We charged one worrywart writer, Michael Rosenwald, with getting as many different DNA tests as he could to find out what his future--or, more specifically, his genes--had in store for him. In a search for everything from cancer to narcolepsy, Rosenwald sent blood samples or cheek swabs to genetic-testing labs across the country. The DNA in the harvested cells was then extracted from the cells' nuclei to undergo PCR amplification, essentially molecular photocopying. Once sufficient copies (at least one million, sometimes up to a billion) of the required DNA had been made, a variety of techniques were used to detect genetic variations. Here's a rundown of the tests he took and how each test works.