From my experience, people generally don't know. The evidence is all over this forum. Unfortunately, when they do finally know, they disappear from these gifted forums, stop seeing the gifted specialists and no longer show up at the groups they once attended. For this reason, people rarely get to know the long term story.
Brain development is not something that ends at birth or even an early age. The ability to perform well on simple questions on a test at an early age is not an indication of an ability to later perform well on more complex questions at a later age, even in the same subject. Having a large vocabulary or doing well on a spelling bee is not an indication of all around good communications skills.
All a person can really say is a person is gifted at a variety of very specific skills. This can be said about almost anyone. Some of these very specific skills lend themselves well to the academic world, yet may not really be an indication a person will be very skilled in the practice of their field of study.
I do believe labels are useful for the purpose of communications, but the label gifted is not one I particularly like. Most of the time, gifted assessments are based on very simple skill testing. Sure performing these skills at an earlier than normal age is interesting, but does not necessarily mean what a lot of people think it does. Getting too caught up in this gifted label can lead a person to make a lot of wrong future assumptions, expectations and possibly lead to denial when these expectations suddenly don't manifest themselves.
