Benzophenone-3 ( Table 2 ). Male adolescents in the 3rd and 4th quartiles of BP-3 had significantly lower TT [–%; 95% confidence interval (CI): –%, –%; and –%; 95% CI: –%, –%, respectively, based on model 1] than males in the lowest quartile. Although the association was strongest for the 3rd quartile, the overall trend was significant ( p -trend = ). This pattern of associations persisted following adjustment for BPA, TCS, and ΣPAR (model 2). In female adolescents, TT was significantly higher for girls in the second versus first quartile of BP-3 exposure, but positive associations were closer to the null and nonsignificant for the 3rd and 4th quartiles of exposure ( p -trend ). Associations were similar after adjustment for BPA, TCS, and ΣPAR, but no longer significant for quartile 2. There were no significant associations between TT and BP-3 in male or female children, and no evidence of consistent trends with increasing quartiles of exposure.
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.     
A survey of 28,000 users found that many Italian males started an "excessive consumption" of porn sites as early as 14 years old. After daily use in their early to mid-20s, they become inured to "even the most violent" images. The effects of developing their sexuality largely divorced from real-life relationships are gradual and devastating. "It starts with lower reactions to porn sites, then there is a general drop in libido and in the end it becomes impossible to get an erection," Carlo Foresta, head of the Italian Society of Andrology and Sexual Medicine (SIAMS), told reporters. However, the condition is not irreversible and a proper recovery is possible within just a few short months.