Of American children with the highest test scores in eighth grade, only 29% of those from low-income families ended up going to college, compared with 74% of those from high-income families. Since the better-off can afford to keep their children in higher education and the poor cannot, breaking out of the cycle is hard. The Economist (source)
Some more data are here.
A society that claims to offer equal opportunities to all its citizens, has to offer them all an equal right to education. Differences in education level between individuals that are not caused by merit, effort or talent but by income inequality of the parents for example – as in this quote – result in a wide range of unjust or unfair inequalities (with regard to knowledge, profession, income etc.).
Or, to put it differently, a society which accepts that children from poor families are less well-educated than children from rich families, even if all these children have the same talent and skills, should explicitly state that it accepts injustice, that it is a society based on injustice. And if it doesn’t accept this, it should do something about the unequal right to education, for example by making education cheaper and more accessible.