Social class and educational attainment of Irish children

It is well known that children from high SES backgrounds do much better in school and this explains, at least proximately, the very sharp SES gradient with regard to university entrance. Or, to put it in English, working class kids get, on average, much worse Leaving Certs and this is why they are much less likely to get to uni' and certainly less likely to get into the more remunerative professional programs. The recent hullaboloo about "Free fees" , on the occasion of my paper on the subject, more or less ignored this inconvenient truth.
But when in the lifecycle does disadvantage set in? Clearly it doesn't just happen at 18. The Growing up in Ireland data allows us to take a snapshot of this gradient when children in Ireland are about 9 years of age.

This graphs the mean maths score by household social class and one can clearly see a pronounced association. Social class is based on the highest class of the two parents - if there are two around. Even at age 8 or 9 coming from a professional/managerial household makes a big difference. Alternatively one could look at the education of the primary carer (usually the mother):

Its still the same old story: if your parents have low education then you are at a considerable disadvantage. Doing some simple multivariate modelling, both factors have an independent effect, as does income and other variables. Girls do worse for example though as is well known the reverse seems to be the case when it comes to doing the Leaving Cert.
To get an idea of the magnitudes involved, the mean and standard deviation of the maths test (which is the Drumcondra test) are respectively-0.64 & 0.92 respectively. When one does the regressions one finds that a child of a graduate mother can expect a score that is about .5 higher than a child of a mother with only minimum education (so about 55% of a std dev). For social class the gradient is flatter: the average difference between the top and bottom social classes is about .26. By comparison, the "penalty" to being a girl is 0.1.
Whether the childrens subsequent education exacerbates or reduces this pattern we cannot say. But Jim Heckman, for example, has argued strongly in favour of dynamic complementarities i.e. that learning begets learning which implies that, if anything, early inequalities get worse over time.
So one lesson from all this is I think, that early intervention is necessary if we are serious about addressing socio-economic inequalities in education. Alls we need to do is get serious about it.