In the 1970s, a small number of people got all het up about language, and we got a lot of terms like "fireperson", a sudden surge in slash usage (s/he, his/her), and the beginning of quite a lot of other pronoun nonsense, especially people being so afraid to appear sexist that they began to use plural terms where a generic "he" or "his" was called for ("Anyone wishing to survive the crash should put on the lifejacket stored beneath their seat. Anyone without a lifejacket may wish to put their head between their legs and...") A lot of the anger among the very few people in the population who actually cared was over the fact that English uses a male term as the generic--"mankind" rather than "personkind", "his" rather than some sex-generic term like "shis". That "man" can refer to a male human or to everyone, while "woman" can refer only to a female (or, more rarely, to females generally) but never to humanity as a whole, was supposed to be offensive.
I'm a child of my time, so I understand what they were saying: "The male is made the standard of all things, etc." But really now, couldn't it be interpreted exactly the opposite way? "A man is just a man, but a woman is something else! WOman is man-plus, man the deluxe model, man with extra. We say 'his'or 'he' for people within mixed groups, because while anyone can fit the basic model, not just anyone can be the luxury model."
Well, it makes as much sense as what the '70s language police were saying.
I'm about to go off to have my dinner, but it occurs to me that there's another oppressed group whose concerns the gender-in-language people were not concerned with: the animals. Won't somebody please think of the animals?! Language tradition wasn't much concerned with them either. How else do you explain the fact that there is no way to refer to members of a mixed humans (both sexes) and animals (both sexes) group? If I wanted to say that all the members of a mixed household were about to have dinner, but I started off with a singular term, how would I continue? "Each member of the Jones household is about to have her/his/its dinner." Rather awkward, don't you agree? So far the only non-sex or species-specific terms I can think of to substitute are "shirts" or "shits"; as the former may be somewhat more appropriate, I propose we use "shirts" for "her/his/its" and use "sheet" for she/he/it. I leave the question of why the Jones household is called by the name of its human oppressor rather than by the name of one of its animal members to someone else.