The sound of a baby crying echoed throughout the Drake family home. Ellyn and Edward were fussing more than usual. Sonia tried to rock Ellyn while pacing back and forth in the living room, while the babysitter struggled to calm Edward, who was crying even louder.

"Gosh, what's wrong with them, crying like this together?" Sonia complained, trying to pat Ellyn's back.

“They’re usually not this chaotic,” the babysitter said anxiously. “They’re full, and their diapers are clean. But they’re still fussy.”

Nathan had just come down from the second floor and heard the commotion. He immediately approached.

“I’ll take Edward,” Nathan said, lifting the baby boy from the babysitter’s...