I doubt anything's 100%. Partial is the key word here. Yes, some
   things are genetic. But... not all things.
   I find that to be a very important thing to not forget.

   Pure reason may be a myth, but I believe the
   "all-thoughts-are-predetermined" is equally mythological.

   We're trained poorly and frame the question wrong. It's not
   Nature or Nurture. it's Nature AND Nurture. Always has been. The
   first three words in your sentence though, say it all:

   "I would say".

   Perhaps the difference is in the understanding of what the
   "free" in "free will' means.'