Much remains unknown about the mechanisms underlying this pattern of convergence, as it is possible that there are different causal pathways for the short- and long-term effects. One possible pathway through which ECE programs may have long-term impacts is through changes in children's behavior, particularly in their approaches to learning such as increased self-regulation and attention skills, that they carry through life. Another potential mechanism through which ECE programs may have long-term impacts is through changes in parenting quality or practices. For example, secondary analysis of data from the HSIS revealed persistent impacts on parents' involvement with children's schooling several years later. Additionally, Head Start, as well as the small model ECE programs, place programmatic emphasis on increased parental education and involvement. Because socioeconomic differences in the home environment, parenting, and parents' involvement in education account for a substantial portion of the income achievement gap, changes in parenting could help narrow this gap. Moreover, evidence suggests that there may be beneficial spillover effects of Head Start participation on young siblings, which may be the result of changes in parenting. Finally, as mentioned above, the quality of the K-12 schools that ECE participants attend may help sustain earlier gains, although the research on this is mixed.