Jay - suppose you were observing an athlete performing a skill, say it's throwing a ball to someone a long distance away, and saw that the athlete performed the skill very effectively. How would you discern how much of that performance was acquired behavior vs. natural ability?
The answer, of course, is that you couldn't. You need historical information to make that determination. It's not a performance based distinction, while skill inherently is. Did the person throw the ball with sufficient power and accuracy?
Some athletes are more naturally gifted the first time they pick up a ball or whatever. Of course they learn and get better at it from observation, teaching, and practice, but there are innate advantages and disadvantages across individuals - i.e. ones idiomatically describable as being "from birth".
(Bonus word nerd point: When we speak of "natural talent", we're using a term that came from root words meaning, "from/by birth":
natural | Etymology of natural by etymonline )