How to Explain Serial Killers Who Come from Good Homes

They say the apple doesn't fall far from the tree, and serial killers' psychological dysfunction often correlates strongly to a broken childhood home. According to psychologist Terence Leary, director of the Serial Killer Database Research Project, nearly all of them are raised in an abusive environment.

"What we're finding is a great, great preponderance of abuse amongst serial killers," Leary tells A&E Crime + Investigation, adding that his database contains information about more than 5,000 serial killers, and dates back to the 1950s. "In every case I've looked at… there's some kind of horrendous home situation."

But every rule has its exceptions. For all the killers with miserable pasts, there are also a select few whose biographies provide scant clues to the murderous impulses they would unleash later in life. What made these killers tick? We look at some of the killers whose seemingly normal childhoods gave way to unspeakable cruelty.

The sexual sadist who taunted police and journalists for decades with anonymous letters signed BTK—for his "Bind, Torture, Kill" murder method—was the most ostentatiously brutal serial killer that Wichita, Kansas had ever seen. He killed at least 10 people between 1974 and 1991, including four members of the same family (the Oteros). But when Dennis Rader was finally apprehended in 2005, the world was shocked by just how ordinary a life he had otherwise lived.

His father, Bill, was a plant operator for a utility company. According to Dennis's childhood friends, Bill Rader was strict, but not mean. Dennis Rader read comic books and dime store novels. He was well-liked.

As an adult, he started his own seemingly normal family, who had no clue about his secret life. His three brothers have all likewise led quiet, felony-free lives.

Adrian Raine, a neurocriminologist at the University of Pennsylvania, says violent offenders often seem to spring out of nowhere.

"I get letters every week from good parents, and you can see—the cause of the problem behavior in their psychopathic son is not the parenting," says Raine. "We all see it: two parents with three kids, and two of the kids are just like the parents. But with the other kid, you think, where did he come from?"

One of those "kids" grew up to be Richard Cottingham, a serial killer who targeted sex workers in the Times Square area of New York City between 1967 and 1980.

Although he is only officially known to have murdered 11 people, the "Butcher of Times Square" claimed in a 2009 interview that he killed more than 80 people before he was finally apprehended in 1980.

There was little from Cottingham's childhood that points to homicidal rage. Born in the Bronx, Cottingham's family moved to the suburban town of River Vale, New Jersey, when he was a young boy.

Historian Peter Vronsky, who is currently writing a biography on Cottingham and has spent more than 50 hours interviewing the prisoner, says he's uncovered nothing in the murderer's youth that points easily to a life of extreme violence.

His childhood was "absolutely idyllic," Vronsky says. "His father was [a]  vice president [at] Metropolitan Life Insurance in New York City. Three younger sisters who absolutely adored him—all well-adjusted, no reports of family dysfunction. A mom who was a homemaker housewife. Catholic parochial schools."

Vronsky said that over the course of several interviews he's asked Cottingham several times if he suffered any kind of abuse: sexual, psychological or otherwise. Cottingham, he says, always flatly refuses, and sometimes even jokes around by saying that Vronsky will have to make up a story of abuse at the hands of the priests who taught him.

One potential explanation, Vronsky says, is brain damage: Cottingham was hit by a car as a four year old and suffered brain damage to his frontal lobe—an area of the brain associated with the desire to commit acts of aggression.

Still, not all serial killers who come from good homes can put the blame on bad neurology. Some have well-functioning brains and backgrounds that point to life on the bell curve of normalcy. And yet...

Randy Kraft is one such example. Say Raine, "If you look at Randy's brain scan, you can see it's perfectly normal. He has good frontal lobe functioning."

In a darkly ironic twist, Raine says that Kraft's high brain functioning probably helped his efficacy as a killer. "Randy killed 64 people in a 12-year period," Raine says. (Sixteen of those were confirmed.) "To do that, you need to have something good going for you. He had a very good brain that allowed him to regulate his behavior."

Known as the "Scorecard Killer," for the detailed list of victims he kept in the trunk of his car, Kraft was only apprehended after being pulled over for a moving violation with a dead body in his passenger seat. And although his crimes were twisted, Kraft's past wasn't.

Raine profiles Kraft in his book, The Anatomy of Violence: The Biological Roots of Crime, in which he discusses at length the young man's trouble-free past: growing up in Orange County, California, where he would bowl with his father and eat strawberries and whipped cream with his mother. With an IQ of 129 (which is considered high), Kraft took accelerated classes in high school and attended Claremont Men’s College (now Claremont McKenna College), a top-tier liberal arts school.

A stable upbringing, Raine says, points to an uncomfortable truth: that part of what makes people psychopathic killers is biological, a fate written into one's chemical composition.

"Clearly, there's no question that genetic factors explain about 50 percent of the variation amongst us in terms of who is violent and who is not. That's beyond reasonable doubt. What we don't know yet is what specific genes are responsible," Raine says. "It's difficult to pinpoint the genes—but we know they exist. Trying to figure out which gene is responsible for the crime—it's a bit like trying to catch a serial killer, on the run."