Entwined Lives: Twins and What They Tell Us about Human Behavior

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. (Apr.)