Studies have shown that the criminal tendency in a person has close links to his or her biological construction. Charles Darwin, one of the pioneers of the scientific study of crime, argues that the humans and animals are essentially related.

According to him, though humans are more developed than animals, the differences are only in matters of ‘degree’. His theories led to several scientific studies of criminal behavior. Besides Charles Darvin, some other pioneers in this field are Ennest Kretschmer, William Scheldon, Cesare Lombroso and Eleanor Gluck.

Ceasro Lombroso believed that criminality can be transmitted genetically across the generation. William Scheldon and Ernest Kretschmer argued that there was a specific relationship between criminal behavior and body type. William Sheldon divided the body types into three i.e. ‘endomorphic’ (fat and soft), ‘ectomorphic’ (thin and weak) and ‘mesomorphic’ (muscular and toned) and held that there is a relationship between body type and criminal tendency in a person.

Later on studies of Sheldon Glueck and Eleanor have proved that 60 per cent of offenders belong to mesomorphic type.

Now days, many people believe that, biological factors significantly influence the criminal tendency in a person. Biological factors such as genetic influences, chemical influences and neurological defects play a crucial role in motivating criminal activities.

In modern times, most of the efforts to fight criminal activities are based on sociological approaches; but these approaches have not been very successful because “they fail to acknowledge that many criminals suffer from brain malfunctions which prevent them from benefiting from sociological or psychological interventions.

Research shows that chronic offenders exhibit brain dysfunction leading to extreme "dyslogic." (Crime Times: Linking Brain Dysfunction to Disordered/Criminal/Psychopathic Behaviour). Some of the basic elements of the anti-social behavior are impulsivity, low tolerance, the absence of guilt and shame, imperviousness to learning through punishment and dysfunction.

Such behaviors have a biological basis, and in pressure situations, they tend to interpret other people’s behavior as threatening, provocative, and mocking. It has been proved that several criminals suffer from an array of cognitive deficits. These differences can be divided into four categories such as intelligence, moral development, learning disabilities and reasoning. Studies have also proved that people with lower IQ have greater affinity for crimes. Generally, the criminal’s mean IQ is, at least 10 point lower than non criminals group.

There is a possibility that low frustration tolerance, learning disability, poor verbal skills, inability to experience empathy might increase criminal behavior. It is also believed that “there is a relationship between crime and low serotomin metabolism in offenders” (Brownlee, Christen. Biology and crime). When the level of Testosterone, the male sex hormone, increases, the males tend to become aggressive.

List of Biological problems or anomalies of the patient

The patient, who is an 18 years old, is depressed. There is a sudden change in his personality and he becomes an extrovert. Now the question to be answered is that what are its consequences? Some of the consequences are listed below.