Would you pay to have the ‘best baby’? Liberal eugenics and the troubling quest for human perfection

For a very long time, I dreamed of being cured. I was born in 1981. I learned to walk early enough, but I stumbled and fell more easily than other children. My parents began to worry that something was wrong, that my muscles were weaker than they should be. Eventually, at the age of three, I was diagnosed with a form of spinal muscular atrophy (SMA). In the 1980s, the precise mechanics were not yet understood, but the condition was known to be hereditary, probably linked to a recessive gene. It was also known to be progressive. As I aged, my muscles would not keep pace. At eight, I began to use a wheelchair for longer distances. By the time I was 18, I rarely walked outdoors any more.

It is hard to be young and to know that you are growing weaker rather than stronger. I had all the same aspirations that my nondisabled friends did, but I lived in fear of the future in a way they did not. I spent a lot of time thinking about what...