The second theory is similar and is known as "evolutionary neuroandrogenic (ENA) theory of male aggression".   Testosterone and other androgens have evolved to masculinize a brain in order to be competitive even to the point of risking harm to the person and others. By doing so, individuals with masculinized brains as a result of pre-natal and adult life testosterone and androgens enhance their resource acquiring abilities in order to survive, attract and copulate with mates as much as possible.  The masculinization of the brain is not just mediated by testosterone levels at the adult stage, but also testosterone exposure in the womb as a fetus. Higher pre-natal testosterone indicated by a low digit ratio as well as adult testosterone levels increased risk of fouls or aggression among male players in a soccer game.  Studies have also found higher pre-natal testosterone or lower digit ratio to be correlated with higher aggression in males.     
As for individual use of a personal nature, outside therapeutic treatment, this is where we will find the vast majority of anabolic steroids. It is here we will also find the biggest problems, not in terms of ill-effects of a physical or mental nature but of those surrounding legality. In places like the . anabolic steroids are controlled substances, and here we will find the strictest of laws. This has created a new class of criminal; most commonly an adult man with a family who is simply living an every day life like everyone else. These are issues that need to be discussed and you will find very few are willing to touch them unlike .