For sheer ability to convey without sentimentality the plight of families who learn that they harbor a lethal gene which threatens or even now is killing a child, Stockton is masterful. A veteran AP reporter, he is informed, compassionate, subtle, and sensitive as he describes the effects of truly bad news on such families. These are the people whose destinies are permanently altered (hence the title) by the pediatrician who says your daughter has Tay-Sachs disease, or there is reason to believe that your adoptive child may develop myotonic dystrophy. Tracing a dozen or so case histories, Stockton reveals the infinite variety of human suffering and strength, at the same time providing a primer in modern genetics, cytogenetics (chromosomal research), fetal research, and genetic counseling. The reader, caught up in the drama, shares the suspense of the woman waiting to hear the results of a new experimental fetal blood test for muscular dystrophy (since disproven) and anxiously endures the final weeks of pregnancy of an Rh negative mother whose unborn child must receive repeated blood transfusions. Stockton lets these people speak, and often the recall is bitter--of the doctor who said ""Lightning never strikes twice. . ."" or the one who, having rendered the verdict, simply abandoned the case. Stockton is emphatic on the need for sensitive genetic counseling at precisely this time and in the months that follow. The shock is so great, friends and relatives frequently so obtuse, denying, or pollyanna-like, that couples turn in on each other with a pressure that as often breaks as makes the marriage. Many well-known researchers and clinicians are involved in the stories, but the families have been given fictitious names--except for the exceptional born-again gospel-singing Halls, the family riddled with cancer. An absorbing presentation of human beings in all their frailty and courage.