Contemporary researchers believe that both hereditary and environment are involved in every aspect of a child’s development (Berk, 2012, pg. 82). Physical aspects, such as the color of a child’s eyes or hair, and even behavioral similarities such as a child being outgoing or shy, are frequently the responsibility of genetics. Even so, while our observable characteristics are apart of our hereditary makeup, these aspects will constantly be affected by a lifelong history of personal experiences (Berk, 2012). A set of identical twins growing up in the same house will share 100% of the same genetic makeup (Barry, 2012). Any differences between the identical twins must be due to environmental factors, since their genetic endowment is exactly the same (Barry, 2012). Even though the twins share 100% of the same genes, their change over time will be the responsibility of each child’s biologically influenced dispositions along with each of their personal environmental contexts (Berk, 2012). The identical twins will share much of the same environment, and their shared environment can be explained by using Urie Bronfenbrenner’s Ecological Systems Theory, which views the child as developing within a complex system of relationships affected by multiple levels of the surrounding environment (Berk, 2012 pg. 26). Using Bronfenbrenner’s model, we will find that aspects making up the microsystem and mesosystem are a shared environment for the twins and even non-shared influences, that will