Like constructing a house, brains are built upon a strong foundation. This starts before birth, and is very important during the first three years of life. Brain cells are “raw” materials — much like lumber is a raw material in building a house, and a child’s experiences and interactions help build the structure, put in the wiring, and paint the walls. Heredity (nature) determines the basic number of “neurons” (brain nerve cells) children are born with, and their initial arrangement