The more intelligent child will be intelligent because the child doesn't just take new information for granted and thinks about it. A child might even overthink things like pain. The child might on one hand decide that "pain" is nothing more than another stimulus and that the mind can and should learn to coexist with and be happy with it, but then the child may then think "but what if this causes me not to notice pain enough and then I get hurt and don't notice" and then respond by obsessing over the smallest physical discomfort, which in time would turn into a pain problem.
I believe intellience and enviorment co exist when it comes to pain problems as an adult. It has been proven that enviorment plays a role in intellience. For example, my parents told me all my life that I am attractive and stupid. I believed what they told me for over 30 years. I broke away from my parents, and went to school. I have been making straight A's for the past three semester and have a 3.81 GPA. The point is that someone can be very intelligent and not believe it which can lead to problems in adulthood!
An intelligent child will likely result in a bored child, who will likely result a lonely child who looks at the world through sad eyes and only sees negativity and pain. Too much focus on negativity and pain will undoubtedly result in stress and weakened bodily defenses, not to mention imagining to fruition one's own pain problems into adulthood.
Yes, intelligent children go through experiences in life which may cause pain in adulthood that average children may not. However, average and especially low intelligence children go through their own unique problems which can cause them pain. Everyone has to experience pain in their lives and being intelligent does not exclude people from this.