As They Say -- Spitting Image
How often do you use the term "spitting image" -- as in, Avril Lavigne is a spitting image of Skrillex?
Ask your kids.
Anyway, the phrase refers to people or things that are highly alike, if not identical.
It has two derivatives: spirit and image, which has more to do with a likeness of spirit as well as appearance.
And spit and image -- which literally refers to hocking a loog on something to see your reflection, resulting in a "spitting image".
And speaking of Spitting Image -- this is an interesting tie-in.