Biological theories of crime, which date back to the 19th century, argue that whether or not people commit crimes depends on their biological nature. In other words, some individuals would be predisposed to crime because of genetic, hormonal or neurological factors which are inherited (present at birth) or acquired (through accident or illness). Most criminal biologists have abandoned the idea that delinquency can be explained only by biological deviations in the "offender", preferring approaches that combine biology and sociology.
In the 1800s, an Italian criminologist, Cesare Lombroso, published L’Uomo delinquente (“Criminal Man”). In it, he described criminals as atavistic beings, or people who were less developed as humans. While examining the skulls of criminals, he noticed a series of features that were common. For example, Lombroso found similarities in the sizes and shapes of jaws, ears, and chins. Lombroso referred to criminally-labeled people as “evolutionary throwbacks” whose behaviors were more "apelike" than human and this imputed inferiority of the criminal permits treating them without moral or ethical considerations.302 Lombroso’s criminal anthropology presumed you could identify a member of the criminal race by certain visual signs or stigmas (like the visual physical characteristics listed above).
However, the studies carried out by Lombroso lacked the scientific rigor expected today, and, more importantly, some of the features described by Lombroso are linked to skin color and other traits often associated with the concept of race. Lombroso’s theories provided a significant ideological basis for systemic and institutionalized and racism. In sum, Lombroso’s biological theory of criminality was full of biased ideology and has since been largely dismissed by most of the scientific community and is often referred to as "scientific racism".303 In fact, “throughout his writings are clear and appalling passages with overt racist and sexist overtones that are consistent with a eugenics perspective of the human population.”304 However, even while much of the scientific world has discounted Lombroso’s findings, his findings have had lasting impacts on social views and consequences of crime and "the criminal."
XYY "Supermale" Syndrome
Another biological theory attempting to explain sex and gender differentials in criminal behavior was known as the XYY Syndrome theory. XYY syndrome is a genetic condition in which a human male has an extra male (Y) chromosome, giving a total of 47 chromosomes instead of the more usual 46. This produces a 47,XYY karyotype, which occurs every 1 in 1,000 male births. The presence of the extra Y chromosome in XYY males does not in and of itself produce aggressive behavior in those affected; dealing with aspects of the condition during adolescence is a more likely explanation for any delinquency or criminal behavior exercised by XYY males.
As early as 1974, prominent geneticists Jon Beckwith and Jonathan King called the notion of a dangerous XYY “Supermale” Syndrome a dangerous myth. This idea was primarily based on assumptions about the tendency of males to be more aggressive than females and early studies of XYY males in prisons.305 However, while males with an extra Y chromosome are still widely believed to show more signs of aggression, not all aggression is dangerous or violent. Meaning, aggression can be demonstrated on the soccer field or in the classroom or boardroom. Thus the theory of the extra Y chromosome creating a predisposition for violent or criminal behavior has fallen short.
302 Lombroso, Cesare. 2006a. “Criminal man: Edition 1.” In Criminal man. Edited and translated by Mary Gibson and Nicole Hahn Rafter, 39–96. Durham, NC: Duke Univ. Press. 303 Regoli, R. M., Hewitt, J. D., & Delisi, M. (2010). Delinquency in society (8th ed.), Boston: Jones and Bartlett. 304 DeLisi, Matt (2013). Cesare Lombroso. obo in Criminology. doi: 10.1093/obo/9780195396607-0165 305 Gotz, M. J., et al. "Criminality and Antisocial Behavior in Unselected Men with Sex Chromosome Abnormalities." Psychological Medicine 29 (July 1999): 953-62.