Testosterone is significantly correlated with aggression and competitive behaviour and is directly facilitated by the latter. There are two theories on the role of testosterone in aggression and competition.  The first one is the challenge hypothesis which states that testosterone would increase during puberty thus facilitating reproductive and competitive behaviour which would include aggression.  Thus it is the challenge of competition among males of the species that facilitates aggression and violence.  Studies conducted have found direct correlation between testosterone and dominance especially among the most violent criminals in prison who had the highest testosterone levels.  The same research also found fathers (those outside competitive environments) had the lowest testosterone levels compared to other males. 
As for the flip side of testosterone cypionate, there is not much of a difference when it is compared to all other kinds of testosterone steroids . Some of these effects are simple and can be managed but others are long term effects that come with long term use in large doses. Most of these are permanent. Acne and hair loss can be managed by the cessation of the usage of testosterone cypionate but gynecomastia cannot. The presence of estrogen in the body after aromatization will lead to the development of breasts in men, which is not a pleasant sign. A lot of this female hormone is not good for women too, since it can lead to the development of male sexual characteristics which can lead to infertility due to the cessation of menstruation.
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