And why do women for the most part not start wars?
Several explanations to both of these questions come to mind that are based on hormones, brain anatomy, and mirror neurons.
Oxytocin is the hormone that is both released by emotionally bonding to another person and then increasing that bonding. It goes way up in women during child birth and during nursing afterwards. Interestingly oxytocin levels are about the same in women and men, but estrogen in women causes the oxytocin to exert more of an effect in women. Emotionally bonding to others is antithetical to staying focused on a goal to the exclusion of all human emotional connection.
Years ago I heard of an experiment where boys and girls were playing volleyball (before both started playing club volleyball). In the games that boys played, they stuck to the rules; whereas in the game that girls played, they would bend the rules to add another player on the court rather than leave her excluded. Men bond with other men in service of a goal, but they don't often bond just for the sake of closeness itself. To excel in technology and for that matter, be a "rocket scientist," staying focused on the goal, the strategy and tactics to get there are critical.
A second explanation for why there are so few women in technology is because in their brain anatomy, women have a thicker corpus callosum than men. The corpus callosum is the fiber network that connects the left and right hemispheres. The thicker it is, the more that the emotional right brain and logical left brain communicate and mitigate purely emotional or purely logically directed behavior that one engages in. This may explain why men can either become coldly logical or become violently emotional around sports and around making war, because when they are coming from either their logical or emotional brain they are coming purely from either. This might also explain why women don't wage war, because when logic directs one towards a "zero sum" game, war can sometimes seem like the only alternative when the emotional bull inside men see "red."
A final explanation may be due to the area of the brain referred to as the mirror neuron region. Mirror neurons are called that because they are activated when you watch someone do something, which is why you yawn after seeing someone else yawn. They are also hypothesized to play a key role in imitation (having been first discovered in macaque monkeys and called, "monkey see, monkey do" neurons), learning and empathy. Evidence has also demonstrated that there may be a relationship between deficient or defective mirror neuron functioning in people with Asperger's Syndrome and autism (since they seem to both have trouble tuning in to visual cues and empathy). This may also explain why so many people, loosely and cavalierly refer to techies as having Aspergers' (as Bill Gates is thought to have). It may be possible that the mirror neuron function in the empathy department is more highly functional in women than men (see: Mirror Neuron Receptor Deficit).
The takeaway from this not to get into an "either or" "right or wrong" debate about men versus women in technology, but to utilize the differences in a complimentary way that will together help them both make the world better.