Viewpoint: Yes, the best studies of XYY males indicate that they are more prone to aggressive behavior than XY males. Viewpoint: No, the presence of the extra Y chromosome in XYY males does not in and of itself produce aggressive behavior in those...

XYY syndrome is a chromosome disorder that affects males. Males with this disorder have an extra Y chromosome. The XYY syndrome was previously considered the "supermale" syndrome where men with this condition were thought to be overly aggressive and...

The XYY karyotype was first described in a 1965 study of 197 males in a Scottish maximum-security prison. The study's findings indicated that 4.5% of the violent offenders studied had the XYY karyotype. Subsequent surveys by other researchers indicated...

A very rare chromosome abnormality (see CHROMOSOME ABNORMALITIES) in which a male has an extra Y chromosome. It has been rather sensationally associated with criminality, but there is now considerable doubt as to the validity of this controversial...

XYY syndrome is an aneuploidy (specifically a trisomy) of the sex chromosomes in which a human male receives an extra Y chromosome, producing a 47,XYY karyotype. Some medical geneticists question whether the term "syndrome" is appropriate for this...