Final answer:
To determine the genetic component of traits, identical twins are compared with fraternal twins, revealing strong genetic influences on personality. However, epigenetics highlights the role of the environment in expressing different phenotypes from the same genotype.
Step-by-step explanation:
One common way to determine how much of a trait is due to genetic influence is to compare identical twins with fraternal twins. These comparisons help scientists understand how traits can be shaped by genetic makeup versus our social environment. Studies like the Minnesota Study of Twins Reared Apart have shown that identical twins exhibit a high degree of similarity in traits such as personality, indicating a strong genetic component. However, there's a complex interaction between our genes and our environment, as seen in epigenetics, where the same genotype can result in different phenotypes because of different environmental influences. For example, identical twins may have the same genotype but can express different traits or susceptibilities to diseases like cancer due to the variations in their environments.