Here, I'll start. When I was 8 years old, my parents went to a dinner party and plonked me down in front of the host's computer so I'd stay out of their way. The game they booted up to keep me occupied was Space Quest II. Little did they know what impact that would have on me...
The first adventure game I bought and played was an Infocom interactive fiction ... I think it was Stationfall. Before I had briefly played Magnetic Scrolls' Fish! at someone else's computer. Fell in love with text adventures and started collecting them, I have a few of the Infocom folios as well (sadly not the Starcross saucer). The first graphic adventure I remember playing was King's Quest IV.
These games, along with later games like Monkey Island, had a huge influence on me, I learned programming to write adventure games myself but spent more time writing adventure game engines (both text and graphic ones) than actual games, and today I'm a software engineer (not in the game business).