According to the 2nd book of the Brinstone Angels series, As of the Spellplague, tieflings are all of Devil ancestry. They breed true no matter who the other partner is (elf, orc, human, whatever). The results of a Union between a tiefling and whoever is always a tiefling. This is why they are now considered an actual race. Their origin has something to do with the process in which Asmodeus became a God. SadisticSavior (talk) 16:34, February 13, 2013 (UTC) SadisticSavior