Fountain of Knowledge

Most of the humans I know would be to lazy to figure it out and just call them all "it."

When you think about it, there's no real reason for pronouns to have genders; it just happens to be the way things worked out in English. We could just as well have different pronouns according to age, for example.

I've got one story with three-gendered aliens. Since their sexual identities are similar to bees, I think I called them males, mothers, and steriles (short for sterile females, the workers).