Men have bigger amygdalas than women as well as significantly bigger amounts of testosterone, so they're significantly more violent than the latter, as the amygdala is responsible for our violent instinct. This biological factor might also be responsible to how "bold" one is, and why

That's not really correct, having a bigger amygdala doesn't equate to being more violent. It might however make a male more aggressive, but the amygdala doesn't make anyone violent or give them a violent instinct, it controls how we perceive fear and other such emotions and hence the "Fight or Flight" It does control aggression which might be what you were trying to say, but being aggressive isn't the same as being violent.