Contents
About the Authors xv
Preface xvii
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Overview 1
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Mendel's Laws of Heredity 6
Mendel’s First Law of Heredity 7
Gregor Mendel’s Luck 8
Huntington Disease 10
Phenylketonuria 11
How Do We Know That 1 in 50 People Are
Carriers for PKU? 13
Mendel’s Second Law of Heredity 14
Summary 18
Beyond Mendel's Laws 20
Genes on the X Chromosome 21

Other Exceptions to Mendel’s laws 23
New Mutations 23
Changes in Chromosomes 23
Expanded Triplet Repeats 25
Genomic Imprinting 26
Complex Traits 28
Schizophrenia 28
General Cognitive Ability 29
Pea Size 30
Multiple-Gene Inheritance 32
Quantitative Genetics 34
Liability-Threshold Model of Disorders 36
Summary 38
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DNA: The Basis of Heredity 39
DNA 39
B«i*Ki ’ The “Central Dogma” of Molecular Genetics 44
Chromosomes 46
Summary 49
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Animal Models in Behavioral Genetics 50
Quantitative Genetic Experiments to Investigate Animal Behavior 50
Selection Studies 52
Inbred Strain Studies 57
Animal Studies for Identifying Genes and Gene Functions 60
Creating Mutations 61
Quantitative Trait Loci 66
Synteny Homology 71
Summary 71
Nature, Nurture, and Human Behavior 73
Investigating the Genetics of Human Behavior 74
Adoption Designs 74

BOX 6.1
BOX 6.2
The First Adoption Study of Schizophrenia 77
Issues in Adoption Studies 78
Twin Design 78
The Twin Method 82
BOX 6.3
Combination 84
Summary 85
CHAPTE
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Estimating Genetic and Environmental Influences 86
Heritability 86
Interpreting Heritability 89
BOX 7.1
Estimating Quantitative Genetic Parameters
Directly from DNA 90
Environmentality 95
Shared Environment 96
Nonshared Environment 96
Estimating Shared and Nonshared Environmental Influences 97
Identifying Specific Nonshared Environment 98 Identifying Specific Nonshared Environment That Predicts
Behavioral Outcomes 100
Multivariate Analysis 102
Summary 103
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The Interplay between Genes and Environment 105
Beyond Heritability 106
Genotype-Environment Correlation 107
The Nature of Nurture 108
Three Types of Genotype-Environment Correlation 111 Three Methods to Detect Genotype-Environment Correlation 112
Implications 117
Genotype-Environment Interaction 118
Animal Models 120
Adoption Studies 120

Twin Studies 122
DNA 123
Summary 126
Identifying Genes 128
Mutations 129
Detecting Polymorphisms 130
DNA Markers 132
Human Behavior 134
Linkage: Single-Gene Disorders 135
Linkage: Complex Disorders 137
Association: Candidate Genes 137
Affected Sib-Pair Linkage Design 138
Association: Genomewide 139
SNP Microarrays 140
Summary 143
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Pathways between Genes and Behavior 144
U23B0DI Levels of Analysis 145
Gene Expression and the Role of Epigenetics 146 The Transcriptome: Gene Expression throughout the
Genome 149 Gene Expression Profiles: RNA Microarrays and
Sequence-Based Approaches 149
Genetical Genomics 151 Gene Expression as a Biological Basis for Environmental
Influence 152
The Proteome: Proteins Coded throughout the Transcriptome 153
The Brain 155
Endophenotypes 156
Learning and Memory 157

Emotion 160
Summary 162
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Cognitive Disabilities 163
General Cognitive Disability: Quantitative Genetics 164
General Cognitive Disability: Single-Gene Disorders 165
Phenylkonuria 165
Fragile X Syndrome 166
Rett Syndrome 168
Other Single-Gene Disorders 168
General Cognitive Disability: Chromosomal Abnormalities 170
Down Syndrome 170
Sex Chromosome Abnormalities 171
Specific Cognitive Disabilities 174
Reading Disability 175
wzsmwM DF Extremes Analysis 176
Communication Disorders 180
Mathematics Disability 181
Comorbidity among Specific Cognitive Disabilities 181
Dementia 181
Summary 183
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General Cognitive Ability 186
Historical Highlights 188
Animal Research 188
Francis Galton 190
Human Research 193
Overview of Genetic Research 194
Genetic Influence 194
Environmental Influence 196
Assortative Mating 197
Nonadditive Genetic Variance 198
Developmental Research 200
Does Heritability Change during Development? 200

Do Genetic Factors Contribute to Developmental
Change? 204
Identifying Genes 206
Summary 209
Specific Cognitive Abilities 210
Broad Factors of Specific Cognitive Abilities 210
Multivariate Genetic Analysis 217
Information-Processing Measures 218
Working Memory Model 220
Imaging Genetics 220
School Achievement 222
Identifying Genes 228
Summary 229
Schizophrenia 230
Family Studies 231
The Beginnings of Psychiatric Genetics:
Bethlem Royal and Maudsley Hospitals 232
Twin Studies 234
Adoption Studies 236
Schizophrenia or Schizophrenias? 238
Identifying Genes 239
Summary 241
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Other Adult Psychopathology 242
Mood Disorders 242
Family Studies 243
Twin Studies 245
Adoption Studies 246
Identifying Genes 247

Anxiety Disorders 248
Other Disorders 250
Co-Occurrence of Disorders 252
Identifying Genes 255
Summary 256
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Developmental Psychopathology 257
Autism 258
Family and Twin Studies 258
Identifying Genes 260
Attention-Deficit and Disruptive Behavior Disorders 261
Twin Studies 262
Identifying Genes 265
Anxiety Disorders 266
Other Disorders 268
Overview of Twin Studies of Childhood Disorders 270
Summary 270
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Personality and Personality Disorders 273
Self-Report Questionnaires 274
Other Measures of Personality 277
Other Findings 279
Situations 279
Development 279
Nature-Nurture Interplay 280
Personality and Social Psychology 280
Relationships 281
Self-Esteem 283
Attitudes and Interests 284
Behavioral Economics 285
Personality Disorders 285
Schizotypal Personality Disorder 287
Obsessive-Compulsive Personality Disorder 288
Antisocial Personality Disorder and Criminal Behavior 288
Identifying Genes 292
Summary 295

Substance Use Disorders 297
Alcohol Dependence 297 Twin and Adoption Research on Alcohol-Related
Phenotypes 297
Animal Research on Alcohol-Related Phenotypes 299 Molecular Genetic Research on Alcohol-Related
Phenotypes 302
Nicotine Dependence 306
Twin Research on Smoking-Related Phenotypes 307 Molecular Genetic Research on Smoking-Related
Phenotypes 309
Other Drugs 311
Complexities of Studying the Genetics of Substance Use 312
Summary 313
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Health Psychology and Aging 314
Health Psychology 314
Body Weight and Obesity 315
Subjective Well-Being and Health 322
Psychology and Aging 323
Health Psychology and Genetic Counseling 327
Genetic Counseling 328
Summary 329
Evolution and Behavior 330
Charles Darwin 330
Inclusive Fitness 334
Population Genetics 336
Evolutionary Genomics 338
Evolutionary Psychology 339
Instincts 340
Empirical Evidence 341
Mate Preference and the Major Histocompatibility
Complex 342

Mate Selection for Facial Characteristics 344
Summary 346
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The Future of Behavioral Genetics 348
Quantitative Genetics 348
Molecular Genetics 352
Implications of Nature and Nurture 354
Statistical Methods in Behavioral Genetics 357
1 Introduction 357
Behavioral Genetic Interactive Modules 358
> About the Author 359
1.1 Variation and Covariation: Statistical Descriptions of Individual Differences 360
2 Quantitative Genetics 373
2.1 The Biometric Model 373
2.2 Estimating Variance Components 378
3 Molecular Genetics 402
3.1 Linkage Analysis 403
3.2 Association Analysis 406