I think so many factors are in play it's difficult to know what the answers are. Sorry this is long!.
Both my parents came from really poor backgrounds (really big families), both left school at 15 with no qualifications and got married at 19. At that time my Dad was working down the pit and my Mum worked in a supermarket. They had me and my brother in their early 20s.
We lived in a deprived area and my brother and I were quite bright and the local primary schools weren't great. This was the 80s and private schools did have scholarships available and my brother and I did entrance exams and were offered places at good private schools for secondary. My parents did have to pay an amount and they worked all hours to pay and we didn't have holidays or a car etc.
My Mum and Dad were basically told they should 'know their place' by family members and I did have a hard time being the 'poor kid' in a private school. I feel terrible saying this now but I never had friends over because I felt embarrassed because we lived in a council house and they all lived in huge houses. I was the kid with the second hand uniform who could never afford to go on all the school trips abroad.
I am the only person on both sides of my family to get a degree. I decided to be a Nurse which did cause my parents a bit of disappointment as they wanted me to be a Dr or a lawyer!.
Some of my cousins work and do ok for themselves but some are in and out of prison, have drug or alcohol problems and one died a few years ago of a heroin overdose.
We ALL came from the same gene-pool and the same background so what was the difference?. I do think a lot of it was our differences in education but not just that. Going to a private school was hard for me but it was a privilege and it WAS just luck that at that time, private schools gave more scholarships and my parents thought education was so important.
It wasn't just the qualifications I got, it was the fact I got to mix with people from more fortunate backgrounds and see different lifestyles and different attitudes to life. I was given a different perspective and different aspirations and my cousins never had those opportunities.
I'm close to a lot of my cousins, they are lovely people but we are very different. It really annoys me when they ask me to help them write 'official letters' or speak to 'authority figures' for them because I 'talk well and know all the right words'. It enrages me to be honest because knowing how to do these things and present yourself well should be something that EVERYONE should be able to do and not just because I was lucky enough (with my parents hard work and good attitudes towards education) to have had a fab education.
I posted earlier in this thread about service users on my caseload who are in their 30s who have never worked and are barely literate. One of them once asked "why didn't I grow up 'good' like you?" .Which is a heartbreaking question in itself. I said we just had different opportunities and went to different schools and he said "nah, you can't blame it on that neverthebride, I never really bothered to go to school". There's a big reason right there!.
A great and well rounded education should be available to ALL and we shouldn't just accept that young people can leave school without the very basic skills in literacy and numeracy (without specific sn) and every child SHOULD have someone that cares whether they go to school or not.