Laharl's mom was a redheaded human witch who came to the Netherworld to advance her study of magic. Krichevskoy fell in love with her at first sight.
The story of Disgaea takes place in the distant future, judging by the level of Earth's technology (and Gordon being the 37th Defender of Earth), but Laharl himself is more than 1200 years old at the story's beginning.