At the end of Gattaca, the dialog is pretty clear that Dr. Lamar, who does all the urine-based genetic verification, has a son who admires Vincent's persona as Jerome and that clearly is the reason he does nothing to stop Vincent; indeed, he urges him to board his flight: a dream come true for all of them.
However, when Vincent first adopts Jerome's identity and "interviews" (a standard genetic test) with Gattaca Corporation, it is with Dr. Lamar who probably is not aware of the deception. But in their seemingly daily interaction of "Jerome" peeing a sample for the doctor, at some point the doctor becomes aware that Jerome is a fraud, but never says a thing. It isn't until the surprise genetic test seconds before boarding the rocket that the doctor says "For future reference, right-handed men don't hold it with their left."
It seems implicit that those enforcing genetic purity would view Vincent as a criminal. But certainly Irene (Uma Thurman) abandons such thinking by the end of the story. Why does the Doctor?
Perhaps this hints that many (maybe everyone) in this genome-driven world are sick of the science-enhanced discrimination? Especially those apparently in charge of enforcement. If so, then who is really fostering and promoting the discrimination?