There are 19 different types of smile - but only one natural or "genuine" Duchenne smile.
The theory of this smile is that you can't control or "fake" the muscles that create this type of smile (named after Duchenne the scientist that studied these muscles). Look for raised cheek and crows feet around the eyes. Dimples are not an indicator as that muscle is voluntary.
So the crows feet on your aging face when not smiling indicate past happiness. Forget the Botox.