In particular, their friends Aaron and Scott from the School of Music had a charming Chinese baby, Mya, who struck Rebecca as a virtual advertisement for adopting Chinese baby girls. The last time they had come for dinner on Willow Street, Rebecca had brought out a Scrabble set to give Mya something to do when she became restless at the table. Not quite two, Mya had set herself a series of tasks, first sorting the letter tiles into matching piles at the four corners of the rug, then arranging the wooden racks into perfect geometric rows, to which she added playing cards sorted by suit, and backgammon pieces, organized in alternating colors, interspersed between the nonsense words she next spelled out with deft precision, using all the Scrabble tiles.

“What’s the plan, sweetie?” George asked Mya respectfully, stepping carefully over her little form on his way back from the kitchen, where he had gone to get the second bottle of wine. She had taken some of her stacked letter tiles and was now repositioning them purposefully on the coffee table to spell out more meaningless words. “Are you practicing to be the next Jenny Holzer?”

“She’s going to grow up to be a taxonomist,” Aaron said proudly.

For every wonderfully healthy baby in her life, Rebecca knew fifty babies with neurodegenerative diseases about which absolutely nothing could be done. Every pregnant woman who had ever sat in her office was carrying a baby with something horribly wrong—spinocerebellar ataxis, trisomy 18, Rett syndrome. Nature usually got it right, Rebecca knew, but those fetuses didn’t come her way.

On their second real date that spring night twenty years ago, when they first ventured out unsupervised by the old ladies, they had meant to go to a movie, but instead they spent the entire evening in a little Greek restaurant on MacDougal Street. George had revealed his Huntington’s background to Rebecca as he had never revealed it to anyone else in his adult life, and this unexpected and rare show of confidence, in its way a herald of their growing attraction, had been rewarded by a long description from her on the Huntington’s study on which, ironically and coincidentally enough, she was working that same summer, conducting clinical interviews for a long-term study of individuals with Huntington’s disease in their family. The disease fascinated Rebecca. So much and so little was known about it. She was avid to discuss it with him, as much as he could tell her. She was completely oblivious to what he was feeling until his eyes suddenly brimmed with tears.

“I’m sorry,” she said, stricken. “I’m an idiot. A complete idiot.”

“No,” he said. “I’m an idiot for trying to pretend it’s not a possibility in my life even though I think about it every day. Every hour, some days. So, do you want me in your study?”

Rebecca’s summer job started right after that, on the first of June. In that week, every single one of her interviews went badly. She didn’t have the right tone. She was too sympathetic, or not sympathetic enough. Too hasty. Too ponderous. Each of her interviewees lived with the possibility of this awful disease and had seen family members sicken and die of it. Many of them walked in the door cheerfully enough, but as the questions progressed, they rapidly revealed themselves to be angry, depressed, sarcastic, bitter, despondent. They needed good friends, and therapy, vacations in the Dordogne—anything but her prying, coldhearted questions for the damned study.