"What is the book that changed your life? (not novels or religious texts)"
I think it's a wonderful way to connect in a less superficial way and learn a little more about each other. It's also a wonderful way to discover new books worth reading.
This is one of them (the full list is here):
Loaded with case studies which present a unified model of human consciousness—a revolutionary map of the mind that explains our evolution, behavior, personality, and the mind-body connection—this work takes readers on a compelling journey into the mind, human behavior, and future of humankind. This mesmerizing, surreal account of the bizarre adventures of Terence McKenna, his brother Dennis, and a small band of their friends, is a wild ride of exotic experience and scientific inquiry. Exploring the Amazon Basin in search of mythical shamanic hallucinogens, they encounter a host of unusual characters—including a mushroom, a flying saucer, pirate Mantids from outer space, an appearance by James and Nora Joyce in the guise of poultry, and translinguistic matter—and discover the missing link in the development of human consciousness and language.