Great post Francesca! I have found myself wondering the same thing. I was selected for the gifted programs in the second grade, and continued in them all through my schooling. I second many of your experiences (reading special books, including the Giver, studying the brain and watching live dissections, being segregated into groups and teams/halls, etc.) I would be interested in chatting more with you about your thoughts?
When I was a teen, I expressed a type of dissociative disorder, which is generally believed to be caused by some sort of reoccuring trauma as a child. But I assure you, I had a very safe, normal, and happy childhood, and can point to no source of "trauma" in my past... which leads me to wonder about these gifted programs? Who knows, but its something interesting to think about...