Thanks for the link for the review paper, I'll have a better look when I get chance. Although, the abstract does echo what I wrote in my first post:

"Although there are sex/gender differences in brain and behavior, humans and human brains are comprised of unique “mosaics” of features, some more common in females compared with males, some more common in males compared with females, and some common in both females and males. Our results demonstrate that regardless of the cause of observed sex/gender differences in brain and behavior (nature or nurture), human brains cannot be categorized into two distinct classes: male brain/female brain."

There's still a lot we don't understand when it comes to neuroscience, although from my understanding there are certain areas that are more in flux than others. The point you make about plasticity and how the environment might cause sex brain differences is an interesting one and something I haven't read a lot into. It's possible that pressure to conform to gender stereotypes for example, might cause changes in the brain and account for some of these differences. Having said that, the evidence for innate biological differences is very strong so the interesting question from my perspective would be to what extent does the environment act on these innate differences.