A spirited account of how hormones influence gender differences and sexual behaviors, along with advice on how to take control of these potent biochemical forces. A physician and sex therapist trained at the Masters and Johnson Institute, Crenshaw (Bedside Manners, 1983, etc.) is one teacher who knows how to make her chemistry lessons painless. She introduces the major players in colorful language: Estrogen is Marilyn Monroe, testosterone is the young Marlon Brando, serotonin is the resident schizophrenic. After a brief look at the sexual stages in the lives of men and women, she examines the role of hormones and other chemicals in shaping romantic feelings and actions. Many chapters open with an attention-grabbing sexual scenario, and numerous other explicit passages are interspersed throughout the text. A dozen or so sex-shaping substances are profiled, with charts providing a summary of each one's characteristics, functions, therapeutic uses, and the factors that raise or lower its level in the body. One of Crenshaw's key messages is that, thanks to the variations in the mix of this chemical brew coursing through their bloodstreams, men and women are different--biologically, sexually, and emotionally. Her other message is that, as human beings, we need not be the slaves of our chemistry. A sizable portion of the book is devoted to menopause and its male version, viropause, which she views as endocrine disorders to be treated by hormone replacement therapy whenever possible. Ever optimistic, Crenshaw concludes with some speculations based on current hormone research with animals. If she's right, there's a brave new world ahead, of longevity and sexual fitness for those who mind their chemistry lessons. Uninhibited, upbeat, and opinionated.