Originally Posted by smalltowngrll
Aaron's father was Thomas. He was an artist and you will also find that one of his paintings is in Charles Widmore's office.
I believe it was in Season 1 where we met Thomas. Remember, he was really excited about having the baby at first, but then decided he all of a sudden was not so excited about it and left. That's what led Claire to adoption and thus her being on the plane.
But perhaps he lost interest when he found out he wasn't really the father. I'm wondering if there might be some incest going on here that hasn't been revealed. It would certainly explain Jack's resistence to raising Aaron and maybe explain why Hurley/Charlie are warning him away from raising the child.
BTW, when the entire series is over in a couple of years, I'd really like to see someone re-edit this show and present it in total chronological order. It would probably need to be done as a DVD release or possibly as a syndication series.