According to you, "changes in the wiring of the brain" are "based on physical differences". Is difference of opinion anything other than a difference in the wiring of the brain? If you don't believe in the supernatural, then the answer is no, and you've contradicted yourself.

This happens surprisingly often when you defend stuff that you don't really believe.

I confess that my point was poorly worded.

"Wiring of the brain" was a poor cliché to use to refer to the innate physiology of the brain, if accuracy is demanded. The physiology of the brain, of course, does differ in a number of general senses between males and females.

Opinions, however, are typically based upon memories - and judgments built upon those memories - although emotion and some hormonal factors (such as serotonin and dopamine levels) have a significant effect too.

Short term memory and the executive acts of judgment are defined by variations in potentiation between neurons in the prefrontal cortex. Whether or not you consider "electrical" patterns in the brain to be as "physical" as actual brain layout is, of course, likely to remain a contentious point.

Now.. if you take it out to long term memory, you might, at least, have forced a stalemate. Long term potentiation between certain neurons (as in the formation of long term memory) does, indeed, result in a "physical" change through the formation of synapses. I don't personally consider these changes as "physical" in the sense of my original argument (which was not written with the consideration I'd need to back up the terminology used) but I accept that there is a potential stalemate here, since almost everything can be reduced to physicality depending on how detailed a view you wish to take.

My argument is really that attributes free will cannot change (such as biological gender) are physical in nature, whereas those attributes free will can adjust are not. In this sense, I maintain gender is entirely based upon physical attributes, whereas other human attributes are not necessarily.

I've calmed down a bit now, so I don't want to belabor it any more. It seemed to me that you originally used the phrase "physical attributes" to refer to what most people would mean by it--height, weight, body fat ratio, skin color, bone density, sex organs, and so on. This is the official PC line on what the main (only?) difference between genders is, and it's an evil lie. If you really meant it in this (rather contrived, IMO) way that you've outlined just now, then I suppose we don't really disagree.