8/7/2026
Recently I read an introduction to Criminal Behavior: A Psychological Approach, one of the classic textbooks in criminal and forensic psychology. First published in 1991 by Anne M. Bartol and Curt R. Bartol, it has been revised through 12 editions and has been widely used for decades in university courses on criminology, psychology, criminal justice, and forensic science.
What makes the book influential is its psychological approach to crime. Drawing on research from psychology, psychiatry, neuroscience, sociology, biology, and criminology, it explores questions such as why some people become violent, how personality and early life shape behavior, and how biological and environmental factors interact. It also discusses topics including psychopathy, juvenile delinquency, violent crime, sexual offending, mental illness, and offender rehabilitation.
What interests me most is what this research teaches us about human nature. Understanding why some people commit crimes helps us better protect ourselves and our children, while also giving us a deeper understanding of human behavior.
One question I had before reading about the book was: Are some people born evil?
The answer, according to modern psychology, is no. There are no absolute "born criminals." Some people are born with biological traits that increase their risk of criminal behavior—such as greater impulsivity, lower empathy, heightened aggression, or a stronger tendency toward risk-taking. These are risk factors, not destiny.
One well-known psychological framework is the Dark Triad, a combination of three personality traits associated with a greater likelihood of manipulative and antisocial behavior.
The first is Machiavellianism—a tendency to manipulate others for personal gain with little regard for morality and others.
The second is pathological narcissism—an exaggerated sense of self-importance coupled with intense anger when one's inflated self-image is threatened.
The third is psychopathy, characterized by having no feeling, lack of empathy and remorse, and a willingness to exploit others.
Yet possessing these traits does not inevitably lead to criminal behavior. Many people with some of these characteristics function successfully within society and never commit crimes.
That brings us to another important idea:
Genetics loads the gun, but the environment pulls the trigger.
Genes may create vulnerabilities, but whether those vulnerabilities develop into criminal behavior depends greatly on life experiences. A warm, supportive family, positive role models, and healthy social environments can become powerful protective factors.
Extensive research shows that many adult offenders experienced childhood adversity, including neglect, abuse, chronic family conflict, or parental absence. Such experiences do not guarantee criminal behavior, but they can significantly increase the risk.
A Chinese saying captures the role of external circumstances in shaping aggressive behavior: 兔子急了咬人 (Tùzi jí le yǎo rén), meaning that even a gentle rabbit will bite when cornered or pushed beyond its limits. This suggests that aggression or violence can arise from circumstances, not just innate disposition.
Another finding surprised me. In homicide cases, victims are often killed not by strangers but by people they know—family members, intimate partners, friends, acquaintances, or colleagues. The greatest danger frequently comes from within one's social circle rather than from an unknown assailant.
The motives for homicide are varied, including domestic conflict, jealousy, financial disputes, revenge, sexual violence, and, more rarely, thrill-seeking. While the specific motives differ, many murders arise from conflicts that gradually escalate rather than from random encounters.
This changes the way we think about personal safety. Staying indoors after dark or installing stronger locks certainly has its value, but safety also depends on recognizing warning signs in the people around us. Sometimes the greatest protection comes not from securing our homes against strangers, but from learning to recognize unhealthy, manipulative, or violent relationships before they turn dangerous.
My biggest takeaway from this book is that understanding crime is ultimately about understanding people. The better we understand human nature—both its strengths and its vulnerabilities—the better equipped we are to protect ourselves, raise our children wisely, and build healthier relationships.
