Although a lot of neuroscience research has identified sexual dimorphisms in neural structures and behaviors, on average differences in ability are very small (as Damore clearly emphasized in his memo). A potential reason for the 80:20 sex distribution in engineers is that Google is effective at identifying and hiring outstanding engineers, i.e. the people at the far end of the bell-curve where there are many women, it's just that men are over-represented in that region of the histogram.

I think you raise an important point with respect to the neuropathology of this particular case (Eliot Rodger). His monolog reflects a narcissistic ego- entitlement with no personal responsibility. He may have had organic issues like autism or even schizophrenia but his long history of therapy did not overcome the narcissism that seems to have driven him to this maniacal act. What do therapists do for people like this? Are they doing any good at all?