Generation Gap is a post-canon alternate universe story by Richard Lobinske inspired by an Iron Chef challenge from Prince Charon: what if Helen was Daria's grandmother?
A week after her high-school graduation, Daria is told about her real mother, Anastasia, born when Helen was sixteen as the result of her tryst with the stunt car driver mentioned in "My Night at Daria's." Daria had been delivered to Jake and Helen by people claiming to be from Family Services, who said that Daria's mother and her adopted family had died and no other "appropriate" blood relatives could be located. Because of the many questions that Helen had never been able to answer in the years since, Daria changes college majors to study Criminal Investigation and Forensics, then begins her own search for what happened to her mother.
Tied for "Favorite Post-Is It College Yet?" story in the 4th Daria Fanworks Awards
"Generation Gap" at Outpost Daria (via Wayback Machine)