1995/m here and I exclusively use dark mode. Preferably white text on a black background (sometimes called LED dark mode). I'm not sure if your generation + gender theory holds but I will say that the games and software I played growing up used a combination of dark and light for UI and menus.
Female, born before 1980, prefer dark mode, no wallpaper.
I find that most apple users i know use light and android users tend to use dark. Apple users care less about customisation maybe? I was excited to finally get widgets on my work iPad. I told several apple friends about it and they just looked at me blankly.
Millennial woman here. Dark mode all day every day, but I'm also able to keep my office fairly dim. Unfortunately the main program I use for work doesn't have a dark mode option.
Gen X woman here, I started using dark mode a couple of years ago when I was really suffering from Long Covid, and using any kind of screen was a trigger for fatigue so bad I'd need to go lie down and sleep before I collapsed. I read up on managing screen work with fatigue conditions, and dark mode was suggested. As soon as I tried it it was like loads of noise went quiet in my brain, and it just felt calmer. I also suspect I may be autistic and / or ADHD and this may also be a factor. I have to have everything on dark mode now, light mode just feels so shouty and loud.