Siddhartha Mukherjee’s Pulitzer Prize-winning first book on cancer, The Emperor of All Maladies, was a medical book, a literary work and a thriller all rolled into one. Just when it seemed it would be tough to surpass, the top oncologist has come up with another stunner, this time on The Gene. The book traces the history of genetics in a manner only Mukherjee can achieve, and raises many disturbing questions about the future of the human race. Would humans soon be not like as we know them? Mukherjee answers this and other questions in a telephonic conversation from Massachusetts with Satish Padmanabhan. Exerpts: