DS1 definitely not average. Looks highly likely to be dyslexic, possibly other areas of neurodiversity. Still struggling to write his name accurately at 8 (tinted glasses helped to crack reading in y2), but we have really in-depth discussions and he understands ideas to GCSE syllabus level. At 5, I had to bring him into my school and I ended up getting him to explain an idea to my GCSE students that they were struggling to grasp! He either excels or struggles with things. Very little middle ground. On G&T and SEN registers 
DS2 is "bright" at least age expected or above, mainly above. Not the greatest writer at present, good at maths. Very sociable. More resiliant than DS1. As long as he puts in a decent effort at school, he should do well as a foundation to adult life. DS1 is harder to predict. His niches are towards careers that are lucrative. Exam pressures could be interesting...
Having taught around my county and in lots of small towns where education isn't valued or celebrated, yes, my DCs are above average nationally. Statistically, they should be against factors like maternal education, access to books etc. Being "average" in their class (state school) is a good place to be, as there is very little disadvantage, and their parents have sufficient education, skills or work ethic to put them within the catchment area.
MN is a self selecting demographic. Virtually all posters are articulate and display a decent ability to express their ideas. To be on AIBU, you do have to have some curiosity and world awareness, so I would expect a bias of above average children from people responding. The writing in The Sun or The Mirror is pitched at an average level of literacy and understanding.