Rachel Dunlevy (Blair Brown) shows up in Smallville claiming to be the biological mother of Clark Kent (Tom Welling). Not only that: Rachel insists that Clark's real father is none other than Lionel Luthor (John Glover). The only way that the matter can be solved is if Clark agrees to undergo a DNA test -- which will, of course, reveal his extraterrestrial origins. Meanwhile, Lana Lang (Kristin Kreuk) has a disturbing run-in with her own real father. ~ Hal Erickson, Rovi