Effect Of Heredity And Environment

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Effects of Heredity and Environment
on individual Differences
Most psychologists acknowledge that both heredity and environment are influential; the argument is over which factor is predominant
The nature-nurture issue first became a controversy in the 1920's and the 1930's. Some psychologists felt that heredity was the primary, if not the sole, factor in the development of an individual. Others felt environment was the critical determining factor. As we saw in Unit One, this controversy is still unresolved. Still, most psychologists agree that some degree of interaction between heredity (nature) and environment (nurture) determines both physical and psychological development. In this module we will consider the relation of both factors to intelligence and behavior disorder.
As you read the text, consider the following questions.
• Has heredity or environment made the greater contribution to your development?
• Are there any upper or lower limits of intellectual achievement?
• What research methods are used in heredity-environment studies?
The interaction between heredity and environment can be studied by investigating families and persons who are related in various ways. Hereditary similarity is relatively well understood. A parent and child, for example, have 50% of their genes in common, but among siblings this may vary from 0 to 100% due to the random distribution of chromosomes. Identical twins have the same heredity; 100% of their chromosomes are alike.
Environmental differences cannot be stated in such concrete terms. No two persons experience an identical environment. Very similar environments are usually experienced by same-sexed twins, whether identical or fraternal. Different-sexed twins, siblings, and parents all experience somewhat different environments, although these environments may be superficially similar. Occasionally, identical twins are reared apart. Then we have two people with identical here...