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. 
I can confirm this to be true. I get my testosterone checked regularly along with my TSH numbers. For some reason my TSH is never a consistent number and my testosterone levels have been in the crapper for a long time. Even with testosterone supplements my levels didn’t improve much, if at all. Last July my doctor said my PSA numbers were a bit high so he told me to stop taking the Andriol, the testosterone supplement. Fast forward to December when I started taking 2000 IU of vitamin D per day. I had my blood tested again a few weeks ago at the end of February and my doctor said my testosterone levels were higher than they’ve been over the last few years while taking supplements.
All bets are off the table when high-dose testosterone and its many metabolites are used illegally, such as with anabolic steroid abuse. Strokes, embolisms, and cardiovascular disease are all more likely, as is sudden death, and liver and kidney disease. 44 In women, acne, irreversible deepening of the voice, baldness, increased facial hair, enlarged sex organs, breast reduction, depression, and infertility have all been reported. In adult men that abuse anabolic steroids, acne, baldness, permanent infertility, gynecomastia, loss of libido, erectile dysfunction, testicle shrinkage, and profuse sweating are all reported side effects. Increased testicular cancer hasn't been reported, though. 45,46