Skip to main content
. Author manuscript; available in PMC: 2015 Sep 1.
Published in final edited form as: Dev Psychobiol. 2014 Feb 13;56(6):1278–1289. doi: 10.1002/dev.21207

Figure 1.

Figure 1

Quantitative Genetic Model of Testosterone in Adolescent Male and Female Twins

Note. A = Additive Genetic; C = Shared Environmental; E = Non-Shared Environmental. A, C, and E factors are standardized (M = 0, SD = 1). m = male; f = female. Model for opposite-sex DZ pairs is shown; rA was freely estimated in the qualitative sex-differences model, and fixed to equal 0.5 for all other models. For MZ pairs and same-sex DZ pairs (not shown), rA was fixed to equal 1.0 and 0.5, respectively. The main effect of sex and the linear and quadratic effects of age in years were controlled in all models.