But what about the kids who aren't abused? What about the ones who, for no discernible reason, do horrible things to other people?
"I've always said that Michael will grow up to be either a Nobel Prize winner or a serial killer," his mother, Anne, tells Jennifer Kahn in a recent shocking New York Times Magazine article. At age 9, her son has an extreme temper, lashing out violently and deliberately and showing no empathy or remorse. He's intelligent, cold, calculating, and explosive. "It takes a toll," she says, explaining her comment. "There's not a lot of joy and happiness in raising Michael."
Experts are divided about whether it's right to label a child as a psychopath. On the one hand, their brains are still developing; since psychopathy is largely considered untreatable, such a label would carry a heavy, life-altering stigma. On the other hand, identifying "callous-unemotional" children early could allow for successful treatment -- or at least a heads-up to society.
But reaching such a diagnosis can be tricky. Certain tendencies, like narcissism and impulsiveness, that are obvious signs of a psychopath are also part and parcel of childhood. And callous-unemotional kids are often extremely intelligent; they're able to lie and manipulate without remorse, making it harder to understand what they're doing and why. "They don't care if someone is mad at them," Paul Frick, a psychologist at the University of New Orleans, told the New York Times. "They don't care if they hurt someone's feelings."
"If they can get what they want without being cruel, that's often easier," adds Frick, who has spent 20 years studying risk factors for psychopathy in children. "But at the end of the day, they'll do whatever works best."
The New York Times article mentions the case of 9-year-old Jeffrey Bailey Jr., who in 1986 pushed a 3-year-old into the deep end of a Florida swimming pool and then pulled up a chair to watch the child drown; after the toddler died, Bailey got up and went home. It's a disturbing crime -- and there are other equally disturbing cases of young kids committing cold-blooded murder.
- In 1993, Jon Venables and Robert Thompson, both 10 years old, took 2-year-old James Bulger by the hand and led the trusting toddler out of a shopping mall in Liverpool, England. Once away from the mall, they spent hours torturing him before beating him to death, reports said.
- In 1998, Joshua Phillips' mother was cleaning his room when she discovered the dead body of their 8-year-old neighbor, Maddie Clifton, under his bed. The 14-year-old Phillips says he accidentally hit the girl in the eye with a baseball bat and then panicked when she screamed, so he took her to his room and beat and then stabbed her until she stopped.
- Alyssa Bustamente was 15 when she confessed to luring her 9-year-old neighbor Elizabeth Olten into a nearby forest and killing her in 2009. "I strangled them and slit their throat and stabbed them now they're dead," Bustamante wrote in her diary at the time. "It was ahmazing. As soon as you get over the 'ohmygawd I can't do this' feeling, it's pretty enjoyable. I'm kinda nervous and shaky though right now. Kay, I gotta go to church now...lol." In February, she was sentenced to life in prison.
- Eric Harris -- who, with his friend Dylan Klebold, killed 13 people and injured 24 others when they opened fire at Columbine High School in Colorado in 1999 -- had several of the hallmarks of being a psychopath. As ABC News points out, he was described as "controlling, manipulative, and sadistic, but very much in touch with reality."
It's not as if these kids simply lack a moral compass. In Child of Rage, 6-year-old Beth opens her blue eyes wide and calmly tells her psychiatrist how she'd like to hurt, and even kill, her adoptive parents -- a Methodist preacher and his wife -- and her biological brother. She's calm and conversational as she describes how she has deliberately harmed and killed animals, how she drives pins into her brother and sexually molests him, how she repeatedly slammed his head into a cement floor and only stopped because someone caught her.
Beth suffered extreme physical and sexual abuse and neglect by her biological parents, which experts say could explain her detached, calculating demeanor and her lack of "a sense of conscience." (She now claims that she was "healed" by the time she was 7 or 8, thanks to intensive therapy.) But Michael, in the New York Times Magazine article, seems to have grown up surrounded by love and affection.
So if nurture (or a lack of it) isn't the only way a person becomes a psychopath, how much does nature have to do with it? Some experts say that psychopathy, like other mental illnesses, may have a genetic component; others think that it is a neurological condition all its own, like autism is, though it's not part of the autism spectrum. Though some psychologists believe one can start seeing psychopathic traits as early as age 5, there is not yet a definitive test for children that young.
"You're not born a psychopath but the foundation is there," Robert Hare, a professor emeritus of psychology at the University of British Columbia and author of Without Conscience: The Disturbing World of the Psychopaths Among Us, told MSNBC. He has developed specialized checklists to determine whether people age 12 and older show psychopathic tendencies. "We're all born with temperaments that can be shaped by the environment."
What do you think? Can a young, seemingly innocent child be a psychopath -- and are they just born that way?