I find this interesting with a 2e pg son and thinking about the childhoods of people such as Stephen Hawking and someone who I knew briefly that worked at a very high astrophysics level (ie. helped discover the Higgs Boson and worked at the CERN, etc.).
This reminds me of my brother who is a high energy physicist and is always going to CERN. I just saw a photo of him on facebook having a casual dinner with two physics nobel prize winners.
Nothing remarkable at all about his early development, as far as I can recall (though I am 3 years younger). He was always a good student and I remember he liked to break into places and pick locks just for fun. But he talked, walked, read, etc. at normal ages. In fact, I think he was delayed with a lot of motor skills and never got into sports at all. Fits the stereotypical clumsy geek image in that respect. My DS seems to be following in his footsteps and looks like he will be very good at math (he doesn't get it from me!). He is also poor with motor skills. I wonder what it is about kids who are very mathy or geeky being on the clumsy side of things. I think there is something to the stereotype.
