Parents' education level was coded on a 5-point scale (1 = less than high school, to 5 = professional degree). For parents employed on a full-time basis, occupational status was coded on a 6-point reflected Hollingshead scale (1 = manual laborer, to 6 = professional/managerial). Following procedures outlined in McGue et al. (2007)13, we standardized the educational and occupational status scores for each parent using the mean and standard deviation from the distribution of scores for the non-adoptive families. We then summed these standardized scores for the parents in each family to form a composite socioeconomic (SES) status indicator.
