The Minnesota study of twins reared apart - Term Paper Example

This paper of the Minnesota Center for Twin and Adoption Research (MICTAR) published in 1990 was the culmination of research that had started in 1979. The study was an endeavour to probe human behavior and determine the factors(genes vs. environment) that affected and shaped us psychologically and to what extent. Thus ultimately the question it sought to answer was-'why are you what you are?' (Bouchard et al., 1990) and to determine the predominant factor-"Is it nature or nurture?" For this purpose the researchers compared (monozygotic) identical twins separated at birth and reared apart (MZA) and identical twins reared together(MZT).

Studying identical twins allowed researchers to identify both environment and genetic influences on child development and psychology as they share 100% DNA and are genetic clones of each other as they arose from a single zygote. Thus one can 'assume that those behavioral and personality characteristics they have in common as adults must be genetic.' (Bouchard et al., 1990) From 1983 onwards the researchers studied 56 pairs of MZA twins along with MZT twins individually. They compared the twins’ intelligence, personalities, aptitudes, family environment and more to find out which traits are mostly due to nature, and which are due to nurture.

The enormous volume of data collected was statistically processed and it was found that 'almost every behavioral trait so far investigated, an important fraction of the variation among people turns out to be associated with genetic variation.' (Bouchard et al., 1990) . He is credited for coining the term eugenics and is recognized as the Father of twin research. His first book Hereditary Genius, published in 1869, tried to prove that majority of humans' natural ability were inherited and his second book 'English Men of Science- Their Nature and Nurture' gave us the phrase which is now often used in the context of twin and family research.

In 1905 American psychologist E.L. Throndike first made use of psychological tests for his twin study published that year. Though the first classical twin study reported was that of Walter Jabonski in 1922 who studied the contribution of heredity to refraction in human eyes. But Hermann Siemens of Germany first proposed that the similarities of identical and fraternal twins can be utilized as a way to determine the role of genetic factors for diseases and traits. But unfortunately psychiatric genetic data was used by the Nazis against Jews to justify eugenic sterilization and murder and to test racist ideas.

Also post World War II the doctrine of behaviorism dominated psychological thought. Behaviorism credited environmental factors as stimuli which control human behavior, and as such rendered further scientific enquiry into human behavior unnecessary. Even the perception among laymen of that time was that experience and environment were the implements that sculpted human nature. Thus twin studies were widely discredited at that time partly because of poor experimental protocol, and partly because the leader in the field at that time Sir Cyril Burt (1883-1971) was found guilty by the British Psychological Society of fraud 5 years after his death for using false data, and inventing facts to support his