This article details the family and relatives of characters in the show.
In the episode "Kids in the Hall", Kyle mentions that he usually wears cartigans, but his nana knitted a pullover for his birthday. He was originally going to mention his nana in "I, Fanbot" but it was cut for time.
Fanboy refers to Man-Arctica's mother, Mom-Arctica, in "I'm Man-Arctica!". He also mentions his third grade teacher, Mrs. Underthene.
Oz's eldery mother is first introduced in "The Hard Sell". She is known to yell a lot, and has some sort of speech impediment (pronounces W's as V's). She is known for referring to Oz as "Ozvald" or "Ozzie". Her full name is not mentioned, aside from being referred as "Mrs. Oz's Mom".
Brizwald is introduced as Oz's cousin in "Risky Brizness". Even though he seems to be like Oz, he's also sinister and snarky, and threatened to steal Man-Arctica comic Issue Absolute Zero.
In the episode "Brain Drain", Yo mentions her father gave her a transporter cell phone.