Not All Twins are Alike: Psychological Profiles of Twinship

Twin Research Volume 6 Number 4 p. 351 Given that Barbara Schave Klein is a clinical psychologist, it should be no surprise that this book, her sixth, has an analytical focus. The book stems from her research interest in the psychodynamics of twinship, but her personal experience of identical twinship is declared from the beginning and sets an intense tone that pervades the book. Dr Klein’s twin sister, Marjorie Ford, writes the Foreword. She recounts some amusing childhood anecdotes, but discloses aspects of her relationship with her twin sister that are very personal and suggest that “all may not be well” in the land of twinship. If anything, this is the main theme of the book — twins are psychologically complicated, not just “cute” or “freaky”, and they need extra care in being parented in order to develop as individuals. The title of Chapter 1, The Ultimate Closeness: Growing Up with Your Mirror Image, immediately communicates Klein’s personal perspective. It may not be a first chapter that will draw nonidenticals into reading on. In nine chapters, Klein covers topics including Twins and Psychotherapy and Parenting Twins. Klein’s research shows that twinship is fraught with difficulties as well as fun. Twinship brings serious risks. Klein’s book is the result of indepth interviews with 30 pairs of adult twins aged from 35 to 88 years, both nonidentical and identical. She draws upon material from these twins throughout the book. Although the zygosity of the twins is sometimes mentioned and sometimes apparent from their gender differences, Klein is less interested in genetics than psychodynamics. Her section entitled Challenging the Genetic Hypothesis is unfortunately weak, seeming to be based on clinical impressions, and references to behaviour genetics studies involving comparison of identical and nonidentical twin pairs are scanty and largely ignore work from the past two decades. Nevertheless, this is not her field, and it is definitely not a book that will interest behaviour genetics researchers. Dr Klein, contentiously, places the major and overriding responsibility for the happiness and adjustment of adult twins fairly and squarely with their mothers. She acknowledges the importance of genetic influences, but her primary thesis is that the maternal bond is the crucial environmental factor in twins’ development as individuals. Therefore, in her view, based on the interviews, genetics played a lesser role than other factors. These factors include the similar timing of developmental milestones between twins, the fact that differences between twins were established early in their lives and continued to evolve, the intense competition and diffusion of ego boundaries between co-twins that leads to co-twins’ over-identification with each other, and the especially difficult adult search for a similar close relationship. There is an intensity about Klein’s book that may appeal to clinical psychologists and therapists, and possibly to twins who may have had the inadequate parenting she describes as leading to identity problems — “unit”, “interdependent” or “split” identity (the “split identity twins” have the worst time, in Klein’s view). I doubt whether the book will appeal to twins generally and their parents. It is not a very “enjoyable” read. It lacks the delightful enthusiasm and richly descriptive (but scientific) style of Nancy Segal’s Entwined Lives (Segal, 2000), in which Segal declared but transcended her own status as a nonidentical twin. Perhaps there is some significance in the difference between the worldviews of the two authors. On the other hand, perhaps identical twinship may cause more problems with adult identity, more profound problems that are not captured by the personality and mental health scales used in behaviour genetics research. On a positive note, Klein’s book may offer some helpful insights for twins who are unhappy in their twinship. Mothers of adult twins may not get much comfort from this. In the final chapter, however, Klein’s suggestions to parents for encouraging individual identity in their young twins seem very sensible, if not necessarily novel, and may deserve dissemination in a medium more accessible to parents of multiples than this book.