LAUSR

Recent studies have found that adoptive parents invest in their children equally or more than biological parents do. Most of these studies observed relationships across families, comparing families with adopted children to those without. In this study, alternatively, we focused on within-family comparisons to more fully isolate the relationship between biological ties and parental investments. Using American Time Use Survey (2007–2018; n = 1,152 children) and American Community Survey (2014–2018; n = 34,673 children) data, we employed within-family fixed effects regression models and focused on both parental time and financial investments, using private school enrollment as a proxy for the latter. Our findings show that parents spent less one-on-one, quality, and total time daily with adopted children compared to biological children. In terms of financial investments, 90% of children in the sample received equal investments, meaning that either all or no siblings within the same family were enrolled in private school. However, among families with enrollment differences between siblings, adopted children were significantly less likely than their non-adopted siblings to be enrolled in private school. These findings show that adopted children within mixed-adoption families may receive equal or fewer investments than their non-adopted siblings. The findings highlight the possibility of selection as an interpretation of the adoptive-child advantage, illustrate the importance of within-family studies on this topic, and point to the complexity of parental investments in adopted children.