didn't the one that forced him to attend the shows was a caretaker at the orphanage? if I'm not mistaken, he's already an orphan at the time
Remember that Gio had the illness all his life.And also in the episode where 6yr Gio meets 3yr Felix, he was already in the orphanage and getting abused.It was the caretaker of the orphanage who forced him to go to the shows and the reason why he acts like the burns don't hurt.The caretaker used to think he lied about feeling pain because of his illness. The other children at the orphanage bullied him too.
Also I'm pretty sure Leegang and Gio are full brothers, Leegang being the younger one. So in conclusion Gio's dad wasn't abusive.It was the orphanage caretaker.
So we have this other person that looks like Gio, I forgot his name so we'll call him Dio heheh. Anyways, In chapter 123 we see a picture of Gio. So what I think is that they're half brothers, but then again, how did an abusive father turn into a goofy fella?(if you forgot, Gio was forced to attend those show by his father, the reason why he gets cold easy and don't feel hot) then again, we don't know the mother, so I'm thinking the lady on the pharmacist is the mother :D