Of all the reasons people choose to have their DNA sequenced, the top reason is to learn where they’re from. “Ancestry testing is the most attractive direct-to-consumer product by far,” says Robert C. Green, a medical geneticist and professor at Harvard University who co-authored a study showing 74% of people who use personal genetic testing were “very interested” in ancestry. (Green receives compensation for advising several competitors of Nebula.)

Uploading genetic data into a genealogy website like Ancestry.com requires linking the data people get about their background to identifying information. This is how people are able to find and connect with family members and how police departments have identified culprits of crimes.

Although people may be drawn to genetic testing by an interest in their heritage, they often become interested in the health applications as they learn more, Green says. Nearly as many consumers in his study were interested in understanding their disease risk as they were in learning about their forebears.

Ancestry.com says it does not share users’ information without permission, and medical information is theoretically secure. However, news of data breaches may not reassure people that the data they elect to keep private will remain so.

Many of the people who use direct-to-consumer gene testing also opt in to having their genome included in large databases, often called DNA biobanks. And while this data is usually de-identified, consumers have little faith in the industry’s ability to preserve their anonymity: According to a 2019 public survey on factors influencing a person’s decision to donate DNA and medical information, only 13% of respondents said they trusted company researchers.

“DNA itself is identifiable to individuals. Every hurdle that we can think of putting in place to protect someone’s privacy, there’s probably a way around that hurdle.”

Stories about cross-referencing personal and crime scene DNA databases to identify the Golden State Killer and other criminals have also spotlit the possibility that testing your DNA could implicate relatives. And despite the existence of some legal protections, documented instances of genetic discrimination by insurance companies and schools have caused hesitation in linking identity to genetic information.

In its own market research, Nebula has found privacy to be one of the main concerns deterring people from purchasing genetic tests. “People are beginning to care a lot more about what happens with their data and the services that they use, and they want to have transparency,” says Jake Cacciapaglia, who leads business development at the company. “That still seems to be the highest resonating reason for why [customers] are purchasing us versus other alternatives on the market.”

Nebula offers a higher level of anonymity to consumers by allowing them to pay with cryptocurrency or use post office boxes that obscure their physical addresses.

Additionally, the company’s model for sharing data with other companies hinges on the use of split decryption keys—digital codewords of sorts—one of which is given to the consumer. Much like the way some missiles require two keys turned by two people to launch, Nebula requires both parts of the key to be engaged for consumers’ data to be shared.