Of all the factors that can influence criminal behavior, biological influences can definitely play one of the more important roles. Several areas of research support ideas of a genetic influence as well as neurological defects and chemical imbalances that play into motivations of criminal activity. More recent than in the past, biological studies have been carried out, and they have been finding that biology can often be a significant effect on crime. In 1997, Anne Moir and David Jessel printed a book called A Mind to Crime, which looked at various biological tested effects on crime. .
In the book A Mind to Crime, one of the primary ideas discussed is the genetic theory on crime. Mainly, a description is given how environmental factors interact with genes, which can cause one to be more active in crime; therefore, one gene does not cause crime, but if certain genes interact with environmental factors, then crime is more likely. An example of this possibility is the presence of a gene that can make one more aggressive. This aggressive gene may interact with outside influences where the criminal may be placed in violent or unpleasant situations, which will cause him to act in a criminal manner. Moir and Jessel say, "Genetic theory has advanced in sophistication, and we know that environment factors can interact with the genes, as it were switching messages on or off." They also continue to describe that without this genetic predisposition, one is less likely to partake in criminal activities. This genetic theory also discusses that there are certain genes that predispose some towards non-violent property crime, and genes that predispose others to violent behaviors. This provides further evidence that not only can a biological factor influence crime in general, but all types of crime in that it shows how biology effects genetics which in turn can cause a criminal predisposition, not only in general crime but in certain types of crime.