Why are 90%+ violent acts throughout history committed by men?

[Loki Liesmith]

3. Lots of interacting factors

In part men are physically optimized for successful acts of violence (via increased size and strength, as statistical quantities). Men may also be psychologically optimized for violence, with lower capacities for empathy and lower thresholds towards activation of violence. Indeed it would be plausible for men to have lower inhibitions against conspecific violence given that they possesss the tools for such violence.

The extent to which the latter is innate is, of course, not clear, but one suspects that some of it is, at least.