In sociology, at least, we consider the potential functions and unintended consequences of social relationships, and thus we focus not only on the “happiness” but also on the “unhappiness” brought about by family relationships. Research is then often conducted under the question of how that unhappiness can be alleviated through public support. With the same awareness of the issue, I have been researching “how to reduce the disadvantages (such as a relatively low sense of well-being) that children born into socially disadvantaged families suffer in adulthood due to their disadvantages, that is, how to reduce the “parent-child cycle of disadvantage” through public support.
    According to previous research in Japan, the “parent-child linkage of disadvantage” can already be seen at the age of 0 to 2 years. The long-term effects of early childhood education and care (ECEC) at the age of 0 to 2 years on adult life can be analyzed by comparing the outcomes of the “participating group” and the “non-participating group” with the propensity scores of participation and covariates aligned. In this paper, we introduce the first attempt at such an analysis in Japan.