<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> `` 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>
family guy episode where peter gets a vasectomy
family guy episode where peter gets a vasectomy
Sibling Rivalry
Sibling Rivalry