Social inequality with regard to education seems to be mainly the result of two factors: the reduced success of certain socio-economical categories within the education system and distinct educational requirements once the compulsory education period is over. In this article, we shall focus on the inequality stemming from the choices and personal decisions of individuals by highlighting the influence of social origins as a factor capable of inducing an under-investment in education. Thus, we shall examine how an auto-selection process contributes to the iniquity of the education system. This analysis is based on the theoretical framework of human capital investment developed by Gary Becker (1964) and principally underlines the effects of expectations, uncertainty and cost perception in the differences in evaluations of the profitability of education according to social background. It brings to light reflections on the educational policy.