Galactic chemical evolution of the solar neighborhood, solar twins and exoplanet indicators

Galactic chemical evolution (GCE), solar analogues or twins, and peculiarities of
the solar composition with respect to the twins are inextricably related.
We examine GCE parameters from the literature and present newly derived values
using a quadratic fit that gives zero for a Solar age (i.e. 4.6 Gyr). 
We show how the GCE parameters may be used not only to ``correct'' abundances
to the solar age, but to predict {\bf average} relative elemental 
abundances as a function of age. 
We address the question of whether the solar abundances
are depleted in refractories and enhanced in volatiles and
find that the answer is sensitive to the selection of a
representative standard.  Our best quality data sets do
not support the notion that the Sun is depleted in refractories.  
A simple model allows us to estimate
the amount of refractory-rich material missing from the sun
or alternately added to the average solar twin.  The model
gives between zero and 1.4 earth masses.