Ten years ago, our daughter Penny was born. She came into the world with a shock of black hair, piercing blue eyes, and, within hours, a diagnosis of Down syndrome.

We learned the biology quickly: Down syndrome is the popular name for trisomy 21, the presence of three copies of the 21st chromosome instead of the typical two. When she was only a few hours old, the doctors told us she would experience some health problems and cognitive delays. The range of those problems was unpredictable.

“Would you take away the Down syndrome if you could?” I asked myself, and my husband, regularly. At first, the answer seemed obvious. What mother wouldn’t make life easier for her child? What father wouldn’t want his daughter’s life free of obstacles and challenges? Then we started to get to know Penny—her thoughtfulness and humor, her love for books and cheeseburgers, her delight in climbing rocks and holding hands. We started to consider how changing her chromosomal makeup would change her, and as time went on, what had once been an obvious question became more complicated. Eventually, it seemed irrelevant.