Composition of the solar twins with respect to HIP 56948 (dashed line) and the Sun (solid line). The open circles show the effect of adding 6 M_⊕ of a mix of Earth-like and meteoritic-like material (Chambers 2010) to the convection zone of the present Sun (Asplund et al. 2009), and the filled circles the effect of adding 3 M_⊕ of rocky material to the convection zone of HIP 56948. Abundances are normalized with respect to ⟨C, O ⟩. Both the Sun and HIP 56948 require  ~2 M_⊕ of Earth-like material, while the Sun requires much larger quantities of chondrite material. Notice the very small (<0.01 dex) element-to-element scatter.