The Simpsons (1989): Season 21, Episode 8

21 - 8: O Brother, Where Bart Thou?

One snowy day in Springfield, Lisa informs Bart that she and Maggie share a bond that Bart will never understand because he doesn't have a brother, so Bart asks Homer for a baby brother. When Homer denies Bart's request, Bart makes his way to the Springfield Orphanage to find what he thinks he's missing.