Hello Africanus, I would say yes they can.
If they apply themselves to achieving a goal they can given determination succeed. There are limitations to this though, one cannot achieve some goals by determination alone, many things require talent and realistic goals. For instance at fifty years old I am not going to win an Olympic Gold in the 100m sprint. But at 49 I did gain a BA degree even though at school when I was younger my teachers said I would not achieve a University degree.
So to achieve a particular goal does take a deal of realistic expectation.