The biosocial theory states that all of the violent street crimes, such as rape, murder, and assault, are committed by poor and minority-group members. These people, as stated by this theory, are somehow biologically different and inferior. This theory was founded by Cesare Lombroso (1835-1909), otherwise known as the "father of criminology". He was a physician, who studied the physical characteristics of Italian soldiers who were convicted of criminal offenses and inmates at institutions for the criminally insane. His studies led him to believe that serious offenders, or those who engage in repeated criminal activity, have inherited criminal traits, which compel them to commit crimes repeatedly. As well, he believed that these criminals had atavistic anomalies, meaning that they were physically akin to the primitive "savages" of early society. According to him, these criminals supposedly have enormous jaws and strong canine teeth, much like the prehistoric people that they stem from. His conclusion was that people with these criminological traits had a degenerate family gene, causing frequent cases of insanity, epilepsy, and alcoholism among family members, and crime from being directly linked with one of these families.
The biosocial theory stemmed from Lombroso, but does not entirely embody his beliefs. Most biosocial theorists today believe that people carry the potential to be violent and antisocial, and depending on their environmental situation, they can show these antisocial qualities at any time if the conditions for it are right. This can help explain why certain people who have abided the law their whole lives can suddenly turn violent, and people who have been criminals all their lives can turn to a more conventional lifestyle. As well, this theory helps explain the belief behind geographical and temporal patterns in the crime rate. For example, people in hot summer climates are more likely to have their environment influencing them to commit violent crimes than people in cold winter climates. To biosocialists, behavior is both a product of interacting biological and environmental events.
This theory of behavior has many criticisms, the main one being that the biosocial theory has a lack of empirical testing and evidence to back it up. For example, most research groups have had small, nonrepresentative sample sizes. Also, most research regarding this theory has been done on offenders who have been placed in clinical treatment settings, making it impossible to tell if the findings of this theory are only based on convicted criminals put into correctional facilities, or the whole criminal population.