Further praise for No Two Alike
“Judith Rich Harris calls No Two Alike a ‘scientific detective story.’ The mystery is why people—even identical twins who grow up in the same home with the same genes—end up with different personalities. The detective is Harris herself,…who takes on the academic establishment armed only with a sharp mind and an Internet connection. Harris the author scrupulously follows clues; Harris the protagonist drives the story forward through force of character.”
—William Saletan, New York Times Book Review
“With neither a doctorate nor a university behind her, Harris more than compensates with intelligence, dogged research, lively writing, a love of mystery, and droll humor…. Harris makes behavioral genetics and evolutionary psychology enjoyable and accessible to general readers as well as scholars. Essential for general and academic libraries.”
—E. James Lieberman, Library Journal, starred review
“Harris’s writing is highly entertaining, which will help readers stick with her through the elaboration of a fairly complex theory.”
—Publishers Weekly
“Harris delivers an answer (and, yes, it’s sure to be controversial), but it’s the quest itself that will prove most fascinating for general readers, who will marvel at the step-by-step accumulation of facts, as the author marshals her argument by adeptly juggling a wide array of tools, from new theories of evolutionary psychology to behavioral genetics and linguistics.”
—David Pitt, Booklist
“There are many books about ‘human nature,’ but very few on the important question of why humans differ from one another. Judy Harris’s book is terrifically well written and interesting.”
—Robert Plomin, author of Nature and Nurture: An Introduction to Human Behavioral Genetics
“As a parent, as a social psychologist, and as a human being, I was enlightened and enthralled. Harris is an extraordinary thinker and writer: wise, witty, learned, scientifically rigorous, and absolutely fearless. Contemporary psychology has no sharper critic—and no better friend.”
—Joshua Aronson, editor of Improving Academic Achievement: Impact of Psychological Factors on Education
“Readers interested in evolutionary psychology and human development will find a lot to ponder here.”
—Science News
“Harris’s books are well worth reading for many reasons. With its roots in old-fashioned curiosity and wide learning, her exposition is a tour de force of arresting anecdotes, lively reportage, and lucid analysis.”
—Amy L. Wax, Policy Review
“When this book arrived, I pretty much sat down and read it from cover to cover—hardly my typical reaction to a nonfiction book. No Two Alike is a deeply impressive accomplishment.”
—Paul Bloom, author of Descartes’ Baby: How the Science of Child Development Explains What Makes Us Human
“There are lots and lots of goodies, including fascinating studies of memory and learning and observations of chimpanzees, chickens, paper wasps and ants. Harris shows why relationship and socialisation skills don’t necessarily go together; why bullies don’t have low self-esteem, as normally proposed; why height and earnings are related; and so on…. Her work is enjoyably well worth reading and, in this reviewer at least, stimulated much thought.”
—Denise Winn, Human Givens Journal
“Harris is not a professional scientist and isn’t afraid of ranging widely across disciplines in search of an answer. She writes with breezy good humour too, as she attempts to explain variations in personality that can’t be attributed to variations in genes.”
—Scotland on Sunday
“Why are we the way we are? Why do identical twins, raised in the same house by the same parents, turn out to have such different personalities? For years, psychologists and other professionals thought they had the answers, but this grandmotherly, iconoclastic outsider may force us to revise our thinking about these basic questions…. Mrs. Harris is an amazing woman…. As an independent scholar, she took a broader view of the issue than was possible for many of the certified experts. Perhaps that is why she has been able to see the forest, as well as the trees.”
—Peter Pettus, New York Sun
“Harris makes waves again with a new theory of personality to explain why no two people are alike…. Expect some lively rebuttals.”
—Kirkus Reviews
“I enjoyed reading this book; Harris has a conversational and engaging style that nonetheless manages to convey quite a bit of information clearly….The evidence Harris produces to support [her theory of personality] is not only persuasive but fascinating to read.”
—Mary Hrovat, Thinking Meat (thinkingmeat.com)
“Judith Harris has produced a top-notch social science text. The book takes a fresh look at research from behavioral genetics, developmental psychology, sociology, personality, and social psychology to explain, in new ways, the non-genetic causes of individual human differences…. A well-researched and thought-provoking analysis of fundamental issues in psychology.”
—Eric Lang, Science Books & Films
“The chapters on gene-environment interaction and birth order differences within families contain some fascinating detective work…. I very much enjoyed reading this book.”
—Dorret Boomsma, Nature Genetics
“Marshaling an impressive range of evidence—social psychology, anthropology, genetics, neuroscience, and, crucially, evolutionary biology—Harris demolishes entrenched orthodoxies and opens new avenues. This book will intrigue, amuse, and greatly enlighten you, whatever your personality.”
—Helena Cronin, author of The Ant and the Peacock: Altruism and Sexual Selection from Darwin to Today
“Why are identical twins reared together so different when they share all of their genes and all of the environment? Why were the Iranian conjoined twins Laleh and Ladan so different when their genes and environments seemed all but identical? No Two Alike, this wonderful new book by Judith Rich Harris, takes on this most difficult of questions…. And Harris, a devotee of mystery writing, is a great storyteller…. This is a very important book.”
—John Mullen, Metapsychology
“A truly engaging, moderately challenging take on what makes people tick. [Harris is] a plucky, ridiculously informed writer who brings potentially droll scientific studies to life, and synthesizes and picks holes in the most influential psychology studies relating to personality in the past several decades. The result is a new theory that covers all bases and explains why we are the way we are.”
—Karla Starr, Willamette Week
Also by Judith Rich Harris
The Nurture Assumption: Why Children Turn Out the Way They Do
No Two Alike
Human Nature and Human Individuality
JUDITH RICH HARRIS
W. W. NORTON & COMPANY
New York • London
To Steven Pinker
Copyright © 2006 by Judith Rich Harris
All rights reserved
For information about permission to reproduce selections from this book, write to Permissions, W. W. Norton & Company, Inc., 500 Fifth Avenue, New York, NY 10110
Library of Congress Cataloging-in-Publication Data
Harris, Judith Rich.
No two alike: human nature and human individuality / by Judith Rich Harris.—1st ed.
p. cm.
Includes bibliographical references.
ISBN: 978-0-393-32971-1
1. Individual differences. 2. Individuality. 3. Personality. I. Title.
BF697.H3765 2006
155.2—dc22
2005025837
W. W. Norton & Company, Inc., 500 Fifth Avenue, New York, N.Y. 10110 www.wwnorton.com
W. W. Norton & Company, Ltd., Castle House, 75/76 Wells Street, London W1T 3QT
Contents
Preface
1. An Appreciation of Differences
2. That Damn Rectangle
3. Monkey Business
4. Birth Order and Other Environmental Differences Within the Family
5. The Person and the Situation
6. The Modular Mind
7. The Relationship System
8. The Socialization System
9. The Status System
10. Denouement
Notes
References
Preface
HUMAN INDIVIDUALITY is a mystery. The theories of personality (or of personality development) that are currently in vogue cannot explain why no two people are alike or why they differ in the particular ways they do. Even identical twins reared in the same home differ in personality and behavior. Identical twins have identical genes, so the differences between them cannot be genetic.
The interesting differences among people are not due to genes. Nor are they due to any of the other things that the word “personality” probably made you think of. That’s why human individuality is a mystery.
My goal in this book is to solve that mystery. This is a scientific detective story.
The time is ripe for such a quest. I have tools at my disposal that the earlier theorists lacked: in particular, a new view of the human mind, based on the work of evolutionary psychologists such as Steven Pinker, Leda Cosmides, and John Tooby. The human mind, we now understand, is not simply a complex organ: it is a collection of complex organs, each serving a separate purpose, each operating according to its own rules.
But evolutionary psychology is not the only tool I bring to this quest. As an independent investigator, I have the freedom to ignore the territorial markers of the academic world and follow the trail wherever it leads me. The fields I’ve strayed into include social psychology, developmental psychology, psycholinguistics, neuroscience, and behavioral genetics. I’ve found useful clues in lots of unlikely places. Even in entomology, the study of insects.
In order to solve a mystery, one of the things a detective has to do is to examine alternative solutions and eliminate the ones that don’t work, the so-called “red herrings.” I am well equipped for that job, too: I’m a doubting Thomas, an asker of impertinent questions. If some stuffed shirt with a string of letters after his name tells me that such-and-such is true, my response is “Show me the data.” I was impertinent and skeptical even as a child, but my experiences over the past seven years—since the publication of The Nurture Assumption—have made me more so. You’ll hear that story, too, because it’s relevant to this quest.
But I don’t mean to suggest that my experiences during the past seven years have been mostly negative. On the contrary. Though health problems have kept me more or less housebound, I’ve met (mainly through e-mail) many interesting and open-minded people. One of the things I’ve learned is that a string of letters after someone’s name doesn’t necessarily make him or her a stuffed shirt.
It has been, in fact, an extraordinary seven years. You wouldn’t think that someone in my situation—no longer able to travel or to go to parties—could have such a good time. But while I’ve been stuck here in the backwaters of New Jersey, The Nurture Assumption has traveled all over the world, translated into fifteen different languages. That e-mail I mentioned comes not only from my own country but from parts of the world I’ve never seen and never will. This is my opportunity to thank all the people who have shared their thoughts with me. I’ve been edified, gratified, challenged, entertained, and sometimes moved by what you’ve told me.
I owe a debt of gratitude to many other people as well. My agent, Katinka Matson of Brockman, Inc., has always been there when I needed her, lending an ear and giving good counsel. My editor at W. W. Norton, Angela von der Lippe, made many suggestions that improved this book by making it clearer in meaning and gentler in tone. Other people at Norton whose help has been instrumental are Vanessa Levine-Smith and Renee Schwartz.
I am especially grateful to the colleagues, friends, and relatives who helped me immeasurably by reading earlier drafts of this book and giving me wise and useful feedback. A thousand thanks to the following people: Stephen L. Black, Marie Bristol-Power, Helena Cronin, Joan Friebely, Charles S. Harris, David G. Myers, Steven Pinker, Robert Plomin, Richard G. Rich, and Frederic Townsend. The advice and information they gave me were worth more than rubies.
Much more than feedback was provided by my husband of forty-four years, Charles Harris. Quite literally, he has made it possible for me to go on writing books. For the help and encouragement I’ve received from him, he has my gratitude and my love. My love, too, to the other members of my understanding and supportive family: my daughters, Nomi and Elaine, my sons-in-law, Chris and Tim, and my brother, Richard. May I mention my grandchildren, please? There are four, all bright and beautiful: Jennifer, Abigail, Jeremy, and Eleanor.
I’ve dedicated this book to Steven Pinker, who has been my e-mail friend and colleague since 1995. He has listened to my ideas, cheered me up when I’ve gotten discouraged, and argued with me when he thought I was heading in the wrong direction. Though we still don’t agree on everything, Steve has influenced my thinking more than anyone else has. Equally important, he has allowed me to influence his thinking.
Writing that, I realized that there is one more group of people who deserve my thanks: the inventors and developers of the Internet. They made it possible for someone in my situation to toss around ideas with some of the leading scientific thinkers of our time. The miracles of modern medical science have kept me alive, but the miracles of modern technology enabled me to write this book.
No Two Alike
1
An Appreciation of Differences
ON THE DAY I began writing this book, Laleh and Ladan Bijani were buried in Iran, in separate graves: apart in death as they had never been in life. Laleh and Ladan were conjoined identical twins, twenty-nine years old, born attached at the head. They died during the surgery that separated them.
In their twenty-nine years of enforced togetherness, Laleh and Ladan had accomplished more than most Iranian women of their generation: both had graduated from law school. They were able to sit and to walk because they were joined side by side, facing in the same direction. But the only way each twin could see the other’s face was by looking into a mirror.
Laleh and Ladan went into the surgery knowing the risks; physicians had told them that they had only a 50–50 chance of surviving it. They were willing to take that risk for the chance of living separate lives. “We are two completely separate individuals who are stuck to each other,” Ladan explained to reporters before the surgery. “We have different world views, we have different lifestyles, we think very differently about issues.” Laleh wanted to move to Tehran and become a journalist, while Ladan planned to remain in their hometown of Shiraz and practice law. Ladan was the more outspoken of the two, described by a close acquaintance as “very friendly, she always liked to joke.”1
The conflict in career goals was one reason they gave for undergoing the surgery. Another was their desire to see each other face-to-face without a mirror. There may have been other reasons that they didn’t admit to reporters—their desire to marry, perhaps, and to have children. Having to go everywhere with one’s sister can be a bit awkward at times. Researchers have found (and Laleh and Ladan might have discovered on their own) that someone who falls in love with one identical twin may not even like the other one.2
Though identical twinning is nature’s way of making a clone, twins are separate and unique individuals, to themselves and to the people who know them. Laleh and Ladan had identical genes and identical environments—they went everywhere together, they had no choice—but their personalities, opinions, and goals in life were different. That individuality was what they died for.
Most identical twins are not born fastened together, o
f course, and most conjoined twins do not seek surgical separation in adulthood. But identical twins invariably differ in personality. Why they differ is a mystery that science has so far been unable to solve and that twins themselves are puzzled by.
“Why am I me?” That question was put to Freeman Dyson, professor of physics at the Institute for Advanced Study at Princeton, by his eight-year-old grandson George. I don’t know what he said to George, but Dyson later told an adult audience that the question “summarizes the conundrum of personal existence in an impersonal universe.” Um, I suppose so. But the question had a more specific meaning for George, because he is an identical twin. According to his grandfather, George knows the difference between identical (monozygotic) and fraternal (dizygotic) twins, and he knows that he and his twin brother Donald are genetically identical. He is also aware, according to his grandfather, that he and his twin “have the same environment and upbringing”—they are growing up in the same home with the same parents. When George asked “Why am I me?” he was asking, his grandfather gathered, “how it happens that two people with identical genes and identical nurture are nevertheless different.”3 If their nature is the same and their nurture is the same, how come they have different personalities?
Human individuality and human differences are the subject matter of this book. Though twins present the problem in a nutshell, the differences between ordinary siblings are just as mysterious and just as unexplained. And if scientists cannot explain why twins are different and why ordinary siblings are different, it means they also can’t explain why you and I, or any two people picked at random, are different.
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