Suzanne:

Of course we don't have to choose between nature and nuture. Clearly, BOTH genetics and environment play important roles in determining personality and gender differences. I think at least some of the differences in "perception and expression" are hard-wired. Men, for example, are probably more easily and quickly aroused than women, especially by visual stimuli. They can't help it; their bodies are just wired that way.

Your theory of solid versus liquid reactions to the mother is interesting; there may well be something to it. But in trying to explain why boys are different than girls you argue that the sense of a separate identity is "more painful for boys because they are more different from the mother than girls" and this is what leads to the crucial differences. But what makes boys "more different from the mother" in the first place? Isn't genetics the root cause? Even if this theory is correct, you seem to be saying that environmental influences AMPLIFY pre-existing genetic differences. I would certainly have no quarrel with that.

I completely agree that you can't count a person's self-assessment in deciding these matters. Such insights are at best circumstantial evidence.

Finally, I am not familiar with research at Stanford or elsewhere "which appears to be pointing toward a conclusion that sexual differences, in the brain, anyway, are not hard wired." I'm not sure what you mean, since the brain IS our hard wiring, but there are still a lot of researchers on both sides of this fence. I would like to hear more about this research if you can find the reference!