Yes Jack has spent a lot of time off screen. But during some of this time, we are to understand he had no organs. Now I'm not a scientist, but I do believe it's hard to procreate when one is technically dead and organless. (Yeah, Dr. Rolf, Salem, yada yada...)
Even though he's lately had the warmth of a cold winter's night, I am here for a battle over Chad between Gwen and Princess Abs.