For what it's worth, having fairly short fingers (and a short pinky) has made certain guitar chords just about impossible for me, no matter how much I practice them. I will still attempt to do them in private (I'm stubborn that way), but have had to "work around" them, or find alternates, for anything I want to play in front of or with real live people. It's quite frustrating.

I have a friend who's only slightly taller than me (I'm 5'7"), but thin as a rail. He has the longest fingers I've ever seen - I'm sure his pinky is longer than my middle finger - and nothing is impossible for him when he plays his guitar. (Of course, the fact that he's been playing for over fifty years may have something to do with it!)

So, I guess I will say that while lots of practice can certainly lead to improvement, I'm still aware of things that appear to be beyond my reach (pun intended) for purely anatomical reasons.

Jay