What happens to the development of feral children who are raised without significant social contact? What does this demonstrate about the importance of socialization?

The text cites the case of Genie, who was sequestered by her father in her family's California home. Genie did not learn to speak and communicated by making low croaking sounds. When the authorities finally discovered her, it was found that, in almost all ways, Genie had failed to develop as a normal child. Her behavior could only be described as primitive and bizarre, although there was never evidence that she had a physical or mental disability.
It took years for her to acquire language and learn to interact with others. This case demonstrates that without socialization, we are almost totally devoid of the qualities that are normally associated with being human.