Sample size limitations may have reduced our statistical power to detect differences in the risk for smoking outcomes between Group 2 (HG-HE) and Group 3 (MG-LE) effects. Power to detect differences between these groups was 30%. However, we are able to conclude that high genetic and high environment as compared to low genetic and low environmental risk is associated with offspring ND, and we can conclude that environmental factors contribute to offspring smoking outcomes after accounting for familial vulnerability (i.e. Group 4 vs. 1).
