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. Author manuscript; available in PMC: 2015 Jul 6.
Published in final edited form as: Ann Behav Med. 2014 Apr;47(2):198–207. doi: 10.1007/s12160-013-9538-y

Fig. 1.

Fig. 1

Interpreting patterns of overall and within-pair associations for causation and confounding in monozygotic (MZ) and dizygotic (DZ) twins. a In causal association, the magnitude of the phenotypic association within pairs is the same overall and for both MZ and DZ pairs. b With common environment confounding, the magnitude of the phenotypic association within pairs is attenuated but not eliminated in MZ and DZ twins compared to the overall association. c With both genetic and common environment confounding, the magnitude of the phenotypic association is attenuated in MZ pairs compared to DZ pairs