ARTICLE REVIEW
Separated Twins and the Genetics of Personality Differences: A Critique
Author(s): Jay Joseph

EDP 1002 : THEORIES OF PERSONALITIES

Introduction
Throughout history, across all cultures, people have been fascinated with twins. In addition to interest in the close emotional ties and biological similarities that twins may share, reports of special twin languages and twin extrasensory perception (ESP) help people to explore ideas of what it means to be human. How similar or different are they to each other? How important are genes and environment for development? Because identical twins share all of their genes, it is the environment—rather than genetics—that accounts for any differences between them.
As a result, researchers have found that the degree of MISTRA comparable personality similarities between reared apart and reared-together twins shows that a normal family environmental factors had no significant influence on adult personality. The 50% of the environmental variance appears due mainly to unusual environmental factors and measurement error.
The Theories Involved
This article discussed about studies of separated twins which is under Biological Underpinning of Personality Theories. It is mainly about genes and personality. A study of separated twins is both a twin study and an adoption study as one or both twins have been took away from their biological mother and then they are placed into their foster family. This article emphasizes on the Minnesota Study of Twins Reared Apart (MISTRA), a project that was conceived in 1979. This project was aims to determine whether the genetic influence on the behavior and personality of monozygotic twins that were reared-apart. So, it can be seen that this article is mainly focuses on twin studies, adoption studies as well as non-shared environment. Jim Lewis and Jim Springer (commonly called the “Jim Twins”) were the first pair of MISTRA separated twins. Through MISTRA, it was revealed that both monozygotic, or identical, twins reared apart (MZA) and monozygotic, or identical, twins reared together (MZT) correlate at about .50 on personality tests. Thus, it leads to the conclusion that
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