The TOSS sample was comprised of 909 White (100%) pairs of twin parents, their spouse/partner, and their adolescent child (Neiderhiser & Lichtenstein, 2008) obtained through the use of the Swedish Twin Registry. This study was desgined subsequent to NEAD and used comparable measures of parenting and child behavior. Zygosity was established using DNA and the same validated questionnaire as used in NEAD (Nichols & Bilbro, 1966). The analysis sample was 854 families for whom zygosity information was available (384 MZ parent pairs, 470 DZ parent pairs). Adolescents ranged in age from 11 to 22 years (M = 15.7 years, SD = 2.5 years). Adolescent cousin pairs were the same sex and within 4 years of age of each other (M = 1.8 years; SD = 1.5 years).
