Is behavior learned? It is inborn? What of aggression, intelligence, and madness? There is a crucial relationship between the behavior of humans toward their own kind and the view of life they hold. Interest in behavioral genetics depends on wanting to know why people differ. According to Jack R. Vale, in Genes, Environment, and Behavior, recognition of the importance of hereditary influence on behavior represents one of the most dramatic changes in the social and behavioral sciences during the past two decades. A shift began toward the more balanced contemporary view that recognizes genetic as well as environmental influences on behavior. Behavioral genetics lies in its theory and methods, which consider both genetic and environmental sources of behavioral differences among individuals. Behavioral genetics is simply the intersection between genetics and the behavioral sciences.
Behavior is a phenotype that is, an observable characteristic we can measure. On the other hand, behavior is not just another phenotype. According to Robert Plomin in Behavioral Genetics, “Because behavior involves the action of the whole organism rather than the action of a single molecule, a single cell, or a single organ, behavior is the most complex phenomenon that can be studied genetically. Unlike some physical characteristics, behavior is dynamic, changing in response to the environment indeed, behavior is at the cutting edge of evolution text, because its focus is on the complexity of behavioral phenotypes”(2).
Obviously, there can be no behavior without both an organism and an environment. For a particular behavior, what causes differences among individuals? For example, what causes individual differences in cognitive ability? Various environmental hypotheses can leap to mind: Families differ in the stimulation they offer for cognitive growth; environments differ in motivating people toward intellectual goals; educational experiences differ. However, genetic hypotheses should also be considered. Research in behavioral genetics is directed toward understanding differences in behavior. Methods are employed that consider both genetics and environmental influences, rather than assuming that one or the other is solely important. Behavioral genetics research studies whether individual behavioral differences are influenced by hereditary differences. Then, estimates the relative influences of genetic and environmental factors. Although genetic and environmental influences interact within an individual, this does not imply that the separate effects of genes and environment cannot be untangled when we focus on differences among individuals
Controversy arises when nature (inheritance) is combated against nurture (environment). This controversy began with the development of the behavioristic point of view. “Behaviorism arose as a protest against all form of “introspective psychology,” which was concerned with mental states...