I think they were hinting it in episode 12 when kangjoo said so that's how real father son are alike and i noticed kangjoo's mom often points it out too. 

I do like the idea of that because I'm curious what would happen.  I think it could be a good opportunity for KangJoo  to get a closure & let go of his attachment issues plus his fixations on the idea that him & his father should have similarities to prove their relationship. Can't guess whether it would hurt him or give him satisfaction, ( I personally think it would hurt him) but I'd really like to see that happen & I believe there could be a chance for his appearance.

I believe his father already appeared on screen. I found a particular character very much alike Gangju in terms of appraraance. You know the men that helps his mother to find his money? For some reason I believe is him beacuse they really look so much alike. 

Since KJ has a different last name than his mother or stepfather, I’m assuming it’s his father’s name.  Therefore, his father had to have been in the picture when he was born, right? 


maybe but I don’t think so. And if he does I think he will close the chairman even though he divorced his mother