“Her mother's file?” Nick repeated.

“Yes.” Dr. Drake appeared to Emme to be slightly confused. “She came here hoping to find out who her donor was, but of course, I could not give her that information. Our donors are guaranteed anonymity unless they choose otherwise, and the name would not have been in the file, so access to it would not have helped her.”

“Wendy was the patient, not Belinda,” he said, as the truth became apparent.

“Yes. She bought several vials of sperm from us twenty or so years ago, as I recall.” She stared at Nick. “You were not aware of this?”

“I never knew how my sister conceived Belinda. I assumed it was a relationship that hadn't worked out.”

“I'm sorry. I assumed you knew.” Dr. Drake appeared flustered.

Emme's attention was drawn to a small booklet on the corner of the desk. FAQ: What if my child asks if he/she has siblings?

“Donor siblings,” she murmured, recalling the magazine in the reception area.

She touched Nick's arm.

“D.S.,” she said softly. “Donor siblings.”

Dr. Drake nodded. “Belinda said she was the spokesperson for her siblings. They were trying to track down their father and were curious about any-”

“Wait a minute.” Nick leaned forward. “What are donor siblings?”

“Children who were conceived using sperm from the same donor,” Dr. Drake explained.

“How many of these… donor siblings did she have?”

“I can't really say.”

“Is that privileged information?” he asked.

“I can't say because I don't know for certain. I know how many live births attributed to that particular donor were reported back to us, but you have to understand, not every woman who successfully conceived and gave birth reported that birth.”

“So you could have had fifty women receive sperm from the same donor, and maybe all fifty of them conceived and had a child, but maybe only thirty of them told you of their success.” Emme thought aloud. “There would be twenty more children out there who were half-siblings to the other thirty. Theoretically.”

Dr. Drake nodded. “Exactly. And keep in mind, some women bought more than one vial of sperm. They may have kept the extras in the freezer until such time as they wanted a second-or third-child.” She stood and began to pace. “It's not unheard of that a woman might give her ‘leftovers’ to a friend. Those children would not be in our network.”

“Is that legal?” Nick asked.

“I don't know of any law against it,” Dr. Drake replied.

“How would Belinda have discovered that she had these donor siblings?”

“The Internet holds a wealth of information, Mr. Perone. It's all in knowing where to look.” Dr. Drake picked up a pen and wrote something on a Post-it note. “Try this website. I think you'll be able to find what you're looking for there.”

She handed the note to Nick. “It's a website where children go to find their half-siblings.”

“Half-siblings?” Nick frowned.

“Certainly. These children may have had different mothers, but they had the same fathers.” Dr. Drake sat back in her chair. “What would you call them?”

“I don't know.”

“If the same man had fathered children by five different wives, what would you call the children?”

“Confused, most likely.”

Dr. Drake smiled weakly.

“Of course they'd be half-siblings,” Nick said.

“Because they had the same father but different mothers,” Dr. Drake pointed out the obvious. “The same applies to these kids. Same father, different mothers. Therefore, half-siblings. Donor siblings.” She tapped the pen on the palm of her hand. “Keep in mind that most of these children will never know who their father is. That one entire half of them is missing. Half of their history is unknown. They know their mother's side of the family, they can see what traits they've inherited from her. But at the same time, there's this great void that may never be filled, this great unknown about that other part of them. By connecting with their half-siblings-other kids just like them, who were conceived with sperm from the same father-perhaps they can fill in some of those blanks.”

“All of their mom's family is tall and blond, but they're short and dark haired,” Emme thought aloud. “They'd want to know where that dark hair came from.”

“Exactly.” Dr. Drake nodded. “They see certain traits that they all share, possibly, and by knowing each other-”

“They'd know a little something about their father. A means to fill in some of the blanks. To understand where they came from, who they are,” Emme said thoughtfully. She understood exactly what questions Belinda and the other donor siblings might have, because her entire life, she'd been asking the same ones. In her case, however, there was no website she could go to, no half-siblings she could locate, to help fill in the blanks of her own story. They simply simmered and bubbled under the surface.

“Right again, Miss Caldwell.”

“So Belinda went on this website, and she asked-” Nick still appeared puzzled. “What would she have asked? How would she know her half-siblings from kids who were conceived from another donor's sperm?”

“You'd have to know the sperm donor's number,” Dr. Drake told him. “In this case, it would be Donor 1735.”

“How would they know the donor's number?” Emme asked.

“The number is no secret. The mothers would have had those. That's the only way the donors are identified. It's a number assigned by the clinic so we know which vial to give the clients. As a matter of fact, it's written right on the vial. The potential mothers choose their prospective donors by the traits they'd like passed on to their children. Dark hair or light, blue eyes or brown, tall or short. Some women want the donor to have a similar ethnic background, some are looking for athletes with high IQs.”

“So you sort of pick through the available data until you find a donor who has what you're looking for,” Emme said. “You want blond hair and blue eyes and a propensity for higher mathematics and when you find a donor on the list who has those traits, you say, I'd like donor number twelve?”

“That's right.” Dr. Drake nodded.

“So with just her donor number, and that Web address, Belinda could locate these other kids.” Nick pondered the possibilities.

“She could find her donor siblings, yes, Mr. Perone. There are almost twelve thousand donor offspring registered on that one website alone. I've been told that almost five thousand donor siblings have been matched already.”

“Five thousand?” Nick frowned. “How many of these donor kids are there?”

“The estimate is between thirty and forty thousand born every year. But again, because there are no regulations, no one really knows for certain.”

“And any one of those kids could be related to Belinda?”

Dr. Drake shrugged. “The sky's the limit, Mr. Perone. Donor 1735 was a popular guy. We sold a lot of his sperm.”

“Like how much?”

“Over fifty vials. That was back in the day before we starting limiting the number of reported births to eight from any one donor. But remember, every vial did not result in a birth. Some resulted in multiple births. Some vials were frozen and never used. Some were passed on to friends.”

“I get the picture,” Nick nodded.

“As I said”-Dr. Drake took a few steps toward the door to indicate, Emme assumed, that their time was up-“the sky's the limit.”