Kevin Lamb’s excellent article (“Crime Genes and Other Delusions,” December 1996) illuminated recent behavioral genetic research on temperament and its relation to crime and showed that scientific interest of this kind is growing rapidly, despite continued opposition from the political correctness crowd. Coincidentally, two new articles of mine bear directly on this issue.

In the July 1996 issue of the medical journal Psychiatric Genetics, I examined data from several hundred twin pairs and found that general misbehavior for men is about 75 percent heritable and that violence is about 50 percent heritable. The measures of violence included carrying and using a weapon, fighting in public, struggling with a policeman, and vandalism. This may have been the first study to show that violence per se is heritable, for even some behavioral geneticists relate violence to alcohol and/or drug abuse, perhaps implying that it is less heritable.

In an article in the October 1996 issue of Aggressive Behavior, I demonstrated that testosterone is related to aggressive behavior in both men and women. We obtained testosterone samples from the saliva of 300 college men and women and asked them to complete questionnaires regarding their aggression and nurturance in different situations. Men had five times more testosterone than did women and reported themselves as more aggressive and less nurturant than did women. Both men and women with high testosterone felt more anger and aggression than their counterparts. Similarly, men and women with low testosterone felt more nurturance than their counterparts.

These new findings on the biology of crime have implications for racial variation in criminal behavior, given that blacks (on average) have more testosterone than whites, who have more than Asians. Although it is well documented that blacks m the United States commit more crimes of violence than do whites or Asians, it is seldom realized just how strong the race-crime relation is. Glayde Whitney, a president of the Behavior Genetics Association, published a paper in the 1995 issue of Mankind Quarterly showing a very high correlation (r = 0.77) between the percentage of blacks in a state and the state’s homicide rate. It is seldom officially noted that Orientals are underrepresented in American crime statistics relative to whites and have been ever since record keeping began.

Even less often noted is that this same three-way racial gradient in crime found in the United States is also found around the world. As I show in my book Race, Evolution, and Behavior (1995), African and Caribbean countries have twice the rate of violent crime (murder, rape, and serious assault) as do European countries, which in turn have twice the rate of violent crime as do Pacific Rim countries.

        —Philippe Rushton
Professor of Psychology
University of Western Ontario
London, Ontario