not a martian, honestreading through some old Knights of the Dinner Table strips I came across a few instances where people had problems with players playing characters of a different gender than their own.
Now I know #kotdt is satire, but satire often contains some truth. was this an issue for some people in the 90s? is that an issue for people now?
for the record my very first game involved a genderfluid player character way before I knew there was a word for it, and my own characters are about 50/50.
I never saw that as something to even think about. but I also always assumed that roleplayers were bound to be more progressive and egalitarian than some of the people I encountered later on
Demi 
@kyonshi I've never had it happen at my tables, but I've heard of it online. So maybe? Probably, people are people, so someone out there's upset
Dare@kyonshi This was definitely a thing in the 90s and I think also in the 00s. Fortunately it's been ages since I last ran into it.
Hteph@kyonshi In the late 90's or early 00's I was outright forbidden by a GM (or actually a ST) to play a character of the opposite gender. So yes, there was something in the air back then.
Phillip McGee@kyonshi
I saw it frequently in the 80s and 90s. The biggest problem I remember from that time was that people would do it and play to whatever stereotypes that they favored. Which caused a lot of tables to ban the concept of playing different genders.
I haven't seen this behavior in decades, but that could also be that I've been playing at better tables.
Glen Mastodon ☠@kyonshi I remember a forum post from early 00s asking people about playing different genders. Most people were completely fine with it. One guy said something along the lines of "I play a man when there is actual story, but if it's just a silly hack and slash, I sometimes do play a stereotypical hot action woman". I don't know why that reply stuck with me
Cocaine Owlbear@kyonshi alright… I'm a cishet male (he/him). I've always been very secure in that. And I'd say fully 90% of the characters I play just… aren't. Most recently, in my Scion campaign, I'm playing a non-binary half-gumiho hacker.
It was never an issue in my head. The folks at my longest running table used to roll their eyes a bit back in the 90s, but nothing serious.
I've heard of people being gross about it, or people getting mad, but it's never happened at any table I've ever played at.
Fennix 
@kyonshi The film Gamers: Dorkness Rising kinda captures this well. One of the main characters is a guy playing a high charisma sorceress and constantly forgets this mostly for comedic effect.
I recommend it as the main example of a TTRPG movie done well as the way it is shot is about the campaign, and people playing rather than the characters and it reflects that very well.
Damien (TIG BUSINESS)@kyonshi in my experience any issues were mostly just people doing it badly - playing hard into cliches or doing bad squeaky voices .
I never played with a group when anyone caused trouble over somene playing different genders,at least out loud. I do it about 1 time in 4, when the idea works better. Plus, you know, all the time as a GM :)
Derek Guder (he/him)@kyonshi “That GM doesn’t allow anyone to play characters of a different gender” was always a thing that was _out there_, but I typically used it as a quick test for “probably not going to gel with that table, so I’ll play with other folks.”
Games People Play@kyonshi Please NEVER diss players of genderflip characters, many eggs actually find themselves via roleplaying games, I've seen it happen more than once.
Having said that, while things get awkward when a player gets creepy and pushes advances IC into other players, this would still be true even if player and character matched gender, so the problem here is not a genderflip characters, it's inappropriate creepers with no notion of time or place.