Jingle Bells Mystery

So Jack really likes singing. Really, really likes it. And I must say he's pretty good at it, for a 1 year old! He picks up on songs so quickly that every once in awhile he'll be singing a song that we have never even taught him. The other day it was Jingle Bells. Now, we've sung Frosty the Snowman, Rudolph, Silent Night, Santa Clause is Coming to Town, but for some reason or another I had not taught him Jingle Bells. Yet he was singing it... We asked around (Grammy, Sunday School, etc.) and no one had sung Jingle Bells with him. How did he learn that song?! Then, yesterday we were watching Elmo's Happy Holidays DVD (which by the way teaches about Hanukkah and even Kwanzaa, but that's a whole other topic) and at the very end, the cast sings Jingle Bells. He's only seen the show all the way through twice before! How did he do that? I'm amazed! And I can't stop thinking about the big decisions he's going to be making one day- sign with the record company or the NFL? Or finish his degree at Harvard? Hmmm...