I'm glad your son is happy. I think it is natural to worry as a parent, especially about things that seem very different. But these HG kids are a bit different aren't they? Normal for them, though.
When you mention your pediatrician, I remembered something else that is handy. Some kids adore their docs, and if you have one of those, this might be a good idea. Send your doc a note ahead of time that you want his/her help in getting your DS involved in something other than numbers. E.g., "doc, can you help me by telling DS how important it is to (e.g.) go outside and play." something like that. If DS hears it from beloved doc, maybe he'll listen.
And re: christmas presents. Beware! I no longer buy anything in advance for birthdays/christmas. My DS4 outgrows his passions/interests much more quickly than expected.
