Perhaps you’ve seen some of those Italian Renaissance paintings of the Virgin Mary with John the Baptist and Jesus as chubby three-year old boys. John is usually wearing a junior version of the camel hair outfit of his wilderness years. Sometimes there’s a little lamb in the scene or John may be holding a staff with a banner that reads “Ecce Agnus Dei”: “Behold the Lamb of God.”
This is a “mash up” of the Luke story about John the Baptist and the Gospel of John’s story. It’s in Luke that we get the suggestion, at least, that John the Baptist and Jesus might have known each other, since their mothers were related. And that they may have played together as little boys. All that is missing in John. It’s in the Gospel of John that John the Baptist calls Jesus the “Lamb of God”—and that is missing in Luke and the other Gospels.