It is possible that Jesus knew John the Baptist, but there is no reason to think that it’s probable. Mark might have just been inventing a pericope that showed Jesus was greater than John the Baptist, the way Matthew invented material to show Jesus was greater than Moses. There is (possibly) a heavy lining of haggadic Midrash in the gospel of Mark. Mark says “The beginning of the gospel of Jesus Christ ; as it is written in the prophets.” Mark immediately interprets John the Baptist as a forerunner of the Messiah (a la Elijah in II Kings 1:8). Mark then clothes John similar to Elijah (Mark 1:6. II Kings 1:8.) He then says John ate locusts and wild honey,the food of the wilderness in which Elijah lived (and so on and so on). Perhaps the baptism of Jesus by John is meant to reflect 2 Kings 2 near the Jordan where Elijah bequeathed a double portion of his power to Elisha, making Elisha his successor and superior. Maybe later writers misunderstood this as a historical event, and because it was already understood that way in their communities and so couldn’t deny it, they included it as an embarrassing event that had to be explained away. Just because later writers were embarrassed by it doesn’t mean Mark was, or even that Mark ever meant for the pericope to be taken literally.