Thesis: in child development, a theory is an organized set of ideas that is designed to explain and make predictions about development. Maturational theory: child development reflects a specific and prearranged scheme or plan within the body. In gesell"s view, development is simply a natural unfolding of a biological plan; experience matters little. Development would occur naturally without interference of adults. This was discarded because it didn"t touch on the impact environment has a child"s development. Ethological theory: views development from an evolutionary perspective. A critical period in development is the time when a specific type of learning can take place; before or after the critical period the same learning is difficult or even impossible. For example, chicks follow the first thing they see after birth. They are programmed to imprint on someone, usually a mother to create an emotional bond. The critical period for imprinting was only one day. Children"s genes influence virtually every aspect of their development.