How people become criminals is a matter of speculation and theory. There is no one explanation on why a person partakes in criminal activity and no tests that can conclude which people will eventually develop into criminals. However, many of the theories about the criminal mind are based on extensive research and analytical data that has been compiled by experts in the field of criminology.
The first types of theories behind how a person becomes a criminal comes from an environmental standpoint. Social ecology became a popular theory behind criminal activity in the 1950's. Studies have shown that crime rates are higher in areas stricken by poverty, disorder, and community deterioration. Strain theory, as described by Robert Merton, suggests that if the social structure of opportunities is unequal and prevents the majority from realizing the "American Dream", some will then turn to illegal activity to achieve it. Other's will become deviants.
Other theories are considered Individual theories, which are based on the individual person as a whole. Criminologist Lonnie Athens developed a theory about how domestic and societal violence in childhood can cause a person to become a criminal as an adult. Along these same lines are the new theories as to whether playing violent video games or watching explicit television programs can trigger violent criminal behavior or not.
A theory that is becoming more popular among criminologists and other researchers is the possibility of there being a malfunction in the way the brain of criminal processes information. This can be due to mental illnesses or certain types of seizure disorders. EEGs have been run on criminals to study how their brains react to certain stimuli as compared to the brains of those who are not criminals.
Criminologist, Ray Jeffery believes we should go a more scientific route and employ public-health techniques to treat criminals. He states, "What we need is a modern crime-prevention model, one that uses science to determine the causes of criminal activity-including the chemical, psychological, dietary and environmental causes." However, the idea that people become criminal due to disease is not entirely new. Gandhi himself is quoted as having said, "All crime is a kind of cancer and should be treated as such."
I think most people in the public can agree that a criminal is most likely created by a mixture of theories both individually and environmentally. Not all criminals had an abusive childhood. Not all children who play video games will grow up to be killers and rob convenient stores. Not everyone with a mental illness will be a serial killer. There is no way to tell who will become a criminal and what type of crime they will commit. Personally, I believe, that having a strong sense of morals and values can help prevent the urge to go against the laws of society even when the odds are stacked against you.