Not the most common name (Janssens & Peeters), but rather common : -3683 Goris in Belgium, mostly in the northeast of Flanders, dutchspeaking, in Antwerpen and Turnhout(B). A lot more in the adjacent province of Noordbrabant (NL). Very rare in the West, coastal Flanders, and the South, Frenchspeaking Wallonie. -only 8 Ghoris (origin a drunk father misspelling the name of his child to the City Hall clerk in Gent) -etc... see www.sopress.be and click on the belgian map somewhere in the middle.
All Flamish and Dutch Goris (and Ghoris) should be related, if traceable to the small region just North-East of Antwerpen (Ekeren(B), Zandvliet(B), Ossendrecht(Nl), Hoogerheide(NL),...) Kinship might be up to 3 centuries ago for some branches though. In some of those villages it was the most common name. Gooris, etc. is also allways related, I guess, but do not know for sure.