Hi everyone! I know there are some huge genealogy buffs around these parts, so I though it might share this here. In the 1970s, the French published Le Manuel de Géo Trouvetou ("Gyro Gearloose's Handbook"), which contains unique information about his family. I know this was translated from a Brazilian original, but I don't think it's ever been published in English.
So, you have Géo's uncle Jojo Cherchetou (the last name being a pun on "cherche tout," i.e. "looks for anything"), and Jojo's own uncle Oger Toutrouvé (a pun on "oh, j'ai tout trouvé !" i.e. "I found everything!") I will, at some point, translate the full text, but basically it says that, as a child, Géo/Gyro went to live with them for a time, in a boring little town called "Monotonopolis"---until they were all expelled.