Annie, your picture of your frustrated son is part of a life story that you will look back on with joy and understanding as you see his deep character linked tosome of these images.
Doing this is directed by love and fascination.
Just like a caress, you have inherent permission to make such a record. Someone else to doing that invades your family privacy and the trust you have earned.
This is not a simple matter. After all, we" sort of" do this to adults in street photography, but hopefully in honesty and without making them react in fear!
Asher