No, but Colin Baker is actually somewhat related to Patrick Troughton, in a way. To be exact, he was and likely still is best friends with Patrick Troughton's son, David Troughton. The relationship may actually be closer than that, he could be Patrick Troughton's nephew; many of the actors who work for the BBC go by stage names and even sometimes obscure the real identities of most of their families besides their spouses and children. For example,Sylvester McCoy's real name is Percy Kent-Smith, and Peter Davison real name is Peter Moffett. But we can't confirm this, so as far as we know, Colin Baker is a close friend of the Troughton family and is by no means related to Tom Baker.