While yes that's technically true it's what most people know actions that don't require thinking as so it's a convenient term. And for the record we do have instincts, we do have in-born behavioral traits. No reputable psychologist in the world would tell you we're a blank slate anymore that hasn't been a well accepted idea since B.F. Skinner was alive and active.
Here's a resource on that by Stephen Pinker, a well-respected researcher: http://en.wikipedia.org/wiki/The_Blank_Slate
also see twin studies. Our behavior is a combination of nature AND nurture, not one or the other.