Until Ohr Jen Ngok and the former Jin Empire thugs Sa Tung Teen, Pang Lin Fu, and Ling Tze Seung Yan revealed to Yeung Gor the truth about his father Yeung Hong's life of villainy, Yeung Gor lived with the illusion that his father was a good, righteous man who had been betrayed and murdered. That's understandable: no son would want to believe that his father was scum.
Nevertheless, didn't Yeung Gor suspect something was wrong with Yeung Hong even early on? Yeung Gor's mother Muk Lim Chi refused to discuss the subject of Yeung Hong with him. Gwok Jing and Wong Yung, whom Yeung Gor knew to be good and trustworthy people, were unable to give him a straight account of what happened. Yau Chui Gei wrote the epithet "unfilial student" on Yeung Hong's gravestone. Most significantly, nobody wanted to talk about Yeung Hong, much less honor his memory. This must have tipped Yeung Gor off that *something* must have been wrong with his father, even if he didn't know all the details. Do you think he might have subconsciously known (or at least suspected) it all along, but couldn't bring himself to face the truth until he had incontrovertible evidence?