My parents gamed on a Friday or Saturday night, and they took us with them. (My sister, pre-crawling, was once stood on by a DM, but that's irrelevant.)
We'd usually sit around and listen, or read a book, or whatever, until we got tired, then crash behind a couch or something. (The games usually went until about 1am.) I credit those early experiences of sleeping in brightly-lit rooms with people talking and laughing with my knack for being able to nap anywhere today
By the time I was five, I was well-familiar with the three 1E Core books... I had the casting time and duration of pretty much every spell in the PHB memorised, along with the standard equipment tables (though we never used weapon type vs AC adjustments, so I didn't learn those
). My parents' group would frequently ask me, rather than bother looking something up.
When I was 6, my mother ran me through a cut-down, solo-modified Palace of the Silver Princess.
And after that, I joined their group.
I look back, and think "How could a bunch of late-twenties gamers have tolerated a
six-year old in the group?" One of my players, a couple of years ago, had his twelve-year-old son join our group, and it just about drove me nuts.
But I'm assured that at six, I was a better player than this 12yo, and that it wasn't really a case of 'tolerating' me.
I'm not sure I believe them... but nevertheless, I'm forever indebted to them all for even considering the idea in the first place
-Hyp.