In this essay, I posit that the ’aylonit essentially receives her sex/gender assignment from her parallel, the natural eunuch. I reach this conclusion by demonstrating that the aggregate simanim (signs) of the ’aylonit are chosen specifically for their sex/gender-crossing attributes, fitting neither any known modern condition nor any ancient condition. Given that in the legal material the rabbis do not, in fact, understand the ’aylonit as a sex/gender crosser, the list of attributes seems to emerge from nowhere. The answer to the riddle of its origin is to be found in the text describing the seris ḥammah (the congenital eunuch, whose description parallels that of the ’aylonit in many ways). That is, the simanim of the seris ḥammah also present him as a sex/gender crossover despite the lack of supporting halakhic literature. But whereas the ’aylonit has no ancient corollary in the Greek and Roman literature, the attributes of the seris ḥammah directly match those of the Roman eunuch, who does appear in many of the contemporaneous Christian and Roman materials as a sex/gender crosser. It would seem, then, that the seris ḥammah shares his sex/gender with the Roman eunuch, and the ’aylonit receives her sex/gender from her mirror image, the seris ḥammah.