Can 23andMe have it all?

How much do your eyes water when cutting onions? Does fresh cilantro taste like soap to you? Do you have stretch marks on your hips, thighs, or the backs of your arms? Have you ever been diagnosed with brain cancer?

Mail off your spit for a $99 genetic analysis from 23andMe, and you will get information about your ancestry, served up on a web account. You will also encounter a list of optional survey questions. A lot of survey questions. Some are quirky queries about your tastes and habits. Others are intimate probes into your experiences with disease and medicine.

For the team of more than 30 geneticists and statisticians behind one of the world's largest genetic biobanks, the surveys are bread and butter, allowing them to pin down links between DNA markers and people's health, appearance, and bodily idiosyncrasies. New medical and physiological connections have been incorporated into the $99 analysis, adding value for customers. The formula has enabled the Silicon Valley firm to outlast most of its competitors and become a poster child for the fledgling...