LRD - "third-wave feminists - people who'd say that a tomboyish girl was 'genderqueer'."
I'm intrigued by this (and have to admit I have read no gender queer theory) - why would one think this? (I was a total tomboy, probably still am, but I've never had any doubts that I was female, and was aware at a very early age that I'm predominantly heterosexual). I suppose my puzzle is that gender/sex discussions, and discussions about sexuality seem to me to occupy slightly different (albeit overlapping) conceptual spaces.
Re. the OP, I'm of the school of thought which says that for almost any putative difference (reading ages, athletic abilities in childhood, maths ability, etc) that you examine, even if you can measure a small difference in the means of the two populations, the standard deviations for each population are huge compared to this small difference. This is the so-called d-value: delta mu / (sigma1 * sigma 2) and is small for most gender differences. For e.g. suppose you identify a mean reading ability for 6 year old girls as being slightly in advance of the mean reading ability of 6 year old boys - this isn't a useful fact in isolation, unless you include the fact that, say, 45% of boys out-perform the mean level in girls (and in addition, if you're doing your stats properly, you should be including information about the confidence level - so, difference in mean performance is significant at, say, the 95% level, i.e. there's a 1 in 20 chance that your difference in performance could be down to sampling error). So applying statistical measures like this to individuals drawn from the population is a totally pointless exercise.
Also, given the plasticity of brain development and the fact that gender stereotyping starts at birth, even where you identify a difference in mean performance (which, as noted, usually has a small d value) it would be almost impossible to attribute this unambiguously to nature or nurture.
Fingers crossed DS is beginning to come out of the peer pressure phase. Having gone from a massive enthusiasm for pink and sparkles aged 3 to "blue is for boys" aged 4, he's now finally saying things like "it's not fair to say girls can't do that/won't be interested in that toy", and has decided he likes green best.