After chewing a piece of gum, you casually toss it in the garbage and think nothing of it. But what if a few days later, a stranger picks up that piece of gum and sequences your DNA using the trace amount of genetic material from the saliva that you’ve left behind? And what if the stranger then takes the information in your genetic code and reconstructs your likeness? Starting to get uncomfortable? Taking this scenario further, what if you have a genetic predisposition toward a disease or a disorder that you’re unaware of, and suddenly your DNA is in the...