There was a time when there were only two sexes and three genders. Those were the days when sex pertained to plants and animals and gender pertained to language, so that the sexes were male and female, while the genders were masculine, feminine, and neuter. Because men were regarded as the primary sex, we tended to use masculine pronouns even when the sex of the individual was unknown or indeterminate, as in, “Someone left his pen on the table.”
When men got together with other men to do manly things like fight a war, run a business, or sail a ship, the result was that lots of things were referred to with masculine and neuter pronouns, with feminine pronouns seldom being used. Sailors, for example, would have nothing but men and things about them for months at a time, and so it came to pass that feminine pronouns could be used to refer to anything of special significance. Thus, sexless objects like hurricanes or the ships they sailed on were referred to as “she,” and even whales, half of whom must have been male, were nevertheless so referred to when sighted, with the expression, “Thar she blows!”
However, as women began taking on roles outside the home, the English language began to accommodate their presence in a different ways. For some time, the singular “they” has been used to coordinate with indefinite pronouns, so that it has become standard colloquial English to say, “Someone left their pen on the table.” The singular “they” has become so popular, in fact, that someone is likely to use it even when they know that the person is a male.
Academics are often found using the feminist gender, as in, “A scientist will check her results thoroughly,” although the reader usually ends up thinking that a particular woman was referred to earlier and finds herself looking back a few pages to see what she missed.
And there is always the legalese alternative, as in, “Someone left his or her pen on the table,” which is grammatically sound. Given these alternatives, it is left to each person to decide for himself or herself how he or she wishes to express his or her thoughts. So far as I know, there has been no objection to placing the masculine gender before the feminine when speaking legalese, but this oversight should no longer be tolerated. Precedence must be alternated, so that half the time we should say, “Someone left her or his pen on the table.”
Finally, there is the possibility of avoiding the sex of the individual altogether, as when we use the word “person” instead of “man.” Instead of saying, “The brotherhood of man,” we can say, “The siblinghood of personhood.” On other hand, whereas it once would have seemed strange to refer to a man’s spouse instead of his wife, such a locution now serves the useful function of letting us know that the man in question is married to another man.
Because the word “sex” makes us think of intercourse, which may unnecessarily excite the imagination, the word “gender” has come to have more than grammatical significance, referring to persons instead of just nouns and pronouns. I do not know if there is a definitive list of all the possible genders, telling us how many there are or how exactly they are defined, but there seem to be more than males, females, and things, and there seems to be more to it than anatomy. As these additional genders (as a feature of persons) are a recent invention (discovery?), so too do we need additional genders (as a feature of grammar) to go with them.
However, whereas it used to be easy to discern the sex of a person, it is not so easy to discern that person’s gender. Lest we refer to someone as a man when he, she, or whatever is actually something else, a recent solution has been to introduce a new pronoun, the word “ze,” to be used in place of “he” and “she.” In so doing, the third person singular would become like the pronouns of the first or second person as well as the third person plural, which is to say, it would not be inflected for gender at all. An alternative would be for the first person singular to be inflected for gender, so that variations on the word “I” would tell us which gender a person regarded himself, herself, or whateverself, from which we could follow his, her, or whatever’s lead, but the trend is to avoid the implications completely with totally neutral pronouns like “ze.”
Exactly why “ze” was chosen as the way out when we already have the singular “they,” I am not sure. When referring to a student standing in the hallway, we traditionally might have said, “I wonder if he knows where Professor Plum’s class is.” To avoid presuming upon the student’s gender, however, we could say, “I wonder if they know where Professor Plum’s class is.” Apparently the extension of the singular “they” to such situations is unacceptable owing to the inherent plural connotation of that pronoun. Many would end up looking for two or more people rather than that single individual. And so, we are advised to say, “I wonder if ze knows where Professor Plum’s class is.”
That’s fine, except the job is not done. While “ze” is all right for the nominative or subjective case, surely it will be inflected for the other cases as well. The article linked above made no reference to these other cases, but we need something for the objective pronouns “him” and “her,” the possessive adjectives “his” and “her,” the possessive pronouns “his” and “hers,” as well as the reflexive forms “himself” and “herself.” Now, whereas “ze” is no more similar to “he” than to “she,” it is obvious that we cannot simply say “zim” or “zis,” because then we would be giving away our preference for the masculine gender. I suggest we use the word “zerm” for the objective case, combining elements from both “him” and “her.” If this is acceptable, we can then have “zerms” for the possessive case, both adjectives and pronouns, and “zermself” for the reflexive form.
Once this innovation becomes standard, we can finally eliminate the singular “they,” for we can then say, “Someone left zerms pen on the table.” But all this is just so much theory, if we don’t put it into practice. We can talk the talk, but can we talk the talk? If someone writes a blog on this website in the future, it is hoped that ze will use these new pronouns, so that zerms writing will reflect zerms desire to be sensitive to another person’s gender, treating zerm the way ze would want to be treated zermself.