they are both father and son.
if you are referring to the Mike Farrell from the MASH tv show and the Terry Farrell from Star Trek DS9 then no they're bios do not mention them being related to each...
A big NO, Colin is Irish and Will which is "John William Ferrell" is American. The name Farrell derives from, originally Fearghall in Irish (meaning man of valour), both Ferrall and Farrell are...