As is true of other problem behaviors, criminal behavior is caused by a combination of environmental, psychological, and biological factors. "If you chose ten kids at random, it wouldn't be difficult to pick the ones who are at risk of becoming criminals. It's not magic. There are certain symptoms like short attention span, lack of impulse control, and poor home life that are likely predictors of criminal behavior," says Larry Siegel, professor of Criminal Justice at the University of Lowell in Massachusetts, and co-author of a popular college textbook on criminology.

The Testosterone Factor

Most crimes are committed by young men in their teens and twenties, a pattern that exists in societies from Britain to Burma. The reason for this phenomenon is clear: testosterone. This hormone, which is responsible for male physical characteristics and behavior traits such as aggression and impulsivity, floods the bodies of adolescent boys.

As a result, some boys go through an adolescent delinquent period, although most do not go on to pursue a life of crime. "A teenage boy will commit a crime at 15 that he wouldn't dream of doing at 25. If we can keep him out of prison, he may grow out of it," reports Jack Levin, professor of sociology and criminology at Northeastern University in Boston, Massachusetts, and director of the Program for the Study of Violence. Those who do become criminals are influenced by other factors, like psychological qualities.

Researchers P.T. Loosen, S.E. Purdon, and S.N. Pavlou of Vanderbilt University performed significant research to clarify the role of testosterone in aggression and violent behaviors. The idea was to observe what behavioral changes are associated with the mild reduction of testosterone versus total suppression of testosterone. What was clearly seen was an impressive decrease in “outward directed anger."

Common Criminal

One common type of career criminal is the classic sociopath (formerly known as psychopath). This well-known character disorder is characterized by a lack of conscience, inability to empathize with victims, manipulative behavior, and pathological lying. According to the American Psychological Association, 3% of American males are sociopaths, which literally equals millions of men. One prominent example, according to Levin, is Charles Stuart, the notorious Boston businessman who murdered his wife and initially convinced police that a black man was responsible. His reason for killing was typical of sociopathic behavior: his wife was an obstacle to his success.

There's no clear explanation of where sociopathy comes from, says Levin. One theory is that it's inborn, the result of "faulty wiring" or a "bad seed." Some psychologists, on the other hand, believe that this disorder results from a profound disturbance in early childhood, in which a little boy fails to bond with his parents and doesn't develop the capacity for warmth and caring.

Our prisons are filled with sociopaths, reports Levin, most of whom come from impoverished backgrounds. The sociopaths who manage to stay out of jail are usually from a higher social strata or have become wealthy from their illicit pursuits.

Disadvantaged Beginnings

Socioeconomic status is a huge factor in criminal behavior. The highest crime rates are in poor neighborhoods, which is a phenomenon sociologists call "innovation." People without the means to advance in a culture that highly values material success "innovate" through illegal means. Money is always a major motivating factor in crime, and during economically troubled times, crime rates always rise.

Most criminals come from low-income families, says criminologist Siegel. They generally have other strikes against them as well, such as poor attention span or ]]>attention-deficit hyperactivity disorder]]> (ADHD), impulsivity, learning disorders, an aggressive personality structure, health problems, and a dysfunctional family.

A child with the same problems who grows up in a more affluent community is not nearly as likely to become a criminal. "There are clear reasons why one kid gets a full scholarship to MIT and another gets a full scholarship to Walpole [a major Massachusetts prison]," says Siegel. The critical difference seems to be that middle- and upper-class communities have greater school and community resources. Without that support, a low-income child can become frustrated in school and believe that he has no legitimate means to succeed.

These children are easy prey for the neighborhood drug dealer, who may be the only adult who takes an interest in them. "He gets instant gratification, lots of money, and the chance to serve as an apprentice in a 'career'," says Levin. His new lifestyle includes joining a gang and carrying a gun. "Like other teens, he doesn't think of consequences, like jail. He's likely to become a career criminal," says Levin.

Popular Myths

Poverty may be a factor in crime, but the idea that most poor people exhibit criminal-like behavior is a myth. While there are an estimated 33 million Americans living in poverty, according to Siegel, there are only about two million criminals. So even if all criminals were poor (which they obviously are not), the percentage would be minuscule.

A study headed by L. Rowell Huesmann reviewed the association between watching TV shows with violent content at ages 6-10 and having aggressive behavior in adulthood. The study shows that identifying with violent heroes and watching adult violence that is perceived as real are predictors of later aggression. Siegel, though, discounts the argument that TV and movie violence incite violent behavior.

Another popular myth is that there is a "crime gene." Levin reports that there is no evidence for this, although there may be a genetic predisposition to aggression or lack of self-control.

The Violent Criminal

Violent criminals have generally suffered some form of abuse as children—neglect, abandonment, sexual and/or physical abuse, says Levin. Recent research does suggest that some violent criminals experience a combination of repeated ]]>head trauma]]> and abuse as children.

These children grow up with a profound sense of powerlessness and, therefore, overcompensate as adults by developing an excessive need for dominance, control, and power.

This need is the basis for sadistic crimes. Rapists and serial killers enjoy physical contact with their victims and triumph in their suffering. It makes them feel important and good about themselves, which they apparently can't feel in any other way. Similar motives underlie the current state of "thrill," hate, and revenge crimes, like the shootings by teenagers at public schools. Sadly, committing these crimes gives young people, who otherwise feel powerless, hope for the future.

Ultimately, the antidote to crime is providing young people with healthy alternatives, says Levin. "When kids feel good about themselves and gain a sense of importance and hope for the future, they do the right thing."