No Two Alike: Human Nature and Human Individuality [Paperback]

Judith Rich Harris (Author)

Book Description

Publication Date: June 17, 2007

A groundbreaking theory of personality.

The author of the controversial book The Nurture Assumption tackles the biggest mystery in all of psychology: What makes people differ so much in personality and behavior? It can't just be "nature and nurture," because even identical twins who grow up together—same genes, same parents—have different personalities. And if psychologists can't explain why identical twins are different, they also can't explain why each of us differs from everyone else. Why no two people are alike.

Harris turns out to be well suited for the role of detective—it isn't easy to pull the wool over her eyes. She rounds up the usual suspects and shows why none of the currently popular explanations for human differences—birth order effects, for example, or interactions between genes and environment—can be the perpetrator she is looking for. None of these theories can solve the mystery of human individuality.

The search for clues carries Harris into some fascinating byways of science. The evidence she examines ranges from classic experiments in social psychology to cutting-edge research in neuroscience. She looks at studies of twins, research on autistic children, observations of chimpanzees, birds, and even ants.

Her solution is a startlingly original one: the first completely new theory of personality since Freud's. Based on a principle of evolutionary psychology—the idea that the human mind is a toolbox of special-purpose devices—Harris's theory explains how attributes we all have in common can make us different.

This is the story of a scientific quest, but it is also the personal story of a courageous and innovative woman who refused to be satisfied with "what everyone knows is true."

12 illustrations

Product Details

• Paperback: 352 pages
• Publisher: W. W. Norton & Company; Reprint edition (June 17, 2007)
• Language: English
• ISBN-10: 0393329712
• ISBN-13: 978-0393329711
• Product Dimensions: 0.9 x 5.5 x 8.3 inches
• Shipping Weight: 11.2 ounces (View shipping rates and policies)
• Average Customer Review: 4.0 out of 5 stars  See all reviews (25 customer reviews)
• Amazon Best Sellers Rank: #469,427 in Books (See Top 100 in Books)

Editorial Reviews

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.)
Copyright © Reed Business Information, a division of Reed Elsevier Inc. All rights reserved. --This text refers to an out of print or unavailable edition of this title.

From Scientific American

Where does adult personality come from? Why are we all different? These are the questions energizing Judith Rich Harris’s 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 genes—about 45 percent—studies 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 psychologists—especially the "developmentalists" and "interventionists" who believe that better parenting or school environments can affect how children turn out—by 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 modules—the relationship system, the socialization system and the status system—and 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.

Harris’s 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 people’s genes. After saying she believes she has succeeded, she throws down her gauntlet: "I will leave it to other people to test my theory."

Jonathan Beard --This text refers to an out of print or unavailable edition of this title.

See all Editorial Reviews

Product Details

• Paperback: 352 pages
• Publisher: W. W. Norton & Company; Reprint edition (June 17, 2007)
• Language: English
• ISBN-10: 0393329712
• ISBN-13: 978-0393329711
• Product Dimensions: 0.9 x 5.5 x 8.3 inches
• Shipping Weight: 11.2 ounces (View shipping rates and policies)
• Average Customer Review: 4.0 out of 5 stars  See all reviews (25 customer reviews)
• Amazon Best Sellers Rank: #469,427 in Books (See Top 100 in Books)

More About the Author

Discover books, learn about writers, read author blogs, and more.

Most Helpful Customer Reviews

78 of 81 people found the following review helpful

5.0 out of 5 stars An Intriguing New Theory of Personality February 27, 2006

By The Spinozanator VINE™ VOICE

Format:Hardcover

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 another." Learning is context sensitive.

Important aspects of her theory: Harris draws on many fields, particularly evolutionary psychology and behavioral genetics. She apologizes that her theory is not simple, and blames it on Einstein, who said, "Make things as simple as you can, but no simpler," and suggests that by the year 2050, elaborations on it (her theory) will make her theory of today look simple indeed.

Genes: Genes are responsible for ~45% of personality. We are looking for the perpetrator of the ~55% "unexplained variance" of personality.

Modules: In searching for the perp, we will assume various specialty "modules" in the brain. Like Chomsky's linguistic module, they perform unique functions. They are intricate networks in the brain - some are known to have a specific location but others may be more diffuse. Some of the modules are: facial recognition, mental lexicon about people, mind-reading mechanism, categorization (stereotyping), prototype calculator, eye-gaze detector and counter, language, relationship sociometer, group-acceptance sociometer, and status sociometer. These tools are available for use by the three separate departments of the mind.

The three departments: The relationship system, the socialization system, and the status (competing) system are all products of evolution, have three different tasks, work in different ways, and we need all three to explain how environment shapes personality. Each receives a different combination of information from the modules, sometimes the information is conflicting, they process the information differently, they trigger different emotions, and all three provide their own inherent motivation.

The relationship system is responsible for making and maintaining individual favorable relationships, and is under conscious control. The socialization system makes you want to gain group acceptance and shows you how, and operates mostly outside of conscious awareness. The status system ensures that you will compete with rivals and attempt to maximize your status, under mostly conscious control. One or more of these systems is the perpetrator that is capable of causing personality differences that are unrelated to differences in genes and causes even identical twins to have differing personalities. The author explains her theory thoroughly and persuasively, and names the culprit(s) at the end.

This book and "Nurture Assumption" are a breath of fresh air for those of us who have had difficult children. My record is four difficult out of six. I'm not bragging that our parenting skills were great, but my wife and I tried to the best of our abilities. Those four out of the house are all happy, productive, we see them frequently - but that doesn't reflect the angst over the prospect of the guilt we certainly thought we would be deserving of had any of them (perish the thought) ended up unhappy (jailed, mentally ill, depressed, etc.).

I predict both these books will become classics - and "No Two Alike" will impress, enthrall, and enlighten you - five well-deserved stars. Read more ›

33 of 34 people found the following review helpful

3.0 out of 5 stars disappointing September 10, 2006

By Sioran

Format:Hardcover

I really love "The Nurture Assumption". I bought multiple copies to my relatives, friends and colleagues, and some of them bought additional copies to their friends and colleagues. I thought the major thesis of that book was confused, but the insight into the role of peer groups was both highly original and true. Harrris' failure at Harvard and her subsequent success, certified, among others, by the very people who found her incompetent many years ago, felt moving and most inspiring. Harris' childhood experience of peer-rejection as well as her illness brought additional layer of charm and humanity to her excellent writing. The writing remained quite good in the "No Two Alike" and the sense of humor is still there, although I find it to be a little bit too crude in both books. But most of the other qualities are lost.

In "No Two Alike" Harris admits that she had previously confused socialization (a process that makes people alike) and personality development (a process that makes people different), and now proposes a new theory that will address the latter. Again, her goal is to explain why there are personality differences between identical twins (including those raised together). The proposed theory is different from the previous one and less obviously confused. It is also much less original and must less interesting. According to Harris this time, what makes identical twins differ is, at the bottom, that other people's opinions of them are different. And they are different, because twins are different individuals for whom other people store information separately. She doesn't say it this way, and in any case, she appears to think that this is a very different explanation from simply saying that unexplained variance in personality is due to noise.... But for most purposes, including all practical purposes, this is what her solution implies.

This is a rather disappointing ending, especially since Harris early on explicitly rejects noise as the sole cause of these differences. We are led, or mislead, to believe that she is going to identify a major, so far overlooked factor or factors, something like peer culture, but actually capable of producing differences among identical twins that peer groups can't produce, because identical twins belong to the same peer group. It takes Harris 208 pages (the book without notes has 265) to even start talking about the actual explanation for the differences. The first 208 pages contain mostly unnecessary, repetitive and annoyingly boastful rehash of issues already covered it the previous book as well as many other places. I often found myself impatiently peeking at the last pages of the book where the solution will finally be revealed.

There are reasons why Harris thinks she is proposing something new, and to an extent she is, but it is not a new view of the causes for personality differences among identical twins. It is not even a new personality theory, because personality theory to which Harris implicitly ascribes is a standard trait model of personality. It is, roughly, a theory of a person's social cognition. It postulates three separate systems that in different ways process social information. These three systems are relationship system, which keeps track of information regarding particular persons, socialization system that keeps track of cultural averages for categories of people, and status-system, which keeps track of what other people think about you, averages those opinions, and modifies behavior to optimize your status in particular contexts. The idea that people have something akin to dictionary of other people is cute, and the idea that we use mind-reading to uncover what other people have "written" about us in their dictionaries is one of the very few original ideas in the book.

The theory is silent on any specifics of the environment that would produce a personality in an identical twin that is higher, on, say, neuroticism, than that of his brother. The theory claims, basically, that something must have happened that made higher neuroticism produce better results status-wise (when averaged across all contexts) for the more neurotic twin. That something is often a result of a random event whose consequences got reinforced because twins are perceived as separate individuals in the eyes of others, and these different perceptions amount to different, non-shared environments to which they are exposed. The additional claim that status-system basically adaptively magnifies differences from others, including one's twin, leaves unclear of why many choose to be mediocre doctors as opposed to outstanding janitors. These observations are not meant to be refutations of the theory but illustrations that the level of precision in the short, truly substantive part of the book is distressingly low, especially when compared to the needlessly elaborate introduction. It feels as if Harris prematurely published her book, without seriously thinking through the implications of her model.

There is no doubt that we know and want to know about other people, that we know and want to know what they think of us and that any theory of human social life has to acknowledge these skills and interests. But there are many ways these can be acknowledged, and Harris's theory already has several problems. As she herself admits, impairment to those presumably independent modules seems to come (as in autistic children) together rather than independently. Another one is that, despite her hope, brain-scan studies do not, by itself, deliver the number of modules and separate processes in the mind: the interpretation of these differences in brain activation crucially depends on the theory used. There are always some differences, if you want to look closely enough, and none, if you don't. A third one is an inconsistent treatment of socialization module by Harris. She claims that everybody gets socialized, and then, in parallel, that failure to get socialized produces subtle personality differences. To illustrate these difference Harris uses her own example, interpreting her "independent mind" as a result of, you know, intrinsic lack of desire to conform to the prosaic norms of the group.

Which brings me to the last point. Harris herself is a nice example that personality can indeed change well into the sixties, depending on one's perception in the eyes of others. While I, for the most part, liked the persona that emerged from "The Nurture Assumption" this one is rather less appealing. Plainly, Harris comes across as narcissistic and self-righteous. She needlessly spoon-feeds her divine properties to the readers, describing herself as independent-minded and broadly educated, rather than letting us conclude that on our own (as many of us already had). She insists that she has been under-estimated by the establishment, and that is no doubt true, but, boy, does she under-estimate the establishment! Apparently, she spent a lot of time interacting with a couple of straw-men and her socialization module told her that that is what her competitors look like. They don't. I was almost embarrassed when I read her boastful pronouncements of variety of fields she is allegedly competent in, while almost all information she presented from those various fields were elementary and common-place. I, for example, am only a graduate student who only has at best a tertiary interest in personality development, yet I was familiar with almost all points and examples that she mentioned. Admittedly, though, I haven't yet managed to get kicked out of the graduate program. Read more ›

25 of 26 people found the following review helpful

4.0 out of 5 stars It Had To Be You May 10, 2006

By G. Bestick VINE™ VOICE

Format:Hardcover|Amazon Verified Purchase

One of the more fascinating aspects of being human is that we're all built from the same parts, yet we all have different personalities. What makes you you and me me? Confronted with this question, most people would respond that it's some blend of nature (the genes you inherited from your parents) and nurture (the environment you were raised in). Judith Rich Harris debunks that answer and replaces it with an elegant hypothesis about the true sources of human uniqueness.

In the first part of her book, Harris takes developmental and social psychologists to task for over-emphasizing the influence of early childhood experiences on personality formation and not giving enough credit to what happens outside the home. She also maintains that developmental studies that don't screen for genetic influences are prone to confuse cause and effect. She shows how research that's been inadequately digested makes its way into mainstream culture, where it's regurgitated as pop truth. According to Harris, most of the conventional wisdom about birth order, home environment, parenting style, and the interaction of genes and the home environment does not adequately explain why we're different from one other.

Having eliminated the usual suspects, Harris turns to Stephen Pinker's How The Mind Works as her starting point for solving the mystery of human personality. Pinker posits that our brains are organized into "mental modules" that perform discrete tasks. Some examples of modular systems are facial recognition, language acquisition, and our ability to postulate what other people are thinking (a theory of mind). All of these had evolutionary value to small tribes of wandering hominids, and evolved to better serve our survival needs....

Harris' theory is that once we've figured out what part of a personality is accounted for by genes (a little less than half if you average the various studies), the remainder of a personality is created through the interplay of three mental systems: the relationship system, the socialization system, and the status system. Each of these systems evolved to deal with a pressing survival issue. The relationship system helps us attach to, and later relate to, specific individuals. The socialization system enables us to figure out the norms of our group so we can fit in. The relationship system is with us at birth, and the socialization system develops quite early in life. The slowest system to emerge is the status system, which we use to set ourselves apart from the other members of our group. The status system takes longest to develop because we need to be intellectually sophisticated enough to figure out who we are and what we're good at.

These systems can issue contradictory directives. For instance, the generalizations of the social system war with the specificity of the relationship system. This explains why a person can dislike an ethnic group while getting along perfectly well with a neighbor who happens to be a member of that group. The socialization and status systems are often at odds: do I sacrifice my personal goals for the good of the group, or do what's best for me even if it harms the others? Most of a life's high drama involves trade-offs among these systems. What makes you unique among all the humans who have ever trod the planet is the way your mental modules process the stimulus provided by your particular environment.

I wish we had more detail on how Harris' mental systems work. For instance, language acquisition theorists continue to go round on how much of our language facility is innate versus how much is instantiated by experience. Just as we have to memorize a lot of specific words to speak a language, we have to organize a lot of data - particular faces, facts about the people attached to those faces, rules, norms and prototypes of groups, specific information about our own skills and how people view us - to populate Harris' mental modules. Does the framework - eg grammar rules or the relationship module - precede the data, or does it emerge as the data is acquired? If the three systems are more innate than experiential, does this mean that more of our personality is influenced by genes than we currently believe? If it's experiential, by what process do we generate the proper responses to a specific situation? What triggers the appropriate neural assemblies and how do we make trade-offs between specific information and general rules?

As Harris herself states, her theory needs to researched, tested and validated. The really exciting breakthroughs will come when we're able to correlate observational studies of human behavior with the genes and genetic switches that activate those behaviors. Behavioral geneticists are advancing into this new territory, which will help us lift the analysis of human personality out of the realm of metaphor and into the realm of hard science. Meanwhile, Harris has given us an elegant hypothesis, rich in implications, written in a clear and entertaining manner. As a theory, it explains an immense amount about why you're you and I'm me. Read more ›