I've wracked my brain, sure that I had introduced someone to D&D back in my childhood. The only names I can come up with were jocks who would have had no interest in playing or kids like me that already were playing. Same in high school: everyone that I would have introduced were already playing.
Fast forward to the 21st century, when I picked up the dice again. There was a relative newbie in the group. I know he'd played Robotech before, but I cannot remember if this was the first time he'd played (and so would qualify as my first introduced, as I was a part of the group that introduced him).
So, I think I have to count my oldest four children as the first
Cast of Characters
Lanin: elf wizard (17-year-old daughter)
Carn: human rogue (15-year-old daughter)
Regdar: human fighter (13-year-old son)
Dothal: dwarven cleric (9-year-old son)