I’m sitting in front of a cheerful, candy-colored box that has just arrived in the mail from 23andMe. The instructions inside are straightforward: I need to spit into the test tube provided and send it back to a lab in California for my genome to be sequenced. But as simple as the task is, the enormity of what I’m doing is just dawning on me.

Take, for instance, the fact that I’m about to contribute to one of the largest medical experiments ever conducted, the outcome of which could transform health care. 23andMe gathers millions of DNA samples in its database from customers–80% of whom, like me, share their data for research. The company’s scientists are beginning to deduce some patterns from this information: The company says it has already identified a few insights about Parkinson’s, asthma, and psychiatric disorders, providing some new knowledge to researchers searching for cures.

But 23andMe isn’t just in the business of collecting big data; it is also selling consumers deeply intimate information about themselves and their families. When my report comes back in a month, I will open a Pandora’s box: I will learn about my ancestry, the possible deadly diseases that haven’t yet manifested in my body, and the conditions I might pass on to my unborn children. Sitting alone in my room, untrained in medicine or genetics, will I know what to do if the news is devastating? Am I equipped to handle the anxiety the results might cause me? These thoughts swirl around in my head for several minutes. Then I spit in the tube, reseal the box, and put it in the mail.