Linking The Violent Extremists

Being America, when Nasim Najafi Aghdam opened fire at the YouTube headquarters last month the conclusion was this was yet another gun owning nutter in a land of lax gun laws which it was but the surprise was that it was a woman performing the gun violence.  
It is undeniable that virtually all of the violent extremists including mass shooters, right-wing extremists, anti-immigrant zealots, anti-Muslim skinheads, neo-Nazis, white supremacists and Jihad supporting Muslims are linked by one thing, their gender.
Most people who drift to the edges of the political spectrum and toward violent extremism and then commit acts of terrorist violence are young men and the fact that they are male hardly causes a ripple.
Of course there are violent extremist females also but so rare are they that when they do turn violent, their gender is noticed which proves the point that the extremist violence is the domain of the male.
In the case of the American shooters, leaving aside the easy access to guns and the pathetically weak gun laws which allow the mass shootings to happen, the usual back story is one of isolation or bullying but girls get isolated and bullied at school but are far less likely to pick up an assault weapons and 'pull a Columbine' at their high school.
Muslims may be angry at what the West have been doing to their region and that effects men and women equally but the Jihadists turning up on the streets or on TV beheading foreigners are hardly ever female.
If the world is such a hostile place then the question must be why are particular males more prone to violence and not all the others who have been through the same experiences and what makes these males so prone to lapse into such horrific violence?
They may be mass shooters, Jihadists, neo-Nazis or white supremacists and it may seem irrelevant in the wake of the loss of life, but it is highly likely that they will be linked by gender as it is extraordinarily rare that they will be female so maybe that's where we should be looking for the answer to why.