Cashing in on your genes

Spitting is not an activity that has traditionally carried much social cachet. Yet at New York Fashion Week and the Davos World Economic Forum two years ago, an invitation to drool into a tube became one of the hottest tickets around. For Hollywood celebrities and business executives alike, the new place to see and be seen was at a "spit party".

At this 21st-century take on the Tupperware party guests would hand over a little saliva (and a few hundred dollars) to a Silicon Valley start-up called 23andMe. After the cocktails had slipped down the company would extract DNA from the VIP spittle to assess its new customers' chances of developing a hundred or so medical conditions and physical traits, from breast cancer to baldness.

The idea was one whose time seemed to have come. As science started to reveal how genetic influences shape our health, so a new breed of business was taking DNA out of the laboratory and turning it into a glamorous consumer product. Anne Wojcicki and Linda Avey, the telegenic founders of 23andMe, were soon extolling...