MZ twins are genetically identical, while fraternal twins only share half their genes.
Rowe, David and Bill Gully. Jealousy, for example, is a human emotion that may have evolved in order to keep families together and increase the probability of reproduction see Seigel and McCormick, For instance, examining the limbic system in psychopaths and comparing to non-psychopathic controls, functional magnetic-resonance imaging scans fMRIs detected both structural and functional differences between the experimental and control groups; specifically, activity within the amygdala and hippocampus was reduced in the psychopath group, as was the volume of the amygdala reduced by seventeen to nineteen percent Beaver, Horney, Julie.
A number of important studies have found a significant relationship between hypoglycemia and violence — including assault, homicide and rape. In its most serious form, MDB is associated with severe anti-social behaviour, including hyperactivity, poor attention span, temper tantrums and aggressiveness.
From such an example, biosocial criminologists acknowledge that the environment alone does not create the expression of aggression within individuals, but instead the development of aggressive behavior is partially driven by biological factors in conjunction with environmental influences.
Researchers have tried to overcome this obstacle by comparing identical MZ twins with fraternal DZ twins of the same gender.
Barnes, J. Alcohol and violence and the possible role of Serotonin. Arousal theory and the religiosity-criminality relationship.