He has been praised and adored by us from day one. He is the first grandchild on both sides so he can do no wrong in anyone's eyes
. We tell him all the time that he's amazing and that we love him. We are strict and have very high expectations of behaviour and manners, but not in a scary way iykwim.
And yet still his confidence in his own abilities is so low. Why?
It affects hs school work. He doesn't like committing to answer just in case he is wrong. He's always been that way 
Latest example (which may sound small to you but it frustrated me) - this morning he told me that he'd placed himself in the middle group for the forthcoming swimming lessons in school, this being the group 'for those who struggle to complete a length of the pool', despite having spent four years learning to swim very well and completing all the levels at a different pool. And he's very good at anything sporty, in fact it's one of his strengths, but still he won't see that in himself.
What on earth more can we do for his self confidence than we already do? Is this just nature, not nurture, and is it even possible to meddle with it? His 4 year old brother has ten times his self confidence and thinks he rules the universe.