I am curious how segregation is criticized among science fiction novelists. Nowadays there are already stigmas and limits in regard to race and culture. Could the inclusion of genetic improvements aggravate the gaps between social groups?
The bio-punk novel Crache, the sequel to Clade, is a novel about the very topic of the segregation of humanity by genetic manipulation. The workers of this future are relegated to ghettos separated by the manipulation of their genome. If they tried to move or even visit areas where they lacked the proper genetic signatures to access the environment, they could die as a result.
People are hardwired to the environment using genetic modifications and biologically specific drugs used to control the minds and behaviors of the general populace. Migrant workers or braceros are hired temporarily and given a genetic marker which allows them to live in the genetic environment they are working in for the time they are employed.
You might also find Frank Herbert's "Eyes of Heisenberg" relevant. Overview on wikipedia http://en.wikipedia.org/wiki/The_Eyes_of_Heisenberg