Being a Biology major, I found the epigenetic theory really interesting to learn about. It’s amazing how as scientists, we are always learning new things; being able to study the interaction between genes and the environment. Erik Erikson is most famous for his work in refining and expanding Freud's theory of stages. Development, he says, functions by the epigenetic principle. This principle says that we develop through a predetermined unfolding of our personalities in eight stages. Our progress through each stage is in part determined by our success, or lack of success, in all the previous stages. A little like the unfolding of a rose bud, each petal opens up at a certain time, in a certain order, which nature, through its genetics, has determined. If we interfere in the natural order of development by pulling a petal forward prematurely or out of order, we ruin the development of the entire flower.

Each stage involves certain developmental tasks that are psychosocial in nature. Although he follows Freudian tradition by calling them crises, they are more drawn out and less specific than that term implies. The child in grammar school, for example, has to learn to be industrious during that period of his or her life, and that industriousness is learned through the complex social interactions of school and family.