James Watson, co-discoverer of the structure of DNA, did it. So did Craig Venter, co-mapper of the human genome. Now you, too, can map your entire genome and reveal some of its many secrets — for just $399 and a little spit. Scientists debate whether that information is really worth anything at the moment — in many cases, there isn't enough scientific knowledge to interpret what it really means to have this gene variant or that one — but companies like 23 and Me at least make it possible for you to take a gander at your genetic data. (Although the service was available previously, until this year, it's been prohibitively expensive.) You provide a sample of saliva, from which your DNA is extracted, copied and combed for the presence of 90 known genetic variations that code for different traits or conditions, from lactose intolerance (though you could probably drink a glass of milk and find out for far cheaper) to prostate cancer. Right now, there's no way to know whether you'll get cancer just because you have the gene, but once the science has advanced, the hope is that such genetic mining will predict disease, giving people the option of seeking treatment before they get sick.