistic information about which variant I had if he was willing to look at his own ApoE results and share them with me. He could also have made some probabilistic inferences about which variant I have without my knowledge. As you put it in the post, “if you and someone you’re sharing with have a matching segment of DNA that overlaps a health-associated gene, you might infer something about their genotype on the basis of your own, or vice versa.” That’s exactly what was going on in my case.

    I do disagree with you, however, when you say that “it takes substantial effort to learn things like this.” It doesn’t, unless “substantial effort” refers to the time it takes to learn a little about the relevant genetic locations and how to use FI: Advanced. For casual users, perhaps exerting this effort is unlikely. But it’s not hard.

    I was willing to share genome information with this relative, so the prospect of revealing the health information didn’t particularly bother me, especially since I knew the person long before 23andMe came along. But others might not feel the same way in a similar situation. Certainly I did not anticipate that sharing at the basic level could provide clues to health-related information. I’m glad to see that you’ve made this possibility clearer, though providing an example of how this can work would have been clearer still.

    Will the changes you plan to implement have any effect on the masking of the sensitive shared segments in Ancestry Finder? I can certainly see the argument for continuing the masking, but it would be good to explain how it works so that users will not be befuddled by seemingly invisible segments in Ancestry Finder, as I was for many weeks.

    • Ruy,
      Thanks for your thoughtful comment.

      For those unfamiliar with the feature, Ancestry Finder is a lab at 23andMe, where all the DNA segments from your Relative Finder matches that have told us where they’re from ancestrally are shown in a chromosome display. For example, a segment from someone with full Norwegian ancestry is likely a Norwegian segment, and if you share that segment, there’s a good chance you have some Norwegian ancestry yourself.

      As long as someone is opted in to Relative Finder and has filled out the ancestry survey, their segments can be seen by customers they share DNA with in Ancestry Finder, without respect to whether they’re sharing genomes with that customer. You can only see which customer a given segment belongs to if they have marked themselves “visible to all 23andMe members” in their profile settings.

      We mask loci associated with our opt-in health reports in the Ancestry Finder Lab primarily to limit the chance that “visible” customers may have health-associated genotypes for these reports revealed to them. These loci are masked without respect to whether someone has made their name visible or not. There is no masking in other shared DNA segment-based features, including Relative Finder, Family Inheritance, and Family Inheritance: Advanced tools.

      We appreciate your feedback and will be updating our help sections to clarify how these features work.


  • This is an excellant change and long awaited. Changes like this will reduce the allure of third party sites as well as providing DNA comparisons in a more secure setting that doesn’t require convincing strangers to trust their DNA to you or someone else.


  • R. Walker

    It would be nice to include some graphics. for Instance what they will see on Family Inheritance, Advanced, when Person A shares a segment with Person B.

  • Mary_Ann

    Thank you so much. This will be a tremendous help.

  • Tom Nelson

    I would suggest that 23andMe change their description of the two Levels of sharing, as I have had numerous people who are new to 23andMe request sharing at the Extended Level because they somehow believe that this will provide more information about their family history/genealogy. In other words, they do not at first understand that sharing at the Basic Level is for family history purposes only, and that sharing at the Extended Level add in access to the other person’s medical/health results.

    I have had to explain this difference between the two levels of sharing on numerous occasions, with the very excited people who have just received their results and are not accustomed to the system.

    I NEVER share at the Extended Level, but I do offer to answer specific medical/health questions from those with whom I am actively sharing genome info at the Basic Level.

    For clarification, I would like to suggest that 23andMe replace the term “Basic Level” be replaced with “Family History Level” or “Genealogy Level”.

    Similarly, the Extended Level, for clarification, should be relabeled as the “Medical + Genealogy Level” or the “Medical/Health + Family History Level” or some such variation to make it obvious that sharing at that level involves granting access to medical/health results in addition to sharing for family history/genealogy purposes.

  • T. S.

    I found out a little thing about myself that I would have never known were it not for 23andMe. Turns out my father isn’t who I thought he was. Neither I nor he would have ever realized this if it were not for 23andMe and the relative finder (which did not find him as a relative). This type of news can be very upsetting, but I would rather know the truth about my origins than be blissfully ignorant about it.

    In light of this recent discovery I’ve been changing how I tell my other friends to sign up. I now include a little warning that if their parents are not who they think they are then this will find that out (if their parents participate too).

    Before you sign up for 23andMe and use the tools it provides make sure you are mentally prepared for what you may find out.

  • 23blog

    You select the amount of information that you’d like to share, either broadly or to your matches. For more information on sharing go here: