Hello singersgirl, I haven't seen (= been on the same thread as) you for ages! Hope all is well?
This is not really with ref. to my children but to specially clever people in general, which I've been lucky enough to be surrounded by just about always. (And at the same time by people who are thoroughly bright, but just not in the league of the special ones. So I've seen the difference every day.)
And the difference is chemical. You know those children who can't stop talking, like they're human Perrier where the speech bubbles form and form and cannot BUT collect rise burst & TALK? And while one bubble is rising and bursting endless following bubbles are endlessly following?
Truly gifted people are like that - it's not just that they're self-starters: they can't NOT self-start, they can't stop self-starting, it's not in their nature. It's a state of intellectual inspiration that just keeps renewing itself.
What I think is quite nice is that sometimes that quality emerges later than early childhood - most fizzy-brained people probably show themselves that way from early on, but some find themselves later. (And, of course, some quite able people/children level off eventually because, in all final truth, they aren't fizzy. I'm one of those, I think.)