No Two Alike: Human Nature and Human Individuality

This new book by Judith Rich Harris is again thought provoking. In the book, which is written like a scientific detective, she tries to solve the mystery of individual differences between people. According to the current scientific knowledge, roughly 45% of these differences can be attributed to genes. But this leaves 55% of unexplained variance. How can this be explained? The book is roughly divided in two parts. The first chapters are used to eliminate some possible causal factors. Individual differences are not caused by differences in environment and not by a combination of genes and upbringing. Interactions between genes and environment can also be ruled out just like environmental differences within families and correlations between genes and environment. In the second part of the book Rich Harris presents a new theory. Briefly summarized the author proposes that individual differences are caused by a cooperation between two brain systems, the relationship system and the status system. I like this book. It is challenging, thoughful and thought-provoking. The most convincing part of the book, according to me, is the first part, in which she debunks some broadly held convictions among laymen and scientists.

Judith Rich Harris has devised a solution to the second half of the puzzle she set herself a decade ago. John Locke proposed three centuries ago that a baby enters the world as a blank slate, tabula rasa in Latin, upon which worldly experience writes, and in doing so forms the adult. Per Harris' title, each of us is quite unique. The process by which we attain our uniqueness has occupied philosophers and scientists for centuries. I begin with a caution to the reader. Do not search your mental library for a template to pre-apply to Harris' book. You don't have one. It is not Nature vs. Nurture redux. Not genetic determinism. This is a fresh assemblage of ideas, pulled together from a number of realms of contemporary science, to be approached with a fresh and open mind. The history of the science upon which she draws is full of strong personalities and opinions, drawing on and shaping the intellectual currents of their times: Galton, with his belief that human ability and character were inherited; Skinner and Watson, who believed in the potency of environmental interventions and the malleability of human nature (a belief shared by generations of educators). This is the baggage Harris asks you to throw aside. Neither Galton's nor Skinner's model comes close to explaining human nature as we experience it. What, then, does? 45% of individual differences - Harris focuses on personality, but other researchers find it to be true of other traits such as cognitive ability - are inherited. This was one of the principal arguments of Harris' 1998 "The Nurture Assumption." The second major argument concerned what did not account for the other 55%. After controlling for genetics, parents' influence on children's personalities, language and values is minimal. These are testable hypothesis: simply look at twins raised together and apart, and blood siblings vs. adoptive siblings under the same roof. The book posed a serious threat to the dominant model. It exculpated generations from the parental guilt imposed by Freud and his followers, and challenged parents' and educators' sense of their own importance in forming a child. Harris got into some nasty academic mudslinging, and takes delicious pleasure in recounting her victories in "No Two Alike." It is exactly the kind of gossip upon which humankind, per her thesis, thrives, and I relished it. That still leaves 55% of the variance in human personality unaccounted for. What are the culprits? Harris crafted the book like a mystery novel, lining up the usual suspects one by one and dismissing them: (1) home environments, (2) child rearing practices, (3) gene-environment interactions, (4) birth order, and (5) gene-environment correlations. 1,2 and 4 are self-evident. Concepts (3) and (5) take some understanding of genetics and statistics. (3) might say that an environmental factor - harsh discipline, say - might make tall children less aggressive and short children more aggressive, with

For someone nearly housebound and bereft of academic qualifications, Harris is an imposing figure in the world of social behaviour. Her earlier book having raised a storm of controversy among academics, this one will extend the arena to family relations. There is probably no greater shibboleth than the notion that parents are wholly responsible for how their children develop. In this book, Harris demolishes that idea. She applies the mode of a "detective story" to line up evidence and possible perpetrators. Although much of the focus in this book relies on the study of twins, she also raises the issue of birth order and how each of us interacts at home, school and social contact. With an easy, conversational style and use of much evidence, Harris has once again built a cogent and convincing argument. As with every "detective novel", the investigator must eliminate possible perpetrators. Harris defines a number of "red herrings" that she must dispense with prior to presenting her own thesis of what drives our relationships with others. Among the outdated or mistaken ideas she tackles are those of Freud and the "blank slate" aficionados. This latter has come to dominate both academic and family thinking about raising offspring. Whatever the shifting fashions of psychology have favoured, the one element long overlooked has been the evolutionary basis of family development. The growing field of evolutionary psychology is helping to fill that gap. Harris draws on many scholars of the past generation in support of her desire to call attention to our genetic roots. Steven Pinker, John Tooby and Leda Cosmides loom large in her narrative. Skirting the term "sociobiology" as likely too inflammatory, she still pays homage to Edward O. Wilson's efforts to equate the social species of our world. One of the major targets of her updating of social thinking is the "correlation". It's possible to measure a child's behaviour and that of its family. The flaw in the research has been to assign cause through correlation. Harris contends there's no evidence to support the link. While most families regard themselves as at least guiding their offspring's behaviour, she shows that it's equally likely the child is driving theirs. With nearly half a child's conduct due to genetic drive, attributing traits to parental influence alone has little basis. Moreover, many home behaviours are shed when the child departs the home for school. An entire new set of rules for interaction arise in the classroom and playground. There, the issues of acceptance in various groups become the dominant concern. Classroom performance influences how one is viewed by peers, as is physique, deportment and understanding rank. These are complex issues, strongly interacting. Even sibling rivalry seems simple by comparison. There, the dealings are with only a few in a relatively fixed environment. Outside the home, the situation becomes almost infinitely complex. Yet, th

[...] In point of fact, Harris graduated magna cum laude from Brandeis in 1959 and was awarded the Lila Pearlman Prize in psychology. In 1961 she received a master's degree in psychology from Harvard University. After receiving her master's degree, Harris worked as a teaching assistant in psychology at MIT (1961-1962), and as a research assistant at Bolt Beranek and Newman (1962-1963) and the University of Pennsylvania (1963-1965). Her academic career was effectively halted by two things...the birth of her children and a chronic autoimmune disorder that has been diagnosed as a combination of lupus and systemic sclerosis. She spent the late 70's bedridden. From 1981 to 1994 she was a writer of textbooks in developmental psychology In sum, even if she holds no doctorate, Harris is a highly trained psychologist, with experience in academia and more than a decade under her belt as a writer of developmental textbooks. Specifically regarding "No Two Alike: Human Nature and Human Individuality," it must be taken first and foremost as a rebuttal to the objections raised to her groundbreaking book "The Nurture Assumption." In doing so, she covers much of the same ground, but this time lays waste to "academic" responses from the likes of Stephen Suomi and Frank Sulloway. "The Nurture Assumption" laid out a frame work for the development of personality. "No Two Alike" defends and expands her work. Right now...everyone else is just playing catch-up.

Judith Rich Harris is the controversial author of "The Nurture Assumption." She holds no PhD degree and is affiliated with no prestigious institutions, yet her book was a finalist for the Pulitzer Prize. "No Two Alike" is somewhat of a memoir of her research and the writing of these two books. She has obviously been meticulous about her fact-finding and more than one bad study and sloppy researcher has suffered embarrassment (if not exposure) under her scrutiny. In "Nurture Assumption," Harris took on most authorities in developmental psychology, who seemed to think that if a kid didn't turn out just right (whatever that meant) that kid was assumed to have received sub-par parenting...certain interventions could and should have been done that would have brought about a better result. Never in world history had so much blame been placed on parents, and Harris didn't buy it. In her opinion, childhood environmental influence that lasts into adulthood didn't come from parents. It came from the child's peer group, and she produced reams of research to prove it. Harris wrote child development texts for several years, drawing on authorities from many fields of study. The discrepancies amongst disciplines led her to believe that the academics must never read each others' research. One day she realized she simply didn't believe what she was writing. This nagging thought led her to do her own survey of the literature, which eventually inspired her to write "Nurture Assumption." She continues along the same lines of thought in "No Two Alike," but concentrates on related questions: If personality characteristics aren't molded at home, how are they molded? What is so important about the peer group? Why do even identical twins sometimes have diversely different personalities and outcomes? In "No Two Alike," Harris approaches the above questions as if she were a detective - and ends up presenting the first full theory of personality since Freud. Her recurring theme about the status of developmental research: All research that looks at individual differences has to have some way of controlling for the direct and indirect effects of heredity, yet most past and present studies in socialization and developmental psychology don't control for genes and are not double blind. Partly because of the design of most studies, partly because variables in the environment are limitless, preconceptual bias is a real problem. First half of the book: She lists the five red herrings academic psychologists have advocated as influential in child development - then carefully dismisses them all, showing that none of the simpler theories hold up to valid research. "I can eliminate all the currently popular theories of personality development with a single flick of my hand, because they all rest on the same basic assumption about learning: that learned behaviors or learned associations transfer readily and automatically from one situation to anothe