The Trouble with Twin Studies

The Trouble with Twin Studies questions popular genetic explanations of human behavioral differences based upon the existing body of twin research. Psychologist Jay Joseph outlines the fallacies of twin studies in the context of the ongoing decades-long failure to discover genes for human behavioral differences, including IQ, personality, and the major psychiatric disorders. This volume critically examines twin research, with a special emphasis on reared-apart twin studies, and incorporates new and updated perspectives, analyses, arguments, and evidence.

Jay Joseph, PsyD., is a licensed psychologist practicing in the San Francisco Bay Area. Since 1998 he has published two books, several book chapters, and many articles in peer reviewed journals, where he has presented a critical appraisal of genetic theories and research in psychiatry and psychology.

Preface. Part I: Studies of Twins Reared-Apart 1. Introduction 2. Studies of Reared-Apart Twins: Origins, Publications, and Scandal 3. Studies of Reared-Apart Twins: The Critics Respond 4. Studies of Reared-Apart Twins: Basic Assumptions and Potential Fallacies 5. The Minnesota Study of Twins Reared-Apart I: Biases, Assumptions and Other Problem Areas 6. The Minnesota Study of Twins Reared-Apart II: IQ and Personality Studies Part II: Studies of Reared-Together Twins 7. The MZT-DZT Equal Environment Assumption: The Achilles Heel of the Classical Twin Method 8. Twin Research in Psychiatry Part III: Approaching a Post-Behavioral Genetics Era? 9. Molecular Genetic Research: The Ultimate Test of Genetic Interpretations of Twin Studies 10. The Crumbling Pillars of Behavioral Genetics 11. A Human Genetics Parable 12. Summary and Conclusions. Appendices. References.