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. Author manuscript; available in PMC: 2013 Nov 1.
Published in final edited form as: Behav Genet. 2012 Sep 26;42(6):867–874. doi: 10.1007/s10519-012-9567-5

Figure 1. Extended-Twin Family Model for opposite-sex twins and their parents.

Figure 1

Note: T=special twin environment; D=non-additive genetic effects; E=unique environmental effects; C=common environmental effects; A=additive genetic effects; B=male specific genetic effects; Fa=father; Mo=mother; tm=special twin environment-males; dm=non-additive genes-males; em=unique environment and error-males; sm=special sibling environment-males; am=additive genetic effects-males; bm=male-specific genetic effects; i=assortative mating; tf=special twin environment-females; df=non-additive genes-females; ef=unique environment and error-females; sf=special sibling environment-females; af=additive genetic effects-females;T1=twin 1; T2=Twin2; rd=correlation between non-additive genetic effects in males and females; rt=correlation between special twin environment in males and females; rs=correlation between common environmental factors in males and females.