in school. Unfortunately, H.H. Goddard, like many Americans at the time, believed intelligence was innate 
and static. That is, intelligence was fixed and could not change. Goddard gave IQ tests to sort people and 
those who scored too low were institutionalized, deported, or sterilized. He was an early advocate to sterilize 
those who were mentally deficient, especially “morons,” who were just smart enough to blend in with the 
normal population. In 1927, the United States Supreme Court in Buck v. Bell allowed the use of sterilization. 
Even after Lombroso, Goring, and Goddard, contemporary research reveals intelligence is at least as 
critical as race and social class for predicting delinquency (Hirschi & Hindelang, 1977).
2 However, how 
we measure intelligence and how we define intelligence are based on our preconceived assumptions of 
intelligence. For example, is intelligence inherited? Is it related to the dominant culture? Or is it based more 
on the person’s environment? Each has a least some element of truth. 
Modern biological theorists have revealed that biology plays a role in our behavior, but we cannot say 
how much or even how so. Twin studies and adoption studies examined the nature versus nurture debate. 
Both play a role in our behavior. It is more nature and nurture. Perhaps the question ought to be “how do 
our biological differences interact with our sociological differences?” There is not a crime gene per se, but 
some genetic variations are correlated with anti-social behaviors. However, those with genetic variations are 
not necessarily criminal because of genetics. Though it puts the individual at risk for such behaviors, a caring 
and supportive environment often mitigates the impact of the genetic code. 
Proximate causes, such as neurotransmitters, hormones, the central nervous system, and the autonomic 
nervous system, have links to aggressive behavior too. However, many of these explanations have several 
possible causal paths. For example, we know people with higher testosterone levels engage in more 
aggressive behavior, but when people engage in aggressive behavior, their testosterone levels increase. We 
do not know which causes which. 
What about criminal personalities? What about sociopaths and psychopaths? The Gluecks (1950) 
determined there was no real criminal personality; instead, there are some interrelated personality 
characteristics that were clustered together.
3 Even after giving personality tests to criminals and non-
criminals, there does not seem to be any logical relevance to understanding the causes of crime. However, 
there have been correlations between certain personality traits and criminal behavior. For example, 
impulsivity, lack of self-control, inability to learn from punishment, and low empathy have all been linked 
to criminal behaviors. 
Consequently, none of these personality characteristics are criminal in and of themselves. The real danger 
is when a person has many of these personality characteristics. Capsi et al. (1994) found that constraint 
and negative emotionality, two super traits that contain a number of different characteristics, were “robust 
correlates of delinquency” (p. 185).
4 
In summary, researchers have been able to say that our biology and personality play a role in criminal 
behaviors, but we cannot say how much or to what degree. The characteristics of our social environment 
interact with our biology and personality. Human behavior is quite complex and it is difficult to determine 
the true causality of human actions. 
 
2. Hirschi, T., & Hindelang, M.J. (1977). Intellegence and delinquency: A revisionist review. American Sociological Review, 42, 572-587. 
3. Glueck, S., & Glueck, E. (1950). Unraveling juvenile delinquency. Cambridge, MA: Harvard University Press. 
4. Capsi, A., Moffitt, T.E., Silva, P.A., Stouthamer-Loeber, M., Krueger, R.F., & Schmutte, P.S. (1994). Personality and crime: Are some 
people crime prone? Replications of the personality-crime relationship acrass countries, genders, races, and methods. Criminology, 32(2). 
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