And the Baby Momma Is ...

I couldn't be more embarrassed that it took me all of a week to think of this as it is so completely obvious. Penny is Jack's baby momma! Who do we know that runs a tour de stade? Jack!

Picture this: 1989. Penny and Jack are married and she's just given birth to a son. He's like, "I have an idea for how you can drop this baby weight. I like to run up and down all the stadium stairs behind the hospital. So why don't you bring me dinner (have a lettuce leaf yourself) and then go run the stairs." And she's all, "Bullocks to that. Why don't you go take some more pills!" And they split up. But then she's back in the dating world and ends up taking his advice about the stadium stairs. And she's been rockin' those stairs for the last 15 years.

Which would make David Shephard Widmore's grandson and heir-apparent to the Widmore empire. It would also make Widmore Jack's ex-father-in-law. I love that!

Another clue: David Shepard plays Fantaisie-Impromptu in C-sharp minor by Frédéric Chopin -- the same song Daniel played in his flashback. In the flash-sideways Daniel is a musician. He lives in the same city as his half-sister. He could have easily taught his nephew this piece.