[Swanman]

One thing I read that points to Adam Warlock possibly being the dad is:

Spoiler!

In the Collector's lair, in the post credits scene in Thor Dark World you see Warlock's cocoon. Someone reported that in the post credits of GotG, the cocoon is shown and has obviously burst open. I didn't think to look for that, was too focused on seeing Cosmo again and then Howard the Duck.