Mathanxiety
"It is sweeping (your generalisations about class behaviour), but sadly the figures do not lie."
What figures? You still have not produced anything at all to indicate that ?the bottom 20%? of parents? or anything close to it have such poor parenting behaviour that it might cause their children to be unable to learn to read. You mentioned 120,000 ?problem families earlier? ? that only represents around 2% of families in the UK. Another report you cited referred to NEETs ? around 7% of the total teenage population.
The reports you have cited are all very slim on hard numbers. Only the All Party report divides the population of children entering school into bands by socioeconomic class, but the figures given there are averages, and do not give the standard deviation from the mean. But even if that standard deviation was quite small, the nature of the figures means that there would have to be substantial overlap between, at the very least, the adjacent groups. Without that information about overlap it is impossible to validly make the kinds of generalisations you have done from that particular table.
Not only that, but it is an axiom of science that ?correlation cannot imply causation?. Studies normally attempt to exclude confounding factors, in order to at least suggest a degree of causation, but the table in the All Party report does not begin to attempt to do that.
For example, there is another perfectly plausible explanation for higher levels of reading failure among less socially advantaged groups. We know that dyslexic tendencies are hereditary to a significant degree. Since success in our society is highly dependent on being able to read and write, you would expect to find dyslexic individuals consistently being pushed down (or failing to rise up) the socioeconomic ladder, resulting in a clustering of such individuals at the bottom end of the scale. These individuals would then disproportionately pass on their dyslexic tendencies to their offspring.
It really just isn?t valid to make such sweeping assumptions about causation, purely on the basis of what you believe to be ?ironclad correlations?, and any social scientist would tell you as much.