Despite recent advances in our understanding of the genetic basis of human behavior, little of this work has penetrated into formal demography. Very few demographers worry about how biological processes might affect voluntary behavior choices that have demographic consequences even though behavioral geneticists have documented genetics effects on variables such as parenting and divorce. Offspring: Human Fertility Behavior in Demographic Perspective brings together leading researchers from a wide variety of disciplines to review the state of research in this emerging field and to identify promising research directions for the future.