In a society where humans have advanced technology so far that we can reach the moons of Jupiter, gender and sexuality is an issue. People can change physical sex however they wish, or even have the organs of both, but humanity has come much further in bioengineering than that.
On Jupiter-I, a space station in orbit around Jupiter, we find the Rounds. They are so-called true intersex, and they naturally have both male and female traits. They are humans whose DNA is different from the people who created them. However, not all are happy about the engineered humans, and now Jupiter-I is targeted by the terrorist group The Vessel of Life.