Of course, we said there were two testosterone related Winstrol side-effects , the first being testosterone suppression and the second being testicular atrophy. As testosterone is manufactured in the testicles, when production is suppressed the testicles simply atrophy. They do not shrink and disappear; in-fact, in some cases the difference may not be all that noticeable. When we’re speaking of testicular atrophy we’re simply referring to the testicles losing some of their fullness. Once the use of all anabolic steroids has been discontinued and all the hormones are out of your system natural testosterone production will begin again, and your testicles will return to their normal size.
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.