My mother remembers reading a book in the 80's, and only clearly remembers the cover art. However the date is irrelevant because she doesn't think it was new.
The cover had a face with one brown eye and one green eye.
There is a utopia verging on collapse, wherein all the people look identical. A general olive skin, dark hair, and brown eyes. There are occasionally mutants that are eradicated. The main character of the book had heterochromia and was trying to escape.
I'm sorry that all I have to go on is this, and any help would be very much appreciated