Biological positivism is a theory or approach that takes an individual's characteristics and behavior that make up their genetic disposition is what causes them to be criminals.
Historically, medicine became interested in the problem of crime, producing studies of physiognomy (see Johann Kaspar Lavater and Franz Joseph Gall) and the science of phrenology which linked attributes of the mind to the shape of the brain as revealed through the skull.
William Sheldon identified three basic body or somatotypes (i.e. endomorphs, mesomorphs, and ectomorphs), and introduced a scale to measure where each individual was placed.
[citation needed] The excessive consumption of alcohol can lower blood sugar levels and lead to aggressiveness, and the use of chemicals in foods and drinks has been associated with hyper-activity and some criminal behaviour.
Sigmund Freud divided the personality into the id, the primitive biological drives, the superego, the internalised values, and the ego, memory, perception, and cognition.
This has been discounted in favour of general privation (Michael Rutter: 1981) or "broken homes" (Glueck: 1950) in which absentee or uncaring parents tend to produce badly behaved children.
Hans Eysenck (1987) stated that, "…certain types of personality may be more prone to react with anti-social or criminal behaviour to environmental factors of one kind or another."
In general terms, positivism rejected the Classical Theory's reliance on free will and sought to identify positive causes that determined the propensity for criminal behaviour.
Hence, environmental criminology and other sub-schools study the spatial distribution of crimes and offenders (see Adolphe Quetelet, who discovered that crimes rates are relatively constant, and the Chicago School which, under the leadership of Robert E. Park, viewed the city as a form of superorganism, zoned into areas engaged in a continuous process of invasion, dominance, and succession).