Wow, someone actually found that on accident... those are actually two entwined snakes from Greek myth:
"One Greek myth of origin of the caduceus is part of the story of Tiresias,[18] who found two snakes copulating and killed the female with his staff. Tiresias was immediately turned into a woman, and so remained until he was able to repeat the act with the male snake seven years later."
Instead of trying to keep track of seven years of game time, I made the change permanent - though characters still seem to address the character as their original sex.
Congratulations, it's a girl!