This paper discusses the development of species-identity in humans, emphasizing the influence of environment vs. heredity. The cases of two feral children, and three children raised with limited human contact are presented and research concerning institutional upbringing is discussed. These reports all imply or state that reduced contacts with humans will lead to long term disruption of social and affiliative behaviors. Different theoretical positions on human development are surveyed. It is concluded that species-identity in humans is primarily environmentally determined. Ramifications of this statement are suggested. (SB)