Of the 23 pairs of chromosomes that make up the genome of a healthy individual, only a couple are sufficient to determine a person's sex. In fact, women have two X sex chromosomes, while men have an X sex chromosome and a Y chromosome.
There are several genetic diseases due to sex chromosomes, one of which is Jacobs syndrome or more simply XYY syndrome . XYY syndrome affects the male sex and is characterized by the presence, in the cells of affected males, of two Y chromosomes.
Around the 1960s, in various parts of the world, scientific studies began to demonstrate a connection between criminal and genetic behavior. Therefore, for their investigations, the researchers began to examine the prisoners and the genetic profiles of the latter. From the analysis of male prisoners, it turned out that some of them possessed an XYY genetic make-up: this led scientists to believe that the presence of the double YY was a determining factor in increasing a man's aggression and violent delusions .
