I’m not sure that I would consider one’s actual education or occupation to be a delimiter of class, but I do think that the attitude towards them plays into it.
My father was the child of a vice president in a middling sized corporation and a law firm office manager. He dropped out of high school and went off to be a hippie. His siblings graduated and went to college, and went into business. He spent most of my childhood stocking grocery shelves to make ends meet, and later worked in asbestos removal.
My mother was the child of a concert violinist who eventually lost that job because of his alcohol problem. She graduated high school, but then also went off to be a hippie. Despite being very poor, most of her siblings ended up with degrees and jobs in computer programming or nursing. Mom cleaned houses until her health couldn’t handle it anymore, then worked as a clerk for awhile.
Despite being quite poor, we lived what I consider to be a solidly middle class lifestyle. Part of that was the unthinking assumption that I would go to college so that I would get a good job, and the cost never entered into it. (Anyone can afford college with enough loans and grants, I’m living proof.)
My older brother decided to follow in my parents’ footsteps and drop out of high school to travel around the country. Twelve years or so later, he is working an apprentice plumber. But his SO is a graduate student, and I would say that they live a middle class lifestyle as well. If they eventually have a child, I have no doubt that they will be expected to go to college and get a good job.
My step-father, on the other hand, comes from what I would consider to be the working poor. His father worked in a shipyard, and Kevin worked there for awhile before ending up collecting money from vending machines. He graduated from high school but never even considered college. His brother is an engineer, but in their family he’s the oddity (a good one) for having a college degree. It was a bonus that he chose to do that, not an expectation.