Twins As A Tool Of Behavioral Genetics

Twins as a Tool of Behavioral Genetics Edited by T. J. Bouchard, Jr. P. Propping Every human being is genetically unique and consequently genetically different from every other human being. The one exception is identical (monozygotic) twins, who share exactly the same genome. Fraternal (dizygotic) twins share half of their genes in common by descent. Twins of both types constitute "an experiment of nature". Because it is unethical to carry out powerful experiments on human beings in order to explore the causes of variation in human traits, this natural experiment with all of its vicissitudes is one of the few windows we have with which to view the genetic and environmental determinants of complex human behavioral traits. Many scientists believe that twins can only be used to estimate "heritability" and that they reveal nothing about how genes influence behavior. In addition, they argue that modern molecular genetics will quickly make twin research obsolete. These widely held views are largely incorrect. Twins are a unique and very powerful tool for exploring a wide variety of hypotheses about both the distal (mostly genetic) and proximal (mostly environmental) origins of human individual differences. Scientific knowledge accumulates most rapidly when scientists ask the right questions and utilize the right tools—the right tools for the job. This book attempts to highlight the questions that might be most productively addressed through the use of twin designs. Every tool, however, has its limitations. This book carefully examines the limitations and assumptions associated with the application of the method to each of the domains discussed. Goal of this Dahlem Workshop: to evaluate the environmental and genetic mechanisms underlying the structure and development of behavior in twins studies: the achievements, limitations, and potentials.

The Oxford Handbook of Quantitative Methods in Psychology provides an accessible and comprehensive review of the current state-of-the-science and a one-stop source for learning and reviewing current best-practices in a quantitative methods across the social, behavioral, and educational sciences.

Few would dispute the truth of the statement `People are Different', but there is much controversy over why. This book authoritatively explains the methods used to understand human variation, and extends them far beyond the primary `nature or nurture' question. After chapters on basic statistics, biometrical genetics, matrix algebra and path analysis, there is a state-of-the-art account of how to fit genetic models using the LISREL package. The authors explain not only the assumptions of the twin method, but how to test them. The elementary model is expanded to cover sex limitation, sibling interaction, multivariate and longitudinal data, observer ratings, and twin-family studies. Throughout, the methods are illustrated by applications to diverse areas such as obesity, major depression, alcohol comsumption, delinquency, allergies, and common fears.

This book provides an overview of human and animal behavioral genetics and examines the crossroads where the fields of psychology, psychiatry, and genetics intersect.

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.

Along with psychopathology, cognition has been one of the primary phenotypic focal points of the field of behavior genetics since its inception. Francis Galton’s 1874 examination of eminent families in Britain was among the earliest attempts to investigate whether cognitive achievements run in families. This volume presents current methodologies for understanding cognitive abilities that move beyond the outdated nature vs. nurture paradigm. Recent advances in both collection and statistical modeling of twin data, particularly longitudinal twin data, make this an especially advantageous moment to produce a work that presents a collection of the groundbreaking research on cognitive abilities across the lifespan. This volume presents an overview of the current state of quantitative and molecular genetic investigations into the many facets of cognitive performance and functioning across the lifespan.​

* Brief, accessible overview of methods and findings of behavioral genetics written by a leading scholar in the field.

Wrestling with Behavioral Genetics brings together an interdisciplinary group of contributors -- geneticists, humanists, social scientists, lawyers, and journalists -- to discuss the ethical and social implications of behavioral genetics research. The essays give readers the necessary tools to critically analyze the findings of behavioral geneticists, explore competing interpretations of the ethical and social implications of those findings, and engage in a productive public conversation about them. "What sets this collection apart from others is the way that contributions from a diverse authorship are integrated to form a coherent whole... Doubtless this book will soon become a classic within behavioral genetics and compulsory reading for the non-specialist seeking to understand the basic scientific, social, and ethical issues within the field." -- American Journal of Bioethics "Informative, provocative, and challenging, this book is a must-read for anyone seeking to understand this emerging field." -- Social Theory and Practice "Promoting public conversation about behavioral genetics will be increasingly pertinent to creating enlightened, fair, and representative public policy... The 'wrestling' will go on for some time to come." -- New England Journal of Medicine "This volume presents a fair and honest treatment of the field that is both cautious at times and also optimistic and hopeful." -- Metapsychology Erik Parens is a senior research scholar at the Hastings Center and a visiting professor in the Science, Technology, and Society Program at Sarah Lawrence College. Audrey R. Chapman is a professor of community medicine and Healey Chair in Medical Humanities and Bioethics at the University of Connecticut School of Medicine. Nancy Press is a professor at the School of Nursing and the Department of Public Health at the School of Medicine, Oregon Health and Science University.

The identical “Jim twins” were raised in separate families and met for the first time at age thirty-nine, only to discover that they both suffered tension headaches, bit their fingernails, smoked Salems, enjoyed woodworking, and vacationed on the same Florida beach. This example of the potential power of genetics captured widespread media attention in 1979 and inspired the Minnesota Study of Twins Reared Apart. This landmark investigation into the nature-nurture debate shook the scientific community by demonstrating, across a number of traits, that twins reared separately are as alike as those raised together. As a postdoctoral fellow and then as assistant director of the Minnesota Study, Nancy L. Segal provides an eagerly anticipated overview of its scientific contributions and their effect on public consciousness. The study’s evidence of genetic influence on individual differences in traits such as personality (50%) and intelligence (70%) overturned conventional ideas about parenting and teaching. Treating children differently and nurturing their inherent talents suddenly seemed to be a fairer approach than treating them all the same. Findings of genetic influence on physiological characteristics such as cardiac and immunologic function have led to more targeted approaches to disease prevention and treatment. And indications of a stronger genetic influence on male than female homosexuality have furthered debate regarding sexual orientation.