Does she shout for them too? Does she cross her eyes for emphasis like she does at home? Whatever she does, she's never subdued. She may have multiple personalities, but shrinking violet isn't one of them.

"People think I'm histrionic," she says. "Imagine that."

THE BASSLER LAB is abuzz with the news: Danielle Swem is pregnant with twins. The lab assistant (who's the wife of one of the postdocs) told a few people about a half hour ago, and now, to make sure that no one's left out, Bonnie walks into the room where Swem is setting up test tubes and shouts, "Hello! Attention! Danielle and Lee are having twins! Twins!"

Swem accepts the attention calmly; she's probably accustomed to Bassler's turning the spotlight on her. Not much big personal news stays secret in this lab. Everyone knows Mike Federle is interviewing for jobs at Stanford and the University of Chicago, and that Chris Waters's third child will be born in a few days. In fact, pictures of Bassler with the newborn wrapped in his hospital blanket, with the hospital bracelet still on his tiny wrist, surface on the lab's website soon after the birth.

In those photos, Bassler looks as proud as the baby's parents. She may have multiple personalities, but one of them dominates: She's a matriarch. Her students and fellows become her offspring, their families her extended family. She even adopts the reporters who drop in, picking them up at the train station, taking them to her house for dinner, inviting them to play board games. "I've had thirteen babies in my lab," she says proudly.