A startling paper published in The Journal of Neuroscience points to evidence that there are molecular level differences between women’s and men’s brains.
From the abstract:
“Many brain disorders vary between the sexes, yet the degree to which this variation arises from differential experience versus intrinsic biological sex differences is unclear. In this study, we demonstrate intrinsic sex differences in molecular regulation of a key neuromodulatory system, the endocannabinoid system, in the hippocampus. Endocannabinoids are involved in diverse aspects of physiology and behavior that involve the hippocampus, including cognitive and motivational state, responses to stress, and neurological disorders such as epilepsy. Our finding that molecular regulation of the endocannabinoid system differs between the sexes suggests mechanisms through which experiences or therapeutics that engage endocannabinoids could affect males and females differently.”
As always, we should wait for additional confirmation before accepting these results.
peakmemory 
Let’s hope this paper doesn’t get retracted …