A theoretical sexless world
On the planet Winter in The Left Hand of Darkness, people are all sexless except during "kemmer," a monthly hormonal cycle. When it lines up with another person's kemmer, one spontaneously becomes male and the other female, never knowing who will be which until it happens. Sex and procreation can only happen during this brief phase.
Most importantly are its impacts on society:
Consider: Anyone can turn his hand to anything. This sounds very simple, but its psychological effects are incalculable. The fact that everyone between seventeen and thirty-five or so is liable to be (as Nim put it) "tied down to childbearing," implies that no one is quite so thoroughly "tied down" here as women, elsewhere, are likely to be—psychologically or physically. Burden and privilege are shared out pretty equally; everybody has the same risk to run or choice to make. Therefore nobody here is quite so free as a free male anywhere else.
Consider: There is no unconsenting sex, no rape. As with most mammals other than man, coitus can be performed only by mutual invitation and consent; otherwise it is not possible. Seduction certainly is possible, but it must have to be awfully well timed.
Consider: There is no division of humanity into strong and weak halves, protective/protected, dominant/submissive, owner/chattel, active/passive. In fact the whole tendency to dualism that pervades human thinking may be found to be lessened, or changed, on Winter.
Another guess concerning the hypothetical experiment's object: the elimination of war. Did the Ancient Hainish postulate that continuous sexual capacity and organized social aggression, neither of which are attributes of any mammal but man, are cause and effect? Or, like Tumass Song Angot, did they consider war to be a purely masculine displacement-activity, a vast Rape, and therefore in their experiment eliminate the masculinity that rapes and the femininity that is raped? God knows. The fact is that Gethenians, though highly competitive (as proved by the elaborate social channels provided for competition for prestige, etc.) seem not to be very aggressive; at least they apparently have never yet had what one could call a war. They kill one another readily by ones and twos; seldom by tens or twenties; never by hundreds or thousands. Why? It may turn out to have nothing to do with their androgyne psychology. There are not very many of them, after all. And there is the climate. The weather of Winter is so relentless, so near the limit of tolerability even to them with all their cold-adaptations, that perhaps they use up their fighting spirit fighting the cold. The marginal peoples, the races that just get by, are rarely the warriors. And in the end, the dominant factor in Gethenian life is not sex or any other human thing: it is their environment, their cold world. Here man has a crueler enemy even than himself.