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. 2020 Mar 23;15(3):e0230626. doi: 10.1371/journal.pone.0230626

Fig 1. Nuclear twin family design model.

Fig 1

G, genetic factors; E, environmental factors; dotted lines, genetic paths; a, additive genetic effects; i, non-additive genetic effects; m, environmental transmission from mother to offspring; f, environmental transmission from father to offspring; cs, environmental effects shared by siblings; ct, environmental influences shared by twins; e, unique environmental influences (including measurement error); μ, parent’s phenotypic similarity.