Re: Sex is a marketing way to sell stuff? What a news!
Gender is used as a euphemism for sex. The word "sex" to indicate male and female is apparently far too offensive for polite use. Gender is also used to classify words. "His" is masculine, "hers" is feminine and "its" is neuter for example. Of course sex is determined by the possession (or not) of the Y chromosome, both sexes (sorry for the bluntness there) possessing X chromosomes. At best if we use gender to determine type of sex (and this is using gender in its earliest meaning), then we have feminine, masculine and neuter males; ditto for females. I count six all up. Twenty three? Somebody's being creative.
The use of euphemism instead of direct speech because you are too embarrassed to say what you actually mean has something of a history.
For example, death has many euphemisms as Monty Python amply illustrated in my youth.
It is popularly supposed among feminists that removing gender-specific terms from the English will result in a more caring and dare I say egalitarian society. Instead of:
"Look at that poor woman; she has dropped her handbag!"
one would say:
"Look at that poor thing; it's dropped its handbag!"
Colour me dubious.