The
offspring of
genies and
mortals in the
Planescape setting from
TSR, the
genasi are one of a number of
races that are partly
supernatural in the
game.
Tieflings and
aasimar are of the same
sort, and
half-elves might be considered the
original kind.
Addendum: In
Dungeons and Dragons Third Edition, the basic statistics for
genasi appear in
Monster Compendium:
Monsters of Faerûn.
Character Creation rules for them are in the latest
Forgotten Realms Campaign Setting.