There IS a limit to your abilities. there ALWAYS is. That's what being human is about. Practicing is all well and good, but if you don't have the talent there's not much you can do - at least that's what most people believe. I believe that talent comes from early development. It doesn't mean that you can't have talent without early development, but with it you most certainly will. That was what my post about before 5 meant. If you start piano before the age of 5, preferably, before 4, and keep at it (so you need dedicated parents, good teacher, a combination of things) then you WILL be good. Humans are a product of their surroundings, true, but once you go past a certain age, THEN talent will dictate what you can or can't do. There are people who are wonderful musicians, who started late in their career, but have certain things pianistically that they'll never be able to do. That is a limit present for SOME late starters. Do you know of ANY pianists who started at the age of 3 and continued playing till adult life, and has a bad technique? no.
That being said, even for those who start early, kept playing, and have good, great, or amazing technique, there STILL is a limit to one's abilities. You can be the greatest pianist in the history (no names mentioned

don't want another "overrated pianist" thread here..) of piano playing and you'll STILL have limits. Hence you always try to get better, and approach your limits.
Though I will say this. Most people don't get anywhere CLOSE to what their limit is. I believe that most pianists in the world have much more talent they give themselves credit for, and are capable of much greater things than they believe themselves to be of.. um, bad grammer, excuse me.
mt