From Publishers Weekly
Twin research has fueled bitter debates over the degree of genetic influence on intelligence, disease, mental disorders, special abilities and other traits. Almost encyclopedic in scope, this elegantly written study cogently distills and makes available to the general reader a wealth of research from the fields of behavioral genetics, evolutionary psychology and social science. A professor of developmental psychology and director of the Twins Study Center at California State, Fullerton, Segal contends that studies of twins, raised together or apart, demonstrate that genetic influence affects virtually every human characteristic, including IQ, personality, longevity, sociability, job preference and satisfaction, mathematical skills and athletic prowess. Parents, surprisingly, tend to be highly inaccurate judges of whether their offspring are identical or fraternal twins. Segal endorses testing during pregnancy or routine DNA analysis of newborns, arguing that knowledge of twin type affects parents' and educators' management of twins' behavior. A twin herself, Segal includes helpful chapters on the bonds twins develop, on how to cope with the loss of a twin and on conjoined twins, among other subjects. She also guides readers through new fertility treatments that may increase the odds of conceiving multiples. This survey will capture the imagination of anyone curious about twins or human behavioral development. Photos. Agent, Angela Rinaldi. Copyright 1999 Reed Business Information, Inc.


From Library Journal
In the most significant survey of twin research to date, Segal (director of the Twins Study Ctr. at California State Univ., Fullerton, and a fraternal twin herself) illustrates that by using twins as "living laboratories" we can sort out which aspects of twins' lives are influenced by genetic inheritance, and, in turn, we can begin to "lay bare the basis of human behavior." Drawing on all sorts of twin studies, Segal describes twin types and elaborates on findings regarding the development of personality and intelligence. She also looks closely at twin relationships (including conjoined twins) to understand grief, competition, bonding, cooperation, and more. Most refreshing are Segal's frank discussion of the complications inherent in the research and her many proposals for further research. Though her prose is dense, it holds plenty for anyone interested in twins or in fine questions of human development and evolutionary psychology. This is an excellent supplement to Lawrence Wright's more popularly written Twins: And What They Tell Us About Who We Are (Wiley, 1997). Recommended for academic and public libraries.ARebecca Miller, "Library Journal" Copyright 1999 Reed Business Information, Inc.


From The New England Journal of Medicine, March 23, 2000
The study of twins is a fundamental tool of genetic epidemiology and thus is important to all medical and behavioral sciences. Even in this era of study of the human genome, the definition of phenotypic boundaries in many fields still requires refinement, and genetic and environmental influences require further exploration. Despite their importance, I have heard the results of twin studies described as "opaque" by medical colleagues. They need look no further than Entwined Lives, by Nancy Segal, for clarification. The book covers the various facets of twin research, particularly in the study of behavior, in an accessible and sensible manner. It is ably illustrated with case descriptions and anecdotes of encounters with twins during the author's own work and describes aspects of life as a twin that are not usually included in textbooks, such as grief over the loss of a twin, the special relationship between twins, and legal issues involving twins. Although it focuses on behavior rather than on clinical disorders, the book will be of interest to clinicians because the principles of twin research it explains are widely applicable to an understanding of the human condition. Segal discusses the biologic basis of twinning along with unusual types of "twins," such as unrelated siblings of the same age who are reared together through adoption, and complicated sibling relationships, such as those that can result from modern fertility treatments involving sperm or egg donation or surrogate motherhood. For example, there are twins who had different intrauterine environments because they were carried by different surrogate mothers and, in rare cases, fraternal twins with different fathers. This book deals imaginatively with the ways in which such sibling relationships challenge our notion of twinning and offer new angles for the study of genetic and environmental influences on behavior. Identical twins reared apart offer a rare opportunity to examine similarities between persons who are genetically identical but do not share a common environment; such work is eloquently described and illustrated with fascinating cases. The importance of differences between the members of separated pairs is also highlighted, since these differences tell us as much about environmental influences on behavior as they do about genetic influences. There are interesting chapters on what twin studies can tell us about athleticism, intelligence, personality, and mental disorders, but because the emphasis here is on behavior (as the title of the book suggests), a detailed review of studies of mental disorders in twins is outside its scope. For anyone interested in twin research, this book will provide a wealth of information illustrated with real-life examples and written in an understandable, readable style. Its wide-ranging and up-to-date content makes it a valuable review of all aspects of twin research. Reviewed by Jane Scourfield, M.R.C.Psych.
Copyright © 2000 Massachusetts Medical Society. All rights reserved. The New England Journal of Medicine is a registered trademark of the MMS.


Book News, Inc.
An exploration of behavioral and biological aspects of human twins which discusses both experimental data and anecdotes from twins and their parents. Among the topics treated are twins' language patterns, the biological bases of identical and fraternal twinning, how twin studies affect legal decisions and settlements, and what twin research tells us about athletic skill. -- Copyright © 1999 Book News, Inc., Portland, OR All rights reserved


From Kirkus, April 1999
A comprehensive survey of twin research that includes an impressive array of twin-related data in an anecdote-filled and entertaining presentation. Segal, a twin herslf, directs the Twins Study Center at California State University, Fullerton, and was formerly with the Minnesota Study of Twins Reared Apart (its director, Thomas Bouchard, has written the foreword). Clearly fascinated by her subject, she assumes, probably quite rightly, that interest in twins, especially identical twins, is widespread. Identical twins are, she notes, ``the reflecting pools whose altered images teach us how the range of environmental influences shape developmental outcomes.'' Stories about the remarkable similarities between identical twins reunited after being raised separately are irresistible, and while Segal includes them, she goes far beyond such material. She discusses in detail what twin research has revealed about individuality, identity, and questions of nature-vs.-nurture in intelligence, personality development, and athletic prowess. Segal also considers such topics as pseudo-twins (i.e., same-age unrelated individuals reared together), the special relationship of twins with each other, the effects of one twin's death on the other, how fertility treatments have impacted multiple births, the difference between a clone and an identical twin, and twinning in the animal kingdom. Her interviews with some noteworthy twins, such as the Shapiro brothers, who both became university presidents, are especially revealing. Even the unique problems of conjoined, or Siamese, twins are treated. Its comprehensiveness and its extensive notes make this a valuable source for psychologists and other students of twinning; twins, parents of twins, and anyone who ever wished for a twin will also find much to savor here. (36 b&w photos).


Book Description
"The most significant survey of twin research to date . . . Excellent . . . Recommended."-Library Journal

Twins are nature's living laboratories. Through them we are able to uncover new information concerning the genetic and environmental factors affecting who we are. Studies using identical and fraternal twins hold the keys to understanding our intellectual abilities, personality traits, social attitudes, and behavior. In Entwined Lives, Dr. Nancy Segal brings together cutting-edge information with illustrative case histories of twins and their families. In addition to the fascinating stories of identical twins reared apart and reunited as adults, Dr. Segal provides insights into the unusual language patterns of twins, how twin studies affect legal decisions, the role of fertility treatments in twin and "twinlike" conceptions, and more. This groundbreaking book explores the ways in which twins enhance our knowledge of human behavioral and physical development, while shedding new light on the nature/nurture debate and on the burgeoning field of evolutionary psychology.

"I have been studying twins for nearly thirty years and yet I learned something new and intriguing from every chapter of Entwined Lives."-David Lykken, Ph.D., professor emeritus, Department of Psychology, University of Minnesota


About the Author
Nancy Segal, Ph.D., is a professor of developmental psychology and director of the Twin Studies Center at California State University, Fullerton, and is one of the world's leading researchers on twins. She is a Fellow of the American Psychological Association, was formerly a contributing research editor for Twins magazine, and is a member of the advisory board of the Center for Loss in Multiple Birth and Twins Foundation. She lives in Fullerton, California.

FROM THE PUBLISHER

Twins fascinate us, whether it's their identical looks, their uncannily similar behaviors, or their help in answering the nature versus nurture debate. As public interest in twins and multiple births steadily increases, the amount of in-depth information available on such topics has not kept up. In Entwined Lives, preeminent twins researcher Dr. Nancy Segal provides a groundbreaking study of all aspects of twin life, capturing both the scientific flavor of twin research and the unique experiences associated with development as a twin. This insightful and comprehensive book brings together an array of topics including twins separated at birth, unrelated children reared together at birth (pseudo-twins), the loss of a twin, new fertility treatments and their consequences, twins in sports, twins in the courtroom, even twins in the animal kingdom. Packed with scientific findings and anecdotes, Entwined Lives is a definitive guide for twins, their families, and anyone curious to know more about this phenomenon.

FROM THE CRITICS

- Boston Globe

Thoroughly researched, annotated, and footnoted, Entwined Lives is impressive in the breadth of its study...

Library Journal

In the most significant survey of twin research to date, Segal (director of the Twins Study Ctr. at California State Univ., Fullerton, and a fraternal twin herself) illustrates that by using twins as "living laboratories" we can sort out which aspects of twins' lives are influenced by genetic inheritance, and, in turn, we can begin to "lay bare the basis of human behavior." Drawing on all sorts of twin studies, Segal describes twin types and elaborates on findings regarding the development of personality and intelligence. She also looks closely at twin relationships (including conjoined twins) to understand grief, competition, bonding, cooperation, and more. Most refreshing are Segal's frank discussion of the complications inherent in the research and her many proposals for further research. Though her prose is dense, it holds plenty for anyone interested in twins or in fine questions of human development and evolutionary psychology. This is an excellent supplement to Lawrence Wright's more popularly written Twins: And What They Tell Us About Who We Are (Wiley, 1997). Recommended for academic and public libraries.--Rebecca Miller, "Library Journal" Copyright 1999 Cahners Business Information.

Booknews

An exploration of behavioral and biological aspects of human twins which discusses both experimental data and anecdotes from twins and their parents. Among the topics treated are twins' language patterns, the biological bases of identical and fraternal twinning, how twin studies affect legal decisions and settlements, and what twin research tells us about athletic skill. Annotation c. Book News, Inc., Portland, OR (booknews.com)

Kirkus Reviews

A comprehensive survey of twin research that includes an impressive array of twin-related data in an anecdote-filled and entertaining presentation. Segal, a twin herslf, directs the Twins Study Center at California State University, Fullerton, and was formerly with the Minnesota Study of Twins Reared Apart (its director, Thomas Bouchard, has written the foreword). Clearly fascinated by her subject, she assumes, probably quite rightly, that interest in twins, especially identical twins, is widespread. Identical twins are, she notes, "the reflecting pools whose altered images teach us how the range of environmental influences shape developmental outcomes." Stories about the remarkable similarities between identical twins reunited after being raised separately are irresistible, and while Segal includes them, she goes far beyond such material. She discusses in detail what twin research has revealed about individuality, identity, and questions of nature-vs.-nurture in intelligence, personality development, and athletic prowess. Segal also considers such topics as pseudo-twins (i.e., same-age unrelated individuals reared together), the special relationship of twins with each other, the effects of one twin's death on the other, how fertility treatments have impacted multiple births, the difference between a clone and an identical twin, and twinning in the animal kingdom. Her interviews with some noteworthy twins, such as the Shapiro brothers, who both became university presidents, are especially revealing. Even the unique problems of conjoined, or Siamese, twins are treated. Its comprehensiveness and its extensive notes make this a valuable source for psychologists and other students oftwinning; twins, parents of twins, and anyone who ever wished for a twin will also find much to savor here. (36 b&w photos) .