What I think doesn't really matter, what does good research show?

Transgenders? Violence against transgender people in the US, both passive-aggressive and direct, is statistically higher than other genders. The murder rate for transgender people is higher than other genders. I have a lovely transgender niece I worry about.

Aggression could be both nature and nurture. With psychopaths, as I remember, it is nature. Nurture probably just intensifies it, i.e. whether one has their needs met as an infant/child/young adult, or not.

Testosterone levels are higher in individuals with aggressive behavior. Prisoners who commit violent crimes are one example. Testosterone increases during the aggressive parts of sports.

I have seen both women and men be physically violent, but more often men. More serial killers are men.

There appears to be evidence that females use indirect violence more effectively than males.