Of course, for Equality of Chance to be properly implemented you need to do away with as many barriers to it as possible but you should be willing to accept that no matter what you do, there won't be a perfect 50/50.
From all evidence we have, there is strong evidence that male and female humans grow up differently independent of their social surroundings, for example, we found that the brains of newborns can be easily distinguished into female and male as little as 1 month after birth, before any social factors have had much chance to get deep into development.
From that I find it easier to believe that there will be some statistical biases in one direction or another (like how will have, on average, a bit more height) outside of the purely physical domain.
I would rather see some evidence that despite all the physical, hormonal and developmental differences in male and female humans, there is absolutely no statistically significant difference in the brain and/or mind.