Monday night we were eating dinner at the park and a very friendly and over-solicitous ten-year-old struck up a friendship with the twins, exclaiming over them, asking about their number of teeth and other essential details.
Finally she asked, "How do you tell them apart with their clothes off?"
"Well . . . um . . ." I said, "One's a boy and one's a girl."
"I can hardly tell them apart with their clothes on," she said.
"One has a wider face, too," I said. "But I did mix them up when they were first born."
She seemed satisfied with that.