Aggression may also have a chemical, hormonal, or genetic basis too.
Steroid users sometimes have intense anger while taking the drug and for a
long time afterwards, called steroid rage. Of course, emotions and
behaviors are to some extent learned but genes play a role in this complex
matrix of causes. A large survey of adopted children has found that living with
an adoptive parent who committed crimes is less risky than merely having the
genes from a person who committed crimes (Mednick, Gabrielli & Hutchings,
1984). The power of human genes is discussed in chapter 4, but, obviously,
within animals certain breeds of dogs, like Pit Bulls, are more vicious than
others. More aggressive breeds can be developed, e.g. rats or fighting bulls.
Maybe we could and should develop kinder, gentler, smarter humans.
One may frequently hear that people with serious mental illness are not more
dangerous than the general population. That is good to hear because there is
such a stigma against mental illness. However, according to Janssen
the seriously disturbed, e.g. schizophrenia, bipolar, character disorders, and
substance abuse, report more violence during treatment and during follow-
up. As you might expect, patients who are hostile-suspicious, agitated, and
delusional are the most likely to be violent. Often the target is a family
member. Over half of Mental Health professionals have been assaulted by a
patient at least once (that wasnt true in my case).
As more studies of genes are being done, a complex interaction is being found
of specific genes with specific neurotransmitters, such as serotonin, or with
enzymes, such as monoamine oxidase A, which regulate mood and
aggression. Moreover, researchers believe they have found that traumatic life
experiences, such as being abused, have an impact on specific genes which,
in turn, increase the likelihood of anti-social behavior (Terri Moffitt, Kings
College London; Evan Deneris, Case Western Reserve University, School of
Medicine). Such findings are not useable now but they suggest future
Other physiological factors may be involved. Possible examples: high
testosterone (male sex hormone) is associated with more unfaithfulness,
more sex, more divorce, more competitiveness, and anti-social behavior.
Remember too that in the Introduction to this chapter it was mentioned that
the amount of testosterone available to the fetus influenced the length of
fingers which is related to physical aggressiveness. It is also known that a
viral infection, called rabies, causes violent behavior (pain causes
aggression). About 90% of women report being irritable before menstruation.
Furthermore, 50% of all crimes by women in prison occur during their
menstrual period or premenstrual period. By chance only 29% of crimes
would have occurred during those eight days. Hypoglycemia (low blood
sugar) increases during the premenstrual period and it too causes irritability.
Reportedly some women have a stronger sexual attraction to masculine men
when they are ovulating. About 3 times in a 1000 a male inherits an extra X
or Y chromosome, so they are XYY or XXY, instead of XY. At one time it was
thought that XYY and XXY males committed more violent crimes. Now it
appears that this isn't true but these males are arrested earlier and more
often. So we can't forget our inheritance. There is so much we do not know