Well according to Onica, Soothsaying and Far-Dreaming are not the same. @CrazyDrenchen08 and I have basically agreed that (at least in our alternate canon) that Soothsaying is when someone predicts future events, while far-dreaming deals with the present.
Yeah but besides that, he doesn’t seem to have that great a grasp on the concept. Besides, in 1982, they didn’t have the nuanced ideas of gender that many of us do now. He knows he had a mother and a father, but even then Gelfling gender roles don’t seem to be quite the same as the ones here on Earth
Jen was raised around genderless beings, so I wouldn’t be surprised if he wasn’t familiar with the concept of the gender binary. He doesn’t ever even call himself a boy, it’s only Kira that does. Even after the “you’re a boy” statement, Jen appears to be confused.