Her only human contact was with her father, Clark Wiley, who beat her every time she vocalized, and barked at her like a dog to quiet her. By the time Genie was liberated in 1970, she was nearly mute, uttering only a handful of phrases, including "stop it" and "no more."
The girl was known for her "bunny walk," because she held her hands like paws, and her social interaction was limited to sniffing, spitting and clawing.
At 53, Genie is still alive and living in a California group home. She never grasped complex language.
According to psychiatric experts, children who are raised in isolation, in addition to their health problems, struggle with attachments to others, language development and the capacity for impulse control and self regulation.
Men who repeatedly molest their children are not only pedophiles but psychopaths, according to Dr. Igor Galynker, Associate Director of Psychiatry at Beth Israel Medical Center in New York City.
In a paper he co-wrote with psychologist Lisa J. Cohen, he compares pedophiles to opium addicts, "only they are much sicker."
Repeat pedophiles are psychopaths, according to Galynker, because they repeatedly break the law.
"A psychopath is somebody who perpetrates a crime and breaks the law internally," he said. "They perceive victims as tools and lack empathy and a conscience."
A high number of pedophiles report that they were also abused as children, but not all go on to victimize children, said Galynker.
His studies have also shown that these types of men are "odd and bizarre" people, loners who are disconnected from others with a "twisted logic" that helps them justify their behavior.
"In the real world, they would be in jail where they are probably murdered, because they don't like pedophiles," said Galynker. "If they end up in the psychiatric hospital, they can be treated, but it's not that effective."
Fritzl said last year while awaiting trial that he wants doctors to use him as a "guinea pig," to learn more why he treated his daughter like a sex slave.
"I may be in prison for a while, and I would like to offer myself to as many of the world's best profilers, psychologists and psychiatrists as possible," he told the Austrian Times. "I realize now that I am not normal, and I see that somebody who did what I did cannot be regarded as normal.
a clinical psychologist who specializes in issues of fatherhood and masculinity at the University of Akron in Ohio, said men capable of these heinous crimes have often been forced to conform to rigid standards of masculinity in their childhood.
"[They are] boys who are beat up for crying or made to feel ashamed of themselves when they show fear or have the inability to identify their own emotions," he said.
In a disorder Levant calls normative male alexithymia -- difficulty processing and understanding emotional experiences -- men often numb themselves with alcohol or violent behavior.
"People think masculinity comes with the Y chromosome but some psychologists think masculinity is a set of norms that little boys are pressured into conforming to," said Levant.
"The inability to experience their own emotion makes it hard for them to empathize with another person," he said. "These guys can do horrible things."