Compare Contrast Essay Identical Twins
Even today, the sole sculptor of human personality, behavior, and psychopathology remains unknown; modern research indicates that a combination of biology and environment constructs us all.
Studying how genes and our surroundings may or may not form the personalities, behaviors, and psychopathologies of human beings is probably the most obvious way to approach the argument of heredity versus the environment.
Twin studies, in general, assume that only one type of genetic mechanism--usually additive--is operating for a particular trait.
Methods and theory The classical twin study design relies on studying twins raised in the same family environments.
Monozygotic (identical) twins share all of their genes, while dizygotic (fraternal) twins share only about 50 percent of them.
So, if a researcher compares the similarity between sets of identical twins to the similarity between sets of fraternal twins for a particular trait, then any excess likeness between the identical twins should be due to genes rather than environment.
Researchers use this method, and variations on it, to estimate the heritability of traits: The percentage of variance in a population due to genes.