While going through the Baby's clothes that he has outgrown, the kids discover that the nest that the Baby's egg was in has a note, "Property of Gus and Glenda Molehill". Fran remembers that there was a Glenda Molehill in her La Ma's class, and remembers the time there was an earthquake, which caused the eggs to role out of their nest (and the two were unsure if they had the right egg). Earl, who's been abused by Baby so much, decides to call up the other parents to see if they were switched. The Molehills look closer in color to the Baby (the only one of the Sinclairs who is not green), Gus has a personality very similar to the Baby's (along with the same catch phrases), and their baby, Aubrey, is green and wears a shirt like Earl's. Gus takes a liking to Baby, while Earl likes Aubrey (who, in contrast to Baby, is very polite to Earl). Fran, however, remains unconvinced until they get some Absolute Proof. They go to Absolute Proof Labs and do a DNA test, and the results show that Aubrey is indeed the son of the Sinclairs, while Baby belongs to the Molehills.
Earl is the only one who is really happy with Aubrey. Robbie is annoyed that he keeps bleeding, Aubrey feels unsafe with all games they play (even a simple game of "Where's Daddy?", and Fran can't find the sugar-free tofu teething cookies that Aubrey needs. She is especially unhappy that it's the Baby's birthday and she's not there to spend time with the Baby. Fran soon decides that she wants her baby back, even if science proved otherwise. At the same time, Glenda shows up, appalled at the Baby's behavior, and wants Aubrey back, while Gus still prefers Baby. While the fathers want the other child and the mothers want the child they've always known, Robbie suggests they settle things by seeing Solomon the Great.
Solomon the Great is a judge who uses magic to determine things. He decides to cut Baby in two, but right before he does so, Earl decides that baby is his child and doesn't want him cut in two. Solomon still cuts him in half and gives each half to a different family. Since Gus doesn't want half a kid, he gives his half to the Sinclairs and decides to keep Aubrey while he's still in one piece. While Earl is happy to have the whole Baby back, even if it's two halves, Solomon decides that he's shown he's a true parent, and magically puts Baby back into one piece. Afterwards, Earl says that he's still a little bothered by the fact that science said that the Baby is not really their child, which Solomon sees as a request from the audience, and brings in the scientist from the lab, who reveals that there was a mix-up in the lab the whole time.
Includes examples of:
- Bait-and-Switch: When Earl tells the Baby that his first birthday party will include a pony, the Baby acts excited... But rather than have the pony to ride, the pony is to eat.
- Birthday Episode: This episode takes place on Baby's first birthday.
- Enfante Terrible: Glenda Molehill can't stand Baby after a single day.
- File Mix Up: At the end of the episode, it is revealed that there was a mix-up with the tests at the laboratory, proving that Baby does in fact, belong to the Sinclairs.
- Meaningful Name: Solomon the Great is named after Judge Solomon.
- No Celebrities Were Harmed: Robbie watches a music video by Lyzard Skyzard.
- Special Guest: Jason Alexander as Gus Molehill.
- Status Quo Is God: The Sinclairs get their baby back, and they learn that the labs mixed-up the test results.
- Switched at Birth: Both the title and premise of this episode.
- We Want Our Jerk Back: Aubrey turns out to be so cloyingly sweet and agreeable that the Sinclairs want Baby back and send Aubrey back to his family.