Gethenians are a variant of humans who are ambisexual (having both male and female sex characteristics) most of the time: for the majority of each month they are in somer, a neutral state with no fixed sex and no sexual drive. During Kemmer, which lasts a few days, their bodies temporarily become male or female. Which sex they take on isn’t fixed in advance—it depends on hormonal interaction with a partner. One partner becomes male, the other female, and they can reproduce during this time. What sex a Gethenian is can vary across kemmerings with the same partner, and at different times in their life. Outside of kemmer, sexual roles and drives simply don’t exist.