In response to what I wrote yesterday, a reader questioned the effect of physical or psychological repression or abuse on the development of children with art ability. In spite of having taught children and adults of all ages for about 28 years now, this one caught me a little off-guard. Frankly, I've not had that much experience with the type of child she inquired about...not knowingly at least. Of course art has tremendous value from a therapeutic point of view with this type of child, but I don't think that's what she was referring to. In general, yesterday I was not talking about those children merely having some form of art ability. What I referred to were those with exceptional, even overwhelming art ability.
Now, from that point of view, any form of repression is, of course, going to be fundamentally damaging to the child's future art endeavours. That almost goes without saying. However, I've always maintained that creativity is not a fragile thing. That it will bloom inevitably in one form or another at some point in time. The critical factor here is, in fact, time. Between the ages 6 through 12, art, as with many other life-long endeavours, is in a critical incubation period where the child's mind and his or her manual dexterity are in a race to see which one can develop the fastest. These, I maintain, are the self-taught years--the virginal years (speaking non-sexually). Then, just before puberty, the gifted child becomes ripe for some form of concentrated outside direction. If they're truly exceptional, they will have, by this time, pretty well mastered the rudiments--perspective, eye-hand co-ordination, colour theory, media applications, design fundamentals, and developed surprisingly sophisticated aesthetic values. For all practical purposes, they are often functioning at or near the level of many if not most adult artists.
From this point on however, they are prone to what I call "rutting." They will have discovered at an early age that which they are very good at and then will have a tendency toward repeating that which they are most successful. This happens during adolescence in many endeavours, not just art, and not just with art standouts. Adult artists fall into this too, but usually much later in life when it's more appropriate to specialise. In any case, by the onset of puberty, outside art influences (classes, group or private) are now needed to jog that student out of the comfortable into activities in which, quite frankly, he or she stands a good chance of failing at from time to time. You have never in your life seen a more motivated art student than one who's just fallen flat on his or her face for the first time.
From the teen years on, the key in working with these types of kids is not to in any way coddle them. You have to be rougher on them than they are on themselves. They have to be prepared to compete with one another, not so much during the high school years (they're already well equipped to do that), but once they graduate. I've touched on this before, but it bears repeating--they have to be prepared to swim in the big pond of higher education, and eventually, once they finish college, coexist with the sharks in the really big pond we all know so well.
So, having said all that, in answer to the original question, it's never too late to overcome the past and develop as an artist. However, for the gifted child, the optimal period of art development (pre-teen), is biological/sociological, and once that is passed, it's lost forever.