The answer is: The level of education of many parents is low and they are not able to earn as much.
Because of the low level of education, many of the parents unable to obtain high paying careers throughout their life.
This mean that by the time of their pension years, these parents unable to save up enough capital to be passed on to their children, and a lot of them also could not afford to get their children into high level education.
This make the poverty among children seems to be increasing in the past decade.