One of the secret strengths of Futurama was the surprisingly tight world-building that was slowly revealed over the years, with everything from cosmic revelations to familial discoveries often serving as equally impressive plot twists. However, there was one four seasons in the making, as in the show's fifth season, Futurama revealed that Igner was secretly a member of the Farnsworth family -- and therefor a direct descendant of the show's main character, Fry.
Igner first appeared in the Season 1 episode "A Fishful of Dollars." One of the three sons of Carol Miller -- aka the cruel global powerhouse known publicly as Mom of Mom's Friendly Robot Company -- Igner is often seen at her side and taking part in her crimes. However, especially when compared to his brothers Walter and Larry, Igner is far less malicious. This may be in part due to his lack of intelligence, which repeatedly leads him into slapstick antics that his brothers can somewhat avoid. He's also the only one of the three suggested to be genuinely sweet-natured at times. This element of the character resulted in Mom's ex-lover Professor Farnsworth growing to despise Igner for his lack of intelligence, finding it almost personally insulting how stupid the character was.
However, their true connection was revealed in the Futurama Season 5 four-part episode "Bender's Game." During that set of episodes, Igner overhears his mother discussing a secret about his birth with his brothers: it turns out that while Walter and Larry are implied to be the sons of Ogden Wernstrom (Farnsworth's former student and consistent scientific rival), Igner is actually the result of a brief flare-up of the romance between Carol and Farnsworth. In reality, Igner is Farnsworth's biological son -- meaning he's also a direct descendant of Fry. Due to this discovery, Igner becomes an ally to the Planet Express Crew during their attempts to claim the "Die of Power" and prevent Mom's continued conquest of the fantasy realm they were all trapped within.
Farnsworth was furious during his confrontation with Igner until he discovered the truth, and working together the pair were able to undo Mom's plans and render her black matter-energy reserves useless. They even shared an embrace as father and son. However, Igner didn't play much of a role in the rest of the series, as he again primarily served as an aide to his mother and brothers. It could have been a fun development to see the rest of the Crew deal with this revelation -- especially Cubert, the clone of Farnsworth that served as an infrequent son figure for the Professor.
It's possible his lack of intelligence is an indicator that -- like his distant ancestor Fry -- Igner lacks the Delta Brain Wave, which has been suggested to be one of the chief reasons Fry, despite his lack of intelligence, was able to save the world from organisms like the Giant Brains. Even just having a voice in the Mom's Friendly Robot Company that was an ally to the Planet Express Crew could have set up some interesting new storylines. As it stands though, it's still impressive to consider how Futurama -- which had previously hidden Leela's true birth parents and the full circumstances of Nibbler's connection to Fry in early episodes -- was able to effectively do the same with Igner.