<Tr> <Td> ← Previous "I Take Thee Quagmire" </Td> <Td> Next → "Deep Throats" </Td> </Tr> <Tr> <Td_colspan="2"> Family Guy (season 4) List of Family Guy episodes </Td> </Tr> <P> "Sibling Rivalry" is the 22nd episode of the fourth season of the animated comedy series Family Guy . It originally aired on Fox in the United States on March 26, 2006 . The episode follows Stewie as he battles with his half - brother, Bertram (voiced by Wallace Shawn), who is born to two lesbians after Peter donates sperm . Meanwhile, Lois begins excessive eating after Peter undergoes a vasectomy and loses his interest in sex . </P> <P> The episode was written by Cherry Chevapravatdumrong and directed by Dan Povenmire . The episode received mixed reviews from critics for its storyline and many cultural references . According to Nielsen ratings, it was viewed in 7.95 million homes in its original airing . The episode featured guest performances by Randy Crenshaw, Gavin Dunne, Bob Joyce, John Joyce, Phil LaMarr, Rick Logan, Wallace Shawn, Tara Strong, Nicole Sullivan and Wally Wingert, as well as several recurring voice actors for the series . </P>

Family guy episode where peter gets a vasectomy