I still can't understand this line of thought as anything but insane. In a world with only one gender, humans would cease to be capable of true thought? If a person does not experience thought tightly linked to gender and sexual difference, they do not think? Philosophy of thought at this level is basically thought experiments, and I personally can't construct any thought experiment where that makes any sense whatsoever. Surely there is a strong link between the way humans tend to think and their physical embodiment, which has some variation by sex, but that is an entirely different statement.