More than 20 years ago, I played a MUD where, when you typed text to other players, it would automatically capitalise the first word of the first sentence - and only the first word.

I have no idea why, but this permanently changed how I type whenever I'm typing a message and not really thinking about it. I drop the initial capital, but hit that shift key for any subsequent sentences.

I didn't even play the MUD for all that long! But I can remember crystal clear adapting to that pattern and then never changing back. I don't get it at all