"Tyler…"
It was the way she said it that Eric would remember: not as a warning, not as a scold, but softly, almost pleading, the way you might say the name of someone standing too close to the edge of a roof.
Eric did not look at his son. His eyes stayed on his wife, on her green eyes that would not meet his, on her fingers crushing the plastic cup, on the thin bright line of the string lights swaying above her head.
"What doesn't match?"
* * *
The kit had been sitting on Tyler's desk for three weeks before he used it.
It had started in Ms. Okafor's fourth-period biology class at Mountain View High, in the unit on heredity, which Tyler had expected to be boring and was not. Ms. Okafor was a tall woman with reading glasses on a beaded chain who had a way of making the dullest material sound like gossip. She had drawn Punnett squares on the whiteboard and explained dominant and recessive alleles with the air of someone revealing a family scandal. She talked about eye color, about how it was more complicated than the textbook pretended, about how two blue-eyed parents almost never had a brown-eyed child, although "almost never" was not the same as "never," because biology loved its exceptions. She talked about blood types and earlobes and the ability to taste certain bitter compounds. Then she announced an optional extra-credit project: trace a single inherited trait through your family, or, if your family was willing and could afford it, use a consumer DNA test and write a reflection on what it could and could not tell you.
"Nothing is going to tell you who you are," she had said, tapping the board with the cap of her marker. "But some of these things can tell you where some of your pieces came from. Write about the difference."