The Evening and the Morning and the Night

My understanding of Octavia E. Butler's purpose of writing 'The Evening and the Morning and the Night', was to create a situation where the reader was posed with the questions: how much can our genetic makeup determine what are capabilities are, how we live our life and what we believe our futures will be?  She goes about this by writing the fictional story of Lynn, a young woman who is the daughter of two individuals who had Duryea-Gode disease.  The disease emerged as a side effect of a Hedeonco, a medicine that cured a variety of cancers.  At first the disease showed no symptoms, but as people aged it progressively grew worse with symptoms including self-mutilation and 'drifting' or going off into another world.
Constant throughout the piece, was a theme of being controlled by DGD and that having the knowledge that you would get the disease determined one's future. (Those who started showing symptoms of DGD were sent to institutions- some of which were nicer such as Dilg and others that were reminiscent of mental health institutes prior to humane laws were put in place.)  For instance, the fact that one was put into a hospital the moment they showed any sign of illness (even if it ended up being a false alarm) represented a lack of control in the most physical sense.  Families would sent their loved ones away, in many cases to be physically restrained to prevent self-mutilation.  On a  mental level, there was a feeling of hopelessness described by the people who knew they had the gene for DGD.  The only way in which some were able to display agency was by committing suicide before the disease took over their bodies.  Such actions represent the extreme, though often real emotions that individuals who have deteriorating conditions may grapple with.  Finally, on several occasions, the characters would reference and article they'd read in a scientific journal about the prognosis and symptoms of DGD.  In the context of this story, it struck me as though they took what the medical community published in scientific papers as the final say- they rarely questioned the accuracy of what was being reported.  This seemed to me as another way that they lost control- they just accepted what unknown doctors told them would be their fate.
While it was a bit of a gloomy read, I enjoyed the way that Butler incorporated a theme that remains prevalent today into her fictional world.