- Lombroso (1876) believed that ‘throwback’ characteristics, coded for by a single defective gene, contribute to the atavistic (primitive) form: a different species of distinct physical characteristics such as thicker eyebrows and higher cheekbones. As well as different physical features, these people had criminal behaviour.
No single gene has been found to cause criminal behaviour or to contribute to common criminal characteristics. Though Lombroso’s work lacked control groups and included people with psychological and physical disorders, he shifted the study of crime to a more empirical basis. He later believed, after proposing the atavistic form, that crime actually occurred due to environmental factors. This gave rise to the line of though that biological and environmental factors together result in criminal behaviours.
- Sheldon‘s somatotype theory (1949) states that criminality is linked to temperament, which is a result of their constitution. Ectomorphs, tall and skinny, are solitary and restrained. Endomorphs, short and round, are relaxed and hedonistic. And mesomorphs, those believed to possess the ‘criminal build’, are hard and muscular, energetic and adventurous.
Sheldon rated thousands of photographs of college students and delinquents, and found that delinquents had a higher mesomorph rating. Though a large data set was used, the subjective scale and large experimenter bias concludes this study as invalid. Sheldon also did not use legal criteria, but when it was used, it was found that an association between criminal activity and constitution was not present (Sutherland 1951). Similarly, Putwain and Sammons (2002) criticised the approach as it rests on the stereotyping and labelling of mesomorphs, instead leading to their criminality rather than the body type directly.
- Chromosomal abnormalities – The ‘extra Y syndrome’, which gives males another Y chromosome at prenatally, contributes to increased dominantly masculine traits, including aggression as these individuals possess more testosterone.
Though this is a logical theory, many studies are inconsistent with it. it has been found that XXY males are not actually as predicted (Graham et al 2007). These individuals have normal testosterone and aggression levels; they are taller but not necessarily more powerful. They are prone to developmental disorders and learning difficulties, which may perhaps make them more prone to criminal activity. Witkin et al (1976) found that 12/4500 men had the extras y syndrome but none of these 12 were offenders. Though XXY is rare in the normal population but over represented in the criminal population (Epps 1995), there is self evidently a range of environmental factors which also affect the likelihood of offending.
Perhaps then, as both nature and nurture are seen to affect the likelihood of offending, the diathesis stress models should be adopted. Factors considered in modern biological theories, such as Taumatic Bain Injury (TBI) do just this.