Cell X is female. XD
The lack of Saiyan DNA/Saiyan DNA doesn't manifest, making her closer to the insect-like characteristics that govern her basic biology (female predatory insects are larger than males).
However, we know that perfect Cell typically has balanced Saiyan DNA. Therefore, his height is significantly reduced because, among Saiyans, females are smaller than males, similar to humans.
Of course, even though Cell seems to have been created genderless, his true gender is known in the official Japanese team. But when it was released internationally, the team chose to use "he" instead of "she," because it better suited his personality, and even Japanese fans liked it because he looked like a truly perfect young man. And, thinking of him as male or intersex fulfills the fantasies of many female fans more than his actual gender.











