The Simpsons season 21 episode 8
Episode title: Oh 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.