The Cage of Zeus by Sayuri Ueda gives us a not-too-distant future of human exploration and habitation of our solar system, where an experimental project in the Jupiter System has engineered the Rounds: humans with ‘both’ sex organs whose gender is neither male nor female.
The reasoning for this is given early:
“To resolve the issues raised by gender differences... We’re incapable of eliminating the conflicts stemming from the differences in the sexes. And that’s only natural. Our physiology is different. So are our hormonal cycles. There’s no way to understand the other completely... But now as we’ve left the tiny confines of the solar system and are attempting to embark on a journey into the dark expanse, we can’t afford to quibble over such trifling matters. Which is why we should dispense with the problems that can be resolved by reinventing the body. A society where we are all equals, where only individual differences exist.”