Some kids are pretty obvious, ie reading by 3.
Others, not so much, especially in minority communities. A lot of parents do not follow the kid's lead, so the kids will catch up when they get into school, if it is a good school. And many people are not perceptive about kids' behavior.
If a kid's parents were smart, but were castigated for it, and them developed bitterness towards intellectual activities, then they more than likely will share that "wisdom" with their kids.
Intelligence is like a seed. It needs a good environment to reach its full potential. If it finds drought and poor soil, then it will always remain stunted.
Early development of intellectual faculties is the "early development" one would look for. Learning to walk early may be easier for high IQ kids, if that is something they want to do. But wanting to sit and read a book will not build coordination. A GT kid will have more interests and spend less time doing gross motor stuff.
Again, given the risk factors, IMHO GT is something doctors should screen for and talk to parents about to ensure that parents get the needed info.
