This is a pretty damn sensitive topic for me.
Me, personally, there were never any delusions that I was going to go off into the world and do great things. I learned to walk and talk at a later age than most kids, and compared to everyone else in my class, I always fell behind. I couldn't solve math problems unless I put the equations in reverse and counted backwards until I reached the answer, and even then it would take forever. My literacy skills were okay, but nothing too special. They got me by without any hitches. Try as I might, my grades were mediocre-to-poor throughout my school years, and thanks to the Australian education board scaling back grades of "easy" subject, I technically sort-of failed high school (my overall grade score was below 50%), but I was still allowed to graduate. I'm looking to learn a trade later on in life, preferably in welding, but for now that will have to wait. Trade school's expensive, yo.
My brother on the other hand was picked as the "golden child" of the family from the get-go. He was reading and writing well before kindergarten, and breezed through school like it was nothing. He was often lauded as "gifted", and it showed. He was also the nastiest little shithead up until he got a decent social life, and now he's generally pretty calm and mild-mannered. He's also had numerous girlfriends and has been sexually active from a young age. He's now studying to become a chef.
I come from a family of overachievers. My dad's an intense workaholic who once took on three different jobs and was beating 18-year-olds in marathons up until his early 50's. My mum was a straight-A student, but since she was too poor to afford university, took a well-paying job at customs instead until she became disabled due to a car crash. And even then she was winning numerous awards for bagpiping. I've got a cousin who has two PhDs and another who's a pretty well-known musician in the Australian indie music scene. But I also have a cousin, who like me, was tested with an IQ on the lower side. My mum's openly concerned about my future, and has confided in me that she can't stop worrying that I'll never be independent and may end up homeless, abused or taken advantage of.
TL;DR, non-gifted kid in a gifted family isn't exactly the world's greatest superstar. Who knew?