Testosterone, Violence, Gender, and Race There are some who question whether the difference in crime rates between men and women is due to culture or genetics. The fact is that it's mainly genetics. Differences in testosterone/estrogen levels are among the most important differences between men and women, as these differences control a host of downstream processes. See here for a layman's discussion of the effects of testosterone. In particular, from salivary testosterone measurements alone you can definitively identify someone as male or female because there is essentially no overlap in the male/female testosterone distribution:

"Men and women differ biologically mainly because men produce 10 to 20 times as much testosterone as most women do, and this chemical, no one seriously disputes, profoundly affects physique, behavior, mood and self-understanding"

Furthermore, the effects of high testosterone levels have been well documented. You might have heard of it as roid rage, but across species, testosterone leads to increased violence in males and females. There is no dispute in the technical literature over whether testosterone is responsible for the differences in violence between males and females. An interesting fact that you may be unaware of is that studies from many different fields - from sports medicine to prostate cancer have shown that Asians < whites < blacks in testosterone levels:

Race and hormone levels: There seems to be a direct relationship between high levels of testosterone and high incidence of prostate cancer. Further, research has revealed a direct relationship between hormone levels and race. From a race standpoint, Asians are in the group of lowest testosterone and, therefore, at least risk of prostate cancer. Caucasians fall in the middle risk group. Blacks, who have the highest testosterone levels , have about twice the incidence of prostate cancer as other groups.

When combined with Interpol data, the implications for criminality distributions are clear.