In arguing that IQ is a significant cause of crime, the researchers cite studies to indicate that criminal populations generally have an average IQ of about 92, 8 points below the mean. They also note that the relationship of IQ to criminality is especially pronounced in a small fraction of the population, primarily young men, who commit a disproportionate amount of crime and that high intelligence provides some protection against lapsing into criminality for persons who are otherwise at risk. Nonetheless, explanations of crime based on race, genetics, or biology have been shunned since the 1930's. From a sociology of knowledge perspective, the idea that traits, including IQ, are passed on through genes instead of through cultural transmission (learned behavior) is considered by many individuals to be empirically absurd and politically incorrect. Hence, a significant amount of controversy has been generated by researchers who contend that crime is based on low IQ. Critics point out that crime rates vary dramatically between and even within the same generation. They further indicate that, because IQ is not likely to increase or decrease in such a short span of time, IQ does not have a measurable bearing on crime. These critics insist that explanations of crime must be found elsewhere and emphasize traditional theories linking environmental factors such as culture, socioeconomic status, neighborhood, and peers with crime and delinquency. Many criminologists argue that intellectually disadvantaged persons are not more likely to commit crimes and indicate that efforts to link IQ, race, genetics, or biology to crime result in mean-spirited and repressive policy conclusions. 5 references