Lex Luthor's niece. Nasty is the daughter of Lex's older un-named sister, who eloped as a teenager to Europe and their parents disapproved and never spoke to her again.

Nasthalthia Luthor

Lex Luthor's niece. Nasty is the daughter of Lex's older un-named sister, who eloped as a teenager to Europe and their parents disapproved and never spoke to her again.

All data from the awesome folks at Marvel.