I know several families with both high attainment/well educated parents who have at least one kid who struggles big time in school. My own family included. I have 3 siblings. 3 of us did well academically, went to college, have good jobs, etc. But one of my brothers had a horrible time in school (my mom always told us that by the end of the week, my sister and I (6 and 4 years his junior) knew his spelling words for that week but my brother did not. Academics were not his thing. Wasn’t for a lack of effort on his part or my parents. Wasn’t for a lack of concern. He got into non academic problems as well (so did my other brother and sister sometimes – but never me 
). I am sure there were times when my parents at least thought (may even had said it sometimes – I just do not recall) that they would be happy if he just graduates high school.
In the end, he did manage to struggle across the finish line and graduate. College was never an option for him. He went to a trade school and does HVAC install/repair for commercial/residential. Hard, physical labor. He supports himself and is doing fine. Not clear what he will do in retirement as there are physical limits to how long you can put compressors and your shoulder and climb ladders. Doesn’t make a lot to save for retirement. But again he was never going to college much less succeeding there. Same parents (was a middle kid so its not like parenting skills/effort changed). Very different results (in huge part because different kid).