[kakakka]

Originally Posted by Toto y Moi

Spoiler for HxH Episode 21 Comparison:

Satotz already knows that Gon is Ging's son in the 2011 series, but not in the manga or 1999 series.

IN 2011, Satotz knew about Ging because he overheard Gon and the others talked about it while searching the internet.