From Publishers Weekly
Why do identical twins who grow up together differ in personality? Harris attempts to solve that mystery. Her initial thesis in The Nurture Assumption: Why Children Turn Out the Way They Do
is replaced here with a stronger, more detailed one based on evolutionary psychology. Reading this book is akin to working your way through a mystery novel—complete with periodic references to Sherlock Holmes. And Harris has a knack for interspersing scientific and research-laden text with personal anecdotes. Initially, she refutes five red herring theories of personality differences, including differences in environment and gene-environment interactions. Eventually, Harris presents her own theory, starting from modular notions of the brain (as Steven Pinker puts it, "the mind is not a single organ but a system of organs"). Harris offers a three-systems theory of personality: there's the relationship system, the socialization system and the status system. And while she admits her theory of personality isn't simple, it is thought provoking. Harris ties up the loose ends of the new theory, showing how the development of the three systems creates personality. Harris's writing is highly entertaining, which will help readers stick with her through the elaboration of a fairly complex theory. 12 b&w illus. (Feb.)
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From Scientific American
Where does adult personality come from? Why are we all different? These are the questions energizing Judith Rich Harriss new book.
Harris, a former textbook author turned popular writer, dives right in, sharpening her focus by looking at identical twins. After subtracting the share contributed by their mutual genesabout 45 percentstudies show that adult identical twins are no more alike in personality than people plucked at random from a crowd, even though the siblings were raised in the same home, by the same parents, with identical schooling.
Where, then, do personality differences come from? Harris begins, in a savage fashion familiar to readers of her Nurture Assumption, by recounting factors that do not contribute to personality differences. She debunks dozens of studies by psychologistsespecially the "developmentalists" and "interventionists" who believe that better parenting or school environments can affect how children turn outby pointing out where they have fudged numbers and twisted results. She rejects the basis of psychoanalysis, stating there is no evidence that talking about childhood experiences has therapeutic value. She also maintains that learned behaviors do not readily transfer from one situation to another, noting that even babies behave differently to fit different environments.
To answer her opening questions, Harris then develops a complex scheme based on "the modular mind," a framework set forth by Harvard University evolutionary psychologist Steven Pinker and others. (Harris herself has no doctorate and is housebound by systemic sclerosis and lupus, two autoimmune disorders.) She describes three modulesthe relationship system, the socialization system and the status systemand explains how each contributes its part to making us who we are. The relationship system starts in the cradle as infants study and learn the faces and voices of the people around them, collecting information that helps form personality. The socialization system adapts people to their culture. The status system takes all the information collected during childhood and adolescence and shapes and modifies our personalities in accord with our environments.
Harriss last chapter lays out her theory in tabular form, explaining how each module interacts with the others to produce our distinct personalities. It is lavishly footnoted, like the rest of the book, shoring up her strategy of pointing out the failings of other models and then proposing her own. Her goal, she writes, is to explain the variations in personality that cannot be attributed to variations in peoples genes. After saying she believes she has succeeded, she throws down her gauntlet: "I will leave it to other people to test my theory."