From the New York Times bestselling author and Smithsonian contributor comes a fascinating, in-depth, and provocative exploration of the biology of motherhood and how this ancient maternal instinct has the power to transform us as individuals. Motherhood is the most important developmental stage that adult humans ever undergo. It changes us on a cellular level--our brains expand and grow; our genes turn on and off; our systems of reward and desire are rewired; we even smell and see the world differently. Though a powerful and ancient force, scientists are just beginning to fully understand the maternal instinct and all that it encompasses. It is fragile, malleable, and is an individualized experience. While the maternal instinct is the basic building block of all social interaction, Mom Genes explores how mothers differ from other women and explains the hard science behind our tenderest maternal impulses, showing how hidden forces--from cells to civilizations--shape us as individuals. Groundbreaking, accessible, and with powerful implications for families and entire cultures across the world, this book is vital reading for anyone who has ever wondered what rocks the hand that rocks the cradle.