In Rick and Morty season 2, a major part of Rick's past was revealed via a picture of him holding what appeared to be a baby Morty, yet he seemingly has no such pictures with Summer. Even Rick's backstory at the end of season 5 gave no new clues about this mysterious photo. Originally appearing in season 2, episode 5, «Get Schwifty,» Morty saw this picture on a wall in Birdperson's home after a conversation about whether it was ever worth putting any faith in Rick when he's always so reckless and selfish.
While Morty asked Birdperson who the baby in the picture was, he was interrupted before he could get an answer due to Rick needing help with the alien talking heads' ongoing threat against Earth by way of an intergalactic musical reality show. This showed that even after season 5, Rick & Morty is still filled with a great number of unanswered questions, with the origin of this photo being one of them. Many Rick and Morty fan theories have focused on the photo, making it clear that there's no shortage of speculation when it comes to this particular mystery.
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There was even a time when theorists speculated that the Morty in the picture was from Rick's original dimension, and that dimension never had a Summer, though that wouldn't be possible due to season 5's revelations. While it's true that Rick's original dimension never had a Summer, it also never had a Morty due to Beth dying as a child. While Rick and Morty season 3 implied that Rick made this up to trick the aliens who imprisoned him, it was revealed that this part of Rick's past is true in season 5. Knowing that Rick's grandkids weren't from his dimension, the question of why Rick took a photo with baby Morty
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