„About 50–80 per cent of language gaps observed at end of primary school were explained by gaps settled before formal schooling in all three countries. Conversely, at most 20–50 per cent of school-age gaps were generated during schooling. These findings suggest that the roots of social inequality in school-age achievement must be sought primarily in processes transpiring before school life starts.“
Dr. Giampiero Passaretta u. a., Is Social Inequality in School-Age Achievement Generated before or during Schooling? A European Perspective. In: European Sociological Review, 2022, 38, S. 849.