Ebook: Individual and Environment: Monozygotic Twins Reared Apart

The controversy over the role of nature versus nurture in development continues to this day. More than 100 years ago, Sir Francis Galton initiated the study of twins as a means of elucidating the interaction of heredity and environment. He remarked: "There is no escape from the conclusion that nature prevails enormously over nurture when the differences of nurture do not exceed what is commonly found among persons of the same rank of society and in the same country." This statement has remained a challenge, to be refuted or confirmed by further research.
Identical twins reared apart are very rare. Yet their value for investigations of the origins of both normal and abnormal characteristics is inestimable.
In this book, Dr. Juel-Nielsen reports on a longitudinal study of 12 pairs of monozygotic twins, aged 12 to 77 years, who grew up in different environments in Denmark. After describing the collection and selection of material for investigation, Dr. Juel-Nielsen explains the methods of research, which included extensive interviews, medical examinations, and psychometric assessments. He then presents the results in terms of similarities and differences in general health, intelligence, personality traits, and physical and mental disorders. These results are considered in the light of the differing environmental influences.
Dr. Juel-Nielsen's original study was carried out over the period 1954-1959. This new volume includes for the first time the results of a 20-year follow-up study, completed in 1979. Additional information is provided about the subsequent life course of the twins, their mental and physical health, and the causes of death. As Dr. Peter B. Neubauer writes in his Foreword, this "is a book that deserves to be read many times, for it is a vital resource for all those who study the complex interrelationship between environment and development, between norm and pathology during the life cycle."
- Niels Juel Nielsen, M.D., is Professor of Psychiatry at the University of Odense and Superintendent of the Department of Psychiatry at the Odense University Hospital, Denmark. He has represented the field of psychiatry on the Danish Medical Research Council since 1973.