Back in the late 70s/early 80s, the priest who baptized me got my mother and her friend into role-playing with AD&D. (As a semi-interesting post-script, said priest later got a sex change, married a man who used to be a woman, and moved out of state.) Years later, one of my friends hooked me on the HeroQuest board game from Milton Bradley. I ran games for my mom and brothers, with constantly evolving house rules as I unwittingly added role-playing elements to the game. My mom enjoyed the game fine, but repeatedly told me that it didn't hold a candle to D&D. I ended up borrowing her old RPG materials. She didn't have any rule books, but I spent hours poring over her old character sheets, wondering what a burning hands spell was or what id insinuation meant. I asked her about the map points on her old hex grids and tried to glean as much information as I could about the world.
Eventually, I saved up enough money to buy a D&D boxed set. Much to my dismay, it wasn't the same game my mom played. I had purchased the basic game; my mom had been playing AD&D (she had never called it anything but Dungeons & Dragons, and seemed unaware that she was played the "Advanced" version of the rules). So I went back to saving my money, and eventually bought the Dungeon Master's Guide (since I wanted to DM more than I wanted to play), followed by the Player's Handbook (with the Monstrous Compendium received later as a Christmas gift).
Alas, this version of the game wasn't what my mother had played, either. There were no psionics, and the character sheets were different. I had stumbled into AD&D 2nd edition, while my mom had played 1st edition. I spent a great deal of time trying to turn my 2nd edition game into the older version. This led me to purchase, among other things, the Complete Psionics Handbook. The Psionics Handbook, in turn, led me to pick up the Dark Sun setting, since I thought psionics were so cool and Dark Sun was a setting seemingly designed for them.
Years down the road, I wound up at a yard sale, and finally bought the entire collection of 1st edition books. By then, however, my interest in the game had evolved beyond what my mom played, and I was creating my own brand of fun with the game. I only wound up running two sessions of old AD&D, the highlight of which was when my brothers and I slew a white dragon with one of those fancy new polearms in Unearthed Arcana. I eventually went back to 2nd edition games, and then quit altogether for a bit after the rules bloat of the Player's Option series caused me to burn out.
Tragically, my old books all got destroyed after I moved off to college. My mother had put them in the storage shed, where mildew and mold ate them alive. I gave what books I could save to one of my friends, and eventually picked up the 3rd edition of the game. I've had much fun since then, of course. Hopefully, someday I'll be able to rope my mom into a session of D&D, and she can have some fun playing my version of the game.