Focusing on the demographic variables, offspring sex was unrelated to exposure risk or adoption status. Ethnicity was associated with adoption status only; Caucasian participants constituted 94% of the non-adopted sample and but 21% of the adopted sample (X2=134.90, p <.001). Assessment age was related only to exposure risk with older adolescents more likely to be exposed to parent smoking (15.1 yrs. vs. 14.6 yrs., F=13.43, p<.001). Family SES was also related to exposure risk (F=28.41, p < .001) as well as to adoption status (F=60.55, p < .001), but not their interaction. The mean family SES for both exposed and non-adopted adolescents was significantly lower when compared to unexposed and adopted adolescents, respectively. Thus, all adolescent outcome variables included in our analyses were statistically adjusted for age, ethnicity, and family SES.
