Figure 1From: Genetic and environmental influence on lung function impairment in Swedish twinsBasic path diagram for an opposite sexed twin pair. Am, Cm, Em, Af, Cf, and Ef are the genetic, shared and non-shared environmental variance components for men and women, respectively. The genetic correlation, ra, is set free to be estimated in the model, while the shared environmental correlation, rc, is set to 1.Back to article page