Acting: Nature or Nurture

I've often wondered, there's quite a few actors who followed in their parents' footsteps and they usually turn out to be decent actors. People usually say 'oh, they inherited the acting gene' but I wonder whether it's so much genes as the upbringing by the parents that made them to be potentially good actors. I mean it's quite logical if the parents themselves were brought up a certain way then they would bring up their children in that way too, therefore paving the way for their children to be good actors too right? Or could it be really in the genes and whichever way or whoever brought them up they would still be good actors? Hmm, I guess it is another example of the age old nature vs. nurture argument that no one can really prove conclusively...