My parents are gamers. They started playing 1E AD&D in the late 70s. They played on a Friday or Saturday evening, weekly, from 6ish through 'til midnight or 1am. My sister and I came along, and would sit up listening until we got tired, then crash behind a couch or something. (Not sure exactly when I was first taken along, but I know my sister was present when she was only a couple of months old!)
The nights the game was at our house were the best - the next morning, my sister and I would wake up early, and come out to the living room, where all the leftover chips, sweets, and soft drinks were yet to be tidied away...
I started reading the 1E Core books, and by the age of six had them effectively memorised (even if I didn't know exactly what a 'brazen harlot' was

). My mother ran me through a solo version of Palace of the Silver Princess, and shortly after that, I joined my parents' group.
(That's right - a bunch of mid-late twenties let a six year old play. I still don't understand what they were thinking! But apparently (I'm told) it wasn't much of an issue...)
It wasn't long before people stopped looking up spell ranges or durations at the table... they'd just ask me
-Hyp.