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. In a study design that includes both identical and fraternal twins, a researcher can estimate the relative influence of genes and environments on behavioral differences among people.
Identical, or monozygotic, twinning occurs when one egg is fertilized by one sperm then splits after conception into two genetically identical halves. These twins share all of their genes and are the same sex. Fraternal, or dizygotic, twinning occurs when two eggs are released by the mother and fertilized by two separate sperm. Fraternal twins share on average half of their genes, just like typical siblings. They can be the same sex or opposite sex. About two-thirds of all twins are fraternal.
Summary This article discusses about twins separated and the genetic of personality differences and concentrated on studies that have been made in 1979 by the Minnesota Study of Twins Reared Apart (MISTRA). In this research, the researcher focused on two aspects of cognitive and personality. However, in this article the discussion limited to discuss about the personality and behavioral differences only. The study conducted by Minnesota is to support the existence of an important genetic component in behavioral and personality differences.
References: TWIN STUDIES http://social.jrank.org/pages/666/Twin-Studies.html Richard M.Ryckman , Theories of Personality, Ninth Edition. 2008, 2004 Thomson Wadsworth, a part of The Thomson Corporation