If you’re trying to examine how institutional and systemic effects can perpetuate inequality, sometimes it’s useful to get away from race and gender and sexual orientation and so on.
So here’s a real-world, class-only example (though it doesn’t take much to tie this to racism or other kinds of bigotry):
Many agree that education is supposed to be the great leveler. Nearly all places fund education by property taxes. So that means that locations where property values are low are going to get fewer quality educational tools and fewer top quality teachers.
(If you’re not going to argue that salary matters, then let’s discuss how CEOs don’t deserve the high economic rents of their salary.)
This means that the “great leveller” DOES NOT LEVEL a damn thing. While there are people who manage to excel despite crappy educational conditions, imagine HOW MUCH BETTER they’d be in a quality school!
So, all other things being equal, if you have a group of people who start in poverty, their kids are going to STAY in poverty because they will have a substandard education compared to those people who begin with wealth. (It’s more complicated than that, but I’m trying to be clear here.)
This would allow people to say “but they could excel in school”, and while that’s technically true, it’s realistically bullshit, even though no one person explicitly acted to make it so.