May 22, 2017 can use your DNA to target ads

With the reduction in costs of genotyping technology, genetic genealogy has become accessible to more people. Various websites such as offer genetic genealogy services. Users of these services are mailed an envelope with a DNA collection kit, in which users deposit their saliva. The users then mail their kits back to the service and their samples are processed. The genealogy company will try to match the user’s DNA against other users in its genealogy and genetic database. As these services become more popular, we need more public discourse about the implications of releasing our genetic information to commercial enterprises.

Given that genetic information can be very sensitive, I found that the privacy policy of Ancestry’s DNA services has some surprising disclosures about how they could use your genetic information.

Here are some excerpts with the worrying parts in bold:

Subject to the restrictions described in this Privacy Statement and applicable law, we may use personal information for any reasonable purpose related to the business, including to communicate with you, to provide you information about Ancestry’s and AncestryDNA’s products and services, to respond to your requests, to update our product offerings, to improve the content and User experience on the AncestryDNA Website, to help you and others discover more about your family, to let you know about offers of interest from AncestryDNA or Ancestry, and to prepare and perform demographic, benchmarking, advertising, marketing, and promotional studies.

To distribute advertisements: AncestryDNA strives to show relevant advertisements. To that end, AncestryDNA may use the information you provide to us, as well as any analyses we perform, aggregated demographic information (such as women between the ages of 45-60), anonymized data compared to data from third parties, or the placement of cookies and other tracking technologies… In these ways, AncestryDNA can display relevant ads on the AncestryDNA Website, third party websites, or elsewhere.

The privacy policy gives Ancestry permission to use its users’ genetic information for advertising purposes. When I inquired with Ancestry, they pointed to the following part of their privacy policy:

We do not provide advertisers with access to individual account information. AncestryDNA does not sell, rent or otherwise distribute the personal information you provide us to these advertisers unless you have given us your consent to do so.

However, it is not clear how your personal information can be used to display “relevant ads” unless either Ancestry operates as an ad network itself or Ancestry communicates some personal information to third party advertisers in order to target the ads. Below, I expand on concerns raised by this privacy policy:

Users may “consent” to the use of their genetic data unknowingly. The privacy policy says Ancestry can distribute users’ private information if Ancestry gets permission first. That permission could be granted by a dialog that users click through without much thought. Research has shown that users are already desensitized to privacy and security warnings.

Even if only Ancestry is using the personal information to target ads, the data might accidentally find its way to third parties. Researchers have demonstrated how it can be difficult to avoid information leakage through URLs or cookies or more sophisticated attacks. If Ancestry categorizes its users according to their genetic traits and then stores and transfers these categories in cookies and URL parameters (a common practice for the analogous “behavioral segment” categories used for many targeted ads), then the genetic data can easily leak to third parties.

The genetic data collected by these services may endanger the privacy of users and their families. A genome is not something easily made unlinkable. Only 33 bits of entropy are necessary to uniquely identify a person. The DNA profiles used by law enforcement in the US today take samples from 13 location on the genome, and have about 54 bits of entropy. The test that Ancestry uses samples 700,000 locations on the genome, which will likely have much more than 33 bits of entropy. In fact, I believe this is enough entropy to compromise not only an individual’s privacy, but also the privacy of family members. With the 13 CODIS locations, law enforcement can already do familial searches for close family members. I hope to touch on the familial aspects of DNA privacy at a later date. The compromise of familial privacy is in part what makes collecting and distributing DNA even more sensitive that just collecting an individual’s full name or address.

Genetic data can be used to discriminate against people on the basis of characteristics they cannot control. More than identity, DNA data may allow someone to infer behavior and health attributes. Major concerns about the impact of genetic information on employment and health insurance led Congress to pass the Genetic Information Nondiscrimination Act, which makes it illegal to use genetics to decide hiring or health insurance pricing. However, GINA may not effectively deter people who 1) are not employers or insurers (e.g., landlords discriminating in their choice of tenants, which is prohibited by California state law but not by the federal provisions in GINA); 2) do not believe they will be caught; or 3) are not aware that they are discriminating, as discussed next.

Unintentional discrimination may occur. The big data report from the White House warns that the “increasing use of algorithms to make eligibility decisions must be carefully monitored for potential discriminatory outcomes for disadvantaged groups, even absent discriminatory intent.” An algorithm that takes genetic information as an input likely will lead to results that differ based on genes. This outcome already discriminates on the basis of genetics, and because genes are correlated with other sensitive attributes, it can also discriminate on the basis of characteristics such as race or health status. The discrimination occurs whether or not the algorithm’s user intended it.

Are genomes "anonymous data"?

Recently researchers showed that an unknown person’s genome (i.e., the genetic information stored in their DNA) can often be linked to their identity. The researchers used the genome plus some publicly available information to link this information. Just as interesting as the result itself is the way that people talked about it. As an example, here’s the opening paragraph of Gina Kolata’s New York Times story:

The genetic data posted online seemed perfectly anonymous — strings of billions of DNA letters from more than 1,000 people. But all it took was some clever sleuthing on the Web for a genetics researcher to identify five people he randomly selected from the study group. Not only that, he found their entire families, even though the relatives had no part in the study — identifying nearly 50 people.

Why would a genome “seem[] perfectly anonymous”? The genome is almost certainly unique to one person. So at the very least, the genome is a pseudonym. But of course the genome is also correlated with all sorts of physical characteristics of the person that are visible. And police use DNA evidence (parts of a genome) to identify people all the time. That’s hardly anonymous.
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