Final answer:
Environmental factors contribute to making identical twins more different by influencing the expression of their genotypes. The environment interacts with genetics, shaping individual traits and phenotypes based on different life circumstances and experiences.
Step-by-step explanation:
Studies on twins, particularly those that are identical, help us understand the impact of the environment on individuals. When identical twins are raised in different environments, they can exhibit differences that offer insights into the role of environment in shaping one's phenotype. Environmental factors can lead to different expressions of the same genotype, resulting in variability of characteristics, even among individuals with the identical genetic makeup. This variance is rooted in the concept of epigenetics, where identical genotypes can be expressed differently according to various environmental contexts. The Minnesota Study of Twins Reared Apart suggests that identical twins may have similar personalities, indicating a strong genetic component to certain traits. However, environmental influences and genetic environmental correlation show that such traits are not solely determined by genetics, but are also shaped by environmental factors.
In summary, the environment tends to make twins more different by influencing the different expressions of their identical genotypes. This takes into account not just the physical traits, but also personality traits and susceptibilities to certain conditions. Therefore, the answer is that environmental influences tend to make twins more different in various aspects, including their susceptibility to diseases and behaviors, despite having identical genetic material.