In my view this is almost entirely the issue. Yes there are always exceptional cases where a kid from a terrible background turns out to be a genius self-motivated learner, but for the most part, if a kid has both parents in and out of jail, bouncing from foster home to foster home, poor nutrition, always living in "survival" mode, he's not going to do well in school. All the curriculum theory and standardized testing in the world will never help that kid, and really neither will anything else. Irresponsible parenting is really the root of almost all the problems we have with education, and that problem is outside the scope of what educators can solve.