When Drew Endy envisions the future, he sees giant gourds engineered to grow into four-bedroom, two-bathroom houses. He sees people alerted to nascent tumors in their bodies by internal biological sensors, and cars fueled by bacteria-produced gasoline. Endy, 37, is a pioneer in synthetic biology, a field that combines biology, chemistry, and engineering to remake biological systems to act according to human design. In other words, he’s a little like God, if God were a geek.